Elucidation of mechanism involved in adsorption of Pb(II) onto lobeira fruit (Solanum lycocarpum) using Langmuir, Freundlich and Temkin isotherms

Lignocellulosic Byproducts as Bio-Adsorbents for Lead Removal

Water pollution by toxic metals, especially by lead ions, is a serious environmental concern due to these metals' persistence, bioaccumulation, and toxicity. Aiming to reduce metal concentrations to non-toxic levels, this study analyzed the removal of lead from water through adsorption with bio-adsorbents. The adsorbent potential of the following four lignocellulosic byproducts were tested: walnut and chestnut shells, pine wood, and burnt pine wood. Removal rates of 97-99% were achieved at optimized conditions, i.e., at a pH of approximately 7, adsorbent dose of 4 g L-1, and 12 h of reaction. The BET specific surface area was between 1.74 and 4.85 m2 g-1. The pore size of the wood bio-adsorbent was 26.54 nm, and those of the remaining materials were between 5.40 and 7.33 nm. With R2 = 0.998-1.000, the kinetics fit the pseudo-second-order model better, suggesting that chemisorption is the dominant mechanism. Both Langmuir and Freundlich isothermal models fit the data well, with R2 = 0.946-0.999. It can be concluded that all the bio-adsorbents tested have the potential to efficiently remove lead ions from water.

Microwave modified sugar cane bagasse cellulose as an eco-friendly biosorbent for eliminating As(V) from aqueous medium

This work explores the potential of microwave assisted urea modified sugarcane bagasse (UMSCB) as an effective, environment-friendly biosorbent for removing As(V) from an aqueous medium. The synthesized biomaterial was characterized by FTIR analysis that showed the existence of various carboxyl, hydroxyl, and carbonyl functional groups; and SEM analysis of UMSCB showed much higher roughness before the As(V) adsorption of 40.78; indicating that As(V) intricately gets adsorbed onto surface of UMSCB. Batch adsorption experiments demonstrated a removal efficiency of approximately 95 % within 30 min at pH 5. However, UMSCB follows pseudo-second-order kinetics and chemisorption mechanism for removal of As(V). The intra-particle diffusion model indicated that more than one step influences the rate-limiting step. Adsorption equilibrium data shows that the Langmuir model provided the best fit, as determined by correlation coefficient (R2) and chi-square (χ2). Notably, the adsorption capacity (qe) of unmodified sugarcane bagasse (SCB) significantly increased from 4.8 mg/g to 52.8 mg/g upon microwave-assisted urea modification, demonstrating the substantial enhancement in As(V) uptake. Thermodynamic indicators indicated that the biosorption is spontaneous, endothermic, and feasible. The high adsorption efficiency, ease of regeneration, and potential for large-scale application highlight UMSCB as a promising solution for As(V) removal from wastewater.

Novel ACS film for efficient dual adsorption of Cr(VI) and SDS: Mechanistic insights and practical applications

The current study introduces a novel ACS film as a dual-functional adsorbent for the efficient elimination of hexavalent chromium (Cr(VI)) and sodium dodecyl sulphate (SDS) from aqueous systems. Comprehensive batch experiments were directed, and the results were rigorously validated using Response Surface Methodology (RSM). The maximum adsorption capacity was found to be 467.14 and 244.47 mg g-1 for Cr(VI) and SDS, respectively. The adsorption of Cr(VI) followed the Freundlich isotherm model (R2 = 0.985), indicating multilayer adsorption, while SDS adhered to the Langmuir isotherm (R2 = 0.935), suggesting monolayer adsorption. Kinetic studies revealed that Cr(VI) adsorption was best defined by the Pseudo Second Order model (R2 = 0.994), whereas SDS adsorption conformed to the Pseudo First Order model (R2 = 0.975), elucidating distinct adsorption mechanisms. Thermodynamic analyses confirmed that the adsorption processes for both Cr(VI) and SDS were spontaneous and enthalpy-driven. The film performance was evaluated using real effluent samples from textile industries, demonstrating its practical applicability in complex matrices. Additionally, regeneration studies showed sustained adsorption efficiency across five cycles, highlighting the materials reusability and economic viability. This work emphasizes the potential of the ACS film as a versatile and sustainable material for addressing dual pollution challenges, paving the way for scalable applications in environmental remediation.

Decontamination of crystal violet using nanocomposite adsorbent based on pine cone biochar modified with CoFe2O4/Mn-Fe LDH

This study investigates the use of pine cones as a novel and readily available precursor for producing biochar (BC), which is then modified with CoFe2O4 magnetic nanoparticles and Mn-Fe layered double hydroxide (LDH) to enhance its adsorption capacity for removing the cationic dye crystal violet (CV) from aqueous solutions. The physical and chemical properties of the resulting adsorbents-BC (BCPC), BC/CoFe2O4, and BC/CoFe2O4/Mn-Fe LDH-were characterized using FTIR, XRD, VSM, SEM, EDX mapping, and BET analyses. BET results revealed that the specific surface areas of BCPC, BCPC/CoFe2O4, and BCPC/CoFe2O4/Mn-Fe LDH were 43.41, 95.81, and 98.85 m2/g, respectively, indicating a significant enhancement in surface area due to modification. Additionally, the magnetic saturation of the BCPC/CoFe2O4/Mn-Fe LDH composite was 32.35 emu/g, confirming that the composite could be easily separated from the solution using an external magnetic field. The composite achieved a maximum CV dye removal efficiency of 98.54% under optimal conditions: pH = 9, temperature 25 °C, adsorbent dose of 1 g/L, contact time of 70 min, and initial dye concentration of 10 mg/L. Isotherm studies revealed that the Langmuir model provided the best fit for the experimental data, suggesting a monolayer adsorption process on homogeneous surfaces. Kinetic studies indicated that the pseudo-second-order model was the most appropriate, highlighting the importance of chemical interactions in the adsorption process. Thermodynamic analyses revealed that the adsorption process was exothermic and spontaneous, as confirmed by negative enthalpy (∆H°) and Gibbs free energy (∆G°) values. In contrast, the negative entropy (∆S°) indicated a reduction in randomness during adsorption. This study demonstrates that the BCPC/CoFe2O4/Mn-Fe LDH magnetic nanocomposite is an effective, sustainable, and easily separable adsorbent for removing cationic dyes from aqueous environments.

Synthesis of poly (acrylic acid) modified graphene/MoS2 heterostructure-based composite: an effective removal of Pb(II), Cd(II) and Zn(II) from wastewater

Heavy metal contaminants have attracted widespread attention due to their severe toxicity and bioaccumulation. In this study, a novel graphene (EG)/molybdenum disulfide (MoS2) modified with poly (acrylic acid) (PAA) composites (EG/MoS2/PAA) were successfully synthesized via a one-step hydrothermal method and effectively removed Pb(II), Zn(II), and Cd(II) ions from wastewater. The incorporation of PAA within the EG/MoS2 significantly improved sorption ability. The EG/MoS2/PAA composite was characterized using XRD, FTIR, TEM, Raman, SEM-EDS, EIS, and cyclic voltammetry, which confirmed the successful synthesis of the EG/MoS2/PAA composite. The adsorption isotherm and kinetic of Pb(II), Zn(II), and Cd(II) were fitted with the Temkin isotherm and pseudo-second-order model, respectively. The maximum adsorption capacities (qmax) obtained using the Langmuir model were 47.13 mg/g for Pb(II) at pH 5, while 12.59 and 12.89 mg/g for Zn(II) and Cd(II) at pH 7. In the presence of interfering cations (i.e., Na+, Cu2+, Co2+, Fe3+, and Mg2+), the EG/MoS2/PAA adsorbent exhibited high selectivity and excellent reusability after three cycles. The adsorption mechanism of Pb(II), Zn(II), and Cd(II) onto the EG/MoS2/PAA composite surface was found to be primarily controlled by complexation and electrostatic interaction. This novel EG/MoS2/PAA adsorbent has excellent suitability for practical application in the treatment of highly contaminated wastewater.

Improving Triterpenoid Extraction Efficiency from Inonotus hispidus Using Macroporous Adsorption Resin: An Aim for Functional Food Development

The triterpenoids from Inonotus hispidus exhibit several valuable bioactivities, including antioxidant, anti-inflammatory, and anticancer properties, making them highly sought-after for applications in functional foods. To obtain more I. hispidus triterpenoids with higher content for subsequent application in functional food, this study firstly screened a strain with a high triterpenoid yield for the cultivation of fruiting bodies. Afterwards, the static adsorption and desorption capacities of seven macroporous adsorption resins (MARs) for fruiting body triterpenoids were evaluated via static tests, and MAR HPD-600 showed the best performance. The static adsorption kinetics and isotherms of triterpenoids were analyzed further using MAR HPD-600, revealing that the adsorption process followed pseudo-second-order kinetics and the Freundlich model, indicating a spontaneous exothermic reaction. The dynamic adsorption-desorption parameters of MAR HPD-600 were subsequently evaluated to establish the optimal enrichment process. With the optimal strategy, the content of triterpenoids in the desorption solution of MAR HPD-600 increased from 26.72 to 129.28 mg/g, with a high yield of 75.48%. Conclusively, the application of MAR presents an efficient and cost-effective technique for extracting I. hispidus triterpenoids, making it well-suited for functional food production requirements.

Unveiling the adsorption mechanisms and key influencing factors of cyclic acetals on powdered activated carbon

Cyclic acetals (CAs), such as 2-ethyl-5,5-dimethyl-1,3-dioxane (2-EDD) and 2-ethyl-4-methyl-1,3-dioxolane (2-EMD), are emerging odourants in drinking water, raising significant concerns due to their extremely low odour thresholds, high stability, and potential health risks. This study investigated 2-EDD and 2-EMD adsorption performance on six powdered activated carbons (PACs). The adsorption isotherms fitted well with Freundlich (R2 = 0.907∼0.996) and Temkin models (R2 = 0.874-0.997). The adsorption efficiency of 2-EDD (the Freundlich constant KF = 0.0847-0.802) was higher than 2-EMD (KF = 0.0435-0.239), because of its greater molecular mass and higher hydrophobicity. All PACs reached equilibrium in about 120 minutes, and the adsorption kinetics fitted better with the pseudo-second-order model (R2 = 0.920∼0.997), indicating that chemical adsorption significantly contributed to CAs' adsorption. The adsorption rates for 2-EDD (k2 = 0.123-1.235) were lower compared to 2-EMD (k2 = 0.245-4.770). Results from correlation analysis revealed that average pore size, pore volume, and mesoporous fraction were the key PAC properties in controlling CAs' adsorption. Diffusion-chemisorption model, Weber and Morris intraparticle diffusion kinetic model, and Boyd kinetic model were employed to elucidate the adsorption mechanism. The results indicated that the two CAs were interacted mainly through chemical adsorption, with film diffusion serving as the step controlling the rate. PACs exhibited effective performance under neutral to slightly alkaline conditions, as well as in source water and tap water. Meanwhile, 20 mg·L-1 PAC could reduce CAs' concentration from 40 ng·L-1 to 5 ng·L-1. This study provides a benchmark for selecting effective carbon to address odour issues caused by CAs.

Epichlorohydrin/triethylamine modified psyllium as a highly efficient adsorbent for selective adsorption of anionic dyes

To develop new green sustainable adsorbents, herein, psyllium, a polysaccharide, was transformed into a cationic material by introducing a quaternary ammonium group in its structure through a two-step process. Psyllium was epoxidized with epichlorohydrin to epoxy propyl form (EPsy) and the resulting material was reacted with triethylamine to obtain a quaternized psyllium, TPsy. TPsy demonstrates selective elimination of anionic dyes (CR and MO). The maximum % adsorption (Pr) of 93.94 %, and 94.44 % were reported for MO and CR (anionic dyes) respectively within 70 min. The strong adsorption of MO and CR can be attributed to electrostatic attraction and hydrogen bonding. The adsorption process adhered to the pseudo-second-order kinetics indicating chemisorption and Langmuir isotherm suggesting monolayer adsorption, exhibiting a maximum adsorption capacity (qm) of 223.71 mg/g for MO and 260.41 mg/g for CR. TPsy is regenerable even after twelve adsorption-desorption cycles with cumulative q of 903.97 mg/g and 932.83 mg/g for MO and CR respectively. Our study introduces a novel approach by reversing the surface charge of psyllium (anionic, PZC = 2.25) through quaternization to TPsy (cationic, PZC = 6.23), which significantly enhances its efficiency as an anionic dye adsorbent.

Bleaching of Idesia polycarpa Maxim. Oil Using a Metal-Organic Framework-Based Adsorbent: Kinetics and Adsorption Isotherms

Idesia polycarpa Maxim. is a woody oil crop with great potential for edible oil production. While crude oil is rich in pigments, traditional bleaching methods have limited effectiveness in improving its color. In this study, a metal-organic framework (MOF) material, MIL-88B(Fe), was synthesized and used for the bleaching of Idesia polycarpa Maxim. oil. The adsorption selectivity of MIL-88B(Fe) and the adsorption process of carotenoids and chlorophyll were investigated. The results demonstrated that the synthesized MIL-88B(Fe) exhibited excellent bleaching capability, achieving a bleaching rate of 97.67% in 65 min. It showed a strong adsorption effect on pigments, particularly carotenoids. The content of lutein decreased from 118.27 mg/kg to 0.01 mg/kg after 65 min of bleaching. The squalene and phytosterol contents in the oil were minimally affected by the bleaching process, while the free fatty acid content slightly increased due to the high reaction temperature and the adsorbent properties. The adsorption process of MIL-88B(Fe) was best described by a pseudo-first-order kinetic model, indicating that the adsorption was a spontaneous and endothermic chemical process. Moreover, MIL-88B(Fe) demonstrated good safety and reusability, making it a promising novel adsorbent for the bleaching of Idesia polycarpa Maxim. oil and other oils with a high pigment content for the vegetable oil industry.

Magnetic Chitosan Nanocomposites Derived from Industrial Solid Waste: A Promising Approach for Arsenic(III) Remediation

In this paper, the "waste to adsorbent" strategy was proposed to synthesize Fe3O4 nanoparticles using the ultrasonic-assisted coprecipitation method from Bayer industrial waste. The nanoparticles were combined with chitosan (CS) to enhance their physicochemical properties. The well-covered CS on the surface of Fe3O4 is characterized by the nanocomposite's saturation magnetization of 50.2 emu/g, zeta potential of -14.2 mV, and specific surface area of 93.64 m2/g. The highest percentage removal efficiency was 96.73% at pH 4, with the adsorbent dosage of 0.5 g/L and the As(III) concentration of 10 mg/L, which suggests that the material is an ideal adsorbent for arsenic(III) remediation. Furthermore, the effects, kinetics, isotherms, and thermodynamic study of the As(III) adsorption process in an aqueous solution of Fe3O4/CS nanocomposites were thoroughly investigated.

Preparation, characterization, and pesticide adsorption capacity of chitosan-magnetic graphene oxide nanoparticles with toxicological studies

This study investigated magnetic graphene oxide nanoparticles (MGO-NPs) and functionalized with chitosan (CS-MGO-NPs) for removing florasulam, metalaxyl, and thiamethoxam pesticides from water. A comprehensive characterization employing Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), zeta potential measurements, XRD analysis, and surface area/porosity determinations confirmed the successful synthesis of the composites with the desired properties. Factorial experimental design was applied to identify the most significant factors of pesticide concentration, adsorbent amount, temperature, pH, agitation time, and ionic strength on the efficiency of removal of tested pesticides from water samples. CS-MGO-NPs exhibited superior removal efficiencies for all three pesticides compared to MGO-NPs. They achieved high removal rates for florasulam (average 92.94%) and metalaxyl (average 88.95%), while demonstrated moderate effectiveness against thiamethoxam (average 64.04%). Different kinetic and isotherm models described how well the nanoparticles adsorbed each pesticide. According to these models, the pseudo-first-order kinetic model interpreted well the adsorption of florasulam, and thiamethoxam onto CS-GO-NPs. While the pseudo-second-order kinetic model interpreted well the adsorption of metalaxyl. The Freundlich isotherm model gave the best fit with florasulam onto CS-GO-NPs. While the Langmuir isotherm model gave the best fit with metalaxyl and thiamethoxam. Finally, the toxicological studies of CS-MGO-NPs in rats were performed, and it was found negative effects at high doses, suggesting caution is needed for practical applications. Overall, this study shows promise for CS-MGO-NPs in water purification, but safety needs further investigation.

Metal-Organic Frameworks MIL-101(Fe) and MIL-53(Al) as Efficient Adsorbents for Dispersive Micro-Solid-Phase Extraction of Sorafenib in Plasma and Wastewater, Coupled with HPLC-UV Analysis

In the present study, metal-organic frameworks, MIL-101(Fe) and MIL-53(Al), were synthesized under solvothermal conditions and were characterized by Fourier transform infrared spectroscopy, X-ray energy diffraction spectroscopy and scanning electron microscopy. The synthesized metal-organic frameworks were utilized for the purpose of dispersive micro-solid phase extraction of sorafenib in both human plasma and wastewater, which was subsequently followed by high performance liquid chromatography with ultraviolet determination. Parameters affecting extraction efficacy including adsorbent amount, ionic strength, pH, type of elution solvent, adsorption and desorption time were optimized. Under optimal experimental conditions, the linearity in human plasma and wastewater was achieved in the range of 0.25-5.00 and 0.01-0.20 μg/mL, respectively. The extraction recovery for MIL-101(Fe) and MIL-53(Al), respectively, was calculated in human plasma and wastewater and found to be in the range of 86.27-99.47%.

Plasma-assisted MnO surface engineered activated carbon felt for enhanced heavy metal adsorption

This study explores the enhanced adsorption performance of activated carbon felt (ACF) for Cu(II) and Cd(II) ions, achieved using a dual-synergistic approach combining MnO coating and plasma treatment. ACF's intrinsic properties, including a high surface area (~ 1000-2000 m²/g), large porosity, and excellent mechanical stability, make it a promising material for environmental applications. However, its limited surface functional groups hinder its adsorption efficiency for heavy metals. Conventional acid treatments, though effective in introducing functional groups, compromise ACF's structural integrity and pose environmental hazards. The non-thermal plasma method addresses these challenges by introducing oxygen-rich functional groups and MnO species without using harmful chemicals, preserving the material's mechanical and morphological properties. This study addresses key challenges in adsorption technologies, such as inefficiencies in multi-contaminant systems and adsorbent degradation through plasma-aided modifications. The synergistic modification enhances adsorption performance by leveraging mechanisms such as ion exchange, complexation, and co-precipitation. Adsorption experiments revealed maximum adsorption capacities of 163.39 mg/g for Cu(II) and 214.59 mg/g for Cd(II), with an extended equilibrium time of 720 min at pH 5. This research highlights the significance of plasma-aided modification strategies for developing sustainable and efficient heavy metal adsorbents, contributing to advancements in wastewater treatment technologies.

Enhanced sorbent properties by synergistic effect of biomass extract functional groups for effective uranium uptake from aqueous system

Adsorption for uranium removal from aqueous systems has been extensively studied, due to its many advantages. However, the great costs and complexity of many sorbent preparation methods are still restricting the progress. Hence, this research aimed to introduce a novel, simple and green method for enhancing Amberlite IR-120 properties for U(VI) removal. Adsorption process parameters were evaluated by batch method and sorbent was characterized before and after uranium adsorption by FTIR, SEM and EDS analysis. The results demonstrated that sorbent was effective for U(VI) removal at pH 5, 100 mg dose with 60 mg/L of U(VI) concentration within 40 min at higher temperatures. The removal efficiency was 87.7% and process was found feasible according to thermodynamic data. Kinetic modelling showed best correlation with pseudo-second order model (r2 = 0.999) and applied isotherms could all describe investigated process suggesting a complex mechanism of U(VI) uptake. Effect of interfering ions (Pb(II), Ni(II) and Co(II)) in a concentration of 45 and 60 mg/L decreased U(VI) removal to 45%. Additionally, AAS method confirmed that used sorbent has significant affinity towards Pb(II). Desorption study revealed successful uranium recovery in up to 3 cycles of sorption/desorption. The EDS analysis revealed the uranium presence with 4.7% and FTIR analysis revealed bands characteristic for stretching vibrations of O=U=O. Proposed mechanism involved U(VI) uptake via non-covalent interactions, inter/intra-molecular hydrogen bonding and intraparticle diffusion. Techno-economic analysis showed that with used preparation method 1 g of ASP costs 0.022 $. Hence, this study offers a novel method for sorbents properties enhancements.

Tailoring Natural and Fly Ash-Based Zeolites Surfaces for Efficient 2,4-D Herbicide Adsorption: The Role of Hexadecyltrimethylammonium Bromide Modification

Global development has led to the generation of substantial levels of hazardous contaminants, including pesticides, which pose significant environmental risks. Effective elimination of these pollutants is essential, and innovative materials and techniques offer promising solutions. This study examines the modification of natural zeolite (clinoptilolite) and fly ash-based NaA and NaX zeolites with hexadecyltrimethylammonium bromide (CTAB) to create inexpensive adsorbents for removing 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide from water. Detailed characterization of these materials was performed, along with an evaluation of the effects of pH, contact time, temperature, and initial 2,4-D concentration on their sorption capacities. The modified samples exhibited significant changes in elemental composition (e.g., reduced SiO2 and Al2O3 content, presence of Br) and textural properties. The adsorption of the pesticide was found to be an exothermic, spontaneous process of pseudo-second-order kinetics and was consistent with the Langmuir model. The highest sorption capacities were observed for samples modified with 0.05 mol L-1 CTAB, particularly for CliCTAB-0.05.

Selective lead capture using amide-containing COFs: A novel strategy for efficient soil remediation

A critical consideration in the application of phytoremediation to remediate sludge soil contaminated with heavy metals is the potential for leaching risks that prevail prior to the efficient uptake of these metals by plants. The most cost-effective method is to use heavy metal stabilizers with selective adsorption. A novel amide-based COF material (COF-TH) has been synthesized as a heavy metal stabilizer for Pb. COF-TH exhibits significant selectivity for Pb in five-metal-mixed solutions, with a distribution coefficient KD as high as 3279 mL·g-1, which was more than 7.3 times that of other heavy metals. The maximum adsorption capacity of COF-TH for Pb was 189 mg·g-1. The adsorption fitted Langmuir model and intra-particle diffusion model, and satisfied pseudo-second-order kinetic model. The excellent selectivity and adsorption performance originate from the complexation between abundant amide groups and Pb ions. Pot experiments and leaching assays confirm that COF-TH decreased Pb leachate concentrations by 77.8 % without significantly decreasing total phytoextracted amounts of other heavy metals, due to the high selectivity of COF-TH to Pb. Additionally, its positive impact on plant growth and microbial diversity makes it a promising soil remediation agent. This investigation offers a novel approach to mitigate the leaching risk of a specific heavy metal Pb during sludge land application by integrating soil phytoremediation with stabilization techniques.

Biosorption of Cr(VI) by Theobroma cacao pericarp

This paper reports a comprehensive study of Theobroma cacao pericarp (TCP) residues, which has been prepared, characterized, and tested as an inexpensive and efficient biosorbent of Cr(VI) from aqueous solutions. The maximum adsorption capacity of TCP obtained at optimal conditions (pH = 2, dose = 0.5 g L-1, C0 = 100 mg L-1) was qmax = 48.5 mg g-1, which is one of the highest values reported by the literature. Structural and morphological characterization has been performed by FTIR, SEM/EDX, and pHPZC measurements. FTIR analysis revealed the presence of O-H, -NH, -NH2, C = H, C = O, C = C, C-O, and C-C functional groups that would be involved in the Cr(VI) biosorption processes. The experimental equilibrium data of biosorption process were successfully fitted to non-linear Langmuir (R2 = 0.95, χ2 = 11.0), Freundlich (R2 = 0.93, χ2 = 14.8), and Temkin (R2 = 0.93, χ2 = 14.7) isotherm models. Kinetics experimental data were well adjustment to non-linear pseudo-2nd (R2 = 0.99, χ2 = 2.08)- and pseudo-1st-order kinetic models (R2 = 0.98, χ2 = 2.25) and also to intra-particle Weber-Morris (R2 = 0.98) and liquid film diffusion (R2 = 0.99) models. These results indicate that Cr(VI) biosorption on heterogeneous surfaces as well as on monolayers of TCP would be a complex process controlled by chemisorption and physisorption mechanisms. The thermodynamic results indicate that the Cr(VI) biosorption on TCP is a feasible, spontaneous, and endothermic process. TCP can be regenerated with NaOH and reused up to 3 times.

Investigation of the efficacy of Alhagi maurorum plant powder for Janus Green B dye removal from wastewater

The growth of industrial activities, has led to a significant increase in the influx of color pollutants into the environment. Phytoremediation can play a crucial role in enhancing wastewater quality. Accordingly, this study sought to evaluate the effectiveness of Alhagi maurorum plant powder in removing Janus Green B (JGB) dye from aqueous solutions. The adsorbent's properties were characterized through Fourier-transform infrared spectroscopy. The study examined various parameters, including initial dye concentration (20-110 mg/L), adsorbent dosage (0.002-0.02 g), solution pH (2-10), and contact time (5-50 min). The experiments revealed that the maximum dye removal efficiency, 99.51%, was achieved under optimal conditions: pH 7, a contact time of 20 min, an adsorbent dosage of 0.01 g, and an initial dye concentration of 90 mg/L. The adsorption of JGB onto the adsorbent followed the Langmuir isotherm model, with a maximum adsorption capacity of 90.909 mg/g. The kinetic results supported a pseudo-second-order model for the adsorption process, with an R2 value of 0.9999. The calculated Gibbs free energy changes (ΔG°) at temperatures of 288, 298, 308, 318, and 328 K were found to be -5354.28, -5993.61, -6439.66, -7026.51, and -7932.05 kJ/mol, respectively, indicating the spontaneity of the adsorption process.

Silicone-modified black peanut shell (BPS) biochar adsorbents: Preparation and their adsorptions for copper(II) from water

Novel silicone-modified biochar adsorbents (BPS-MBCs) were prepared by utilizing waste black peanut shell (BPS) as a raw biochar and gamma-amino-propyl triethoxysilane (silicone) as an inorganic modifier. The novelty of this work is that the incorporation of silicone into BPS can rise the specific surface area and porosity of BPS-MBCs and elevate their adsorptions for copper (II). Sorption kinetics data for copper (II) were molded using five kinetic equations [i.e. Lagergren 1st-order and 2nd-order, intraparticle diffusion (IN-D), Elovich, and Diffusion-chemisorption]. The equilibrium adsorption data for copper (II) were analyzed using two-parameter isotherm equations [i.e. Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin] and three-parameter Sips, Redlich-Peterson and Toth isotherm models. It was validated that copper (II) sorption on BPS-MBCs matched better with pseudo-2nd-order kinetic, Diffusion-chemisorption and Langmuir isotherm models. The maximal qmLan of BPS-MBC-400 was near 284 mg/g at 45 °C. By multi-phase fitting of IN-D modelling, intra-particle diffusion coefficient (kin-d) and diffusion coefficient of external mass-transfer (DEx-Di) for copper (II) were calculated. The low sorption energy from Temkin and mean free energy from D-R modellings implied that copper (II) sorption was initiated by weak non-covalent bond interactions. Thermodynamic parameters indicated that copper (II) on BPS-MBCs was an endothermic and spontaneous process. Recycling of BPS-MBC-400 for copper (II) suggested it has excellent reusability. The major mechanism of copper (II) on BPS-MBCs is possibly comprised of multiple processes, such as physical adsorption (electrostatic attraction), chemical adsorption (adsorption from functional groups, chelation, and ion exchange) and diffusion-chemisorption. Based on these findings, it is expects that BPS-MBCs are promising sorbents for copper (II) eradication from Cu(II)-including wastewater.

Enhancing Zn (II) recovery efficiency: Bi-divalent nickel-cobalt ferrite spinel NiXCo1-xFe2O4 as a Game-changing Adsorbent-an experimental and computational study

This study presents a comprehensive investigation into NiXCo1-xFe2O4 (x = 0.5) spinel nanoparticles synthesized through a one-pot hydrothermal method using Co(NO3)2.6H2O and Ni(NO3)2.6H2O salts. XRD, FTIR, FESEM, and VSM analyses confirmed a cubic structure of NiXCo1-xFe2O4 (x = 0.5) nanoparticles without impurities. These nanoparticles exhibit efficient Zn (II) adsorption characteristics, following Langmuir isotherm and pseudo-second-order kinetics. The maximum adsorption capacity was measured to be 666.67 mg g-1 at pH = 7, with mechanisms involving both electrostatic attraction and cation exchange. Desorption studies indicate more than 75% Zn (II) recovery in an acidic environment (pH = 2) after three cycles. Computational analysis was used to validate the experimental results through Molecular Dynamics simulations, initially focusing on NiXCo1-xFe2O4 (x = 0.5). Further exploration involved variations in x at 0.25 and 0.75 to identify the optimal Ni and Co ratio in this bivalent cation spinel ferrite. Computational analyses reveal the superior performance of NiXCo1-xFe2O4 (x = 0.75) in Zn (II) removal, supported by radial distribution analysis, VdW energy, Coulombic energy, mean square displacement (MSD), root mean square displacement (RMSD), and interaction energy. This comprehensive study provides valuable insights into the adsorption behavior and structural stability of NiXCo1-xFe2O4 nanoparticles, showcasing potential applications in Zn (II) removal.

Investigation of Eucalyptus camaldulensis and Tamarix aphylla species' capacities for methylene blue removal in wastewater and heavy metal remediation in soil

In the contemporary landscape, the reuse of wastewater holds paramount significance. Concurrently, wastewater carries an array of pollutants encompassing chemical dyes and heavy metals. This study delves into the potential of Tamarix aphylla (TA) and Eucalyptus camaldulensis (EC) species for mitigating heavy metals in soil and eliminating methylene blue dye (MB) from wastewater. The research begins with assessing the dye adsorption process, considering pivotal factors such as initial pH, adsorbent dosage, initial dye concentration, and contact time. Outcomes reveal EC's superiority in dye removal compared to TA. As a bioremediation agent, EC exhibits a 90.46% removal efficacy for MB within 15 min, with pH 7.0 as the operative condition. Equilibrium analysis employs Temkin (T), Freundlich (F), and Langmuir (L) isotherms, revealing an excellent fit with the L isotherm model. The study delves further by probing surface adsorption kinetics through pseudo-first-order (PFO) and pseudo-second-order (PSO) models. Furthermore, to discern the divergent impacts of EC and TA on soil heavy metal reduction, soil samples were collected from three distinct zones: an untouched control area, alongside areas where EC and TA were cultivated at the Yazd wastewater site in Iran. Heavy metal levels in the soil were meticulously assessed through rigorous measurement and statistical scrutiny. The findings spotlight TA-cultivated soil as having the highest levels across all examined factors. Ultimately, EC emerges as the superior contender, proficiently excelling in both MB eliminations from wastewater and heavy metal amelioration in the soil, positioning it as the preferred phytoremediation agent.

Waste-Derived Carbon Nano-Onions for the Removal of Organic Dye from Wastewater and Phytotoxicity Studies

Dyes are extensively employed in industries, namely, textiles, cosmetics, paper, pharmaceuticals, tanning, etc. The effluent released from these industries contains various kinds of harmful dyes that adversely impact living beings and the environment due to their recalcitrant and toxic nature. In this study, an effort has been made to eliminate the methylene blue (MB) from wastewater using carbon nano-onions (CNOs) produced from waste frying oil (WFO) using an economical and eco-friendly wick pyrolysis method. The impact of process variables, namely, pH, temperature, process time, MB dye concentration, and adsorbent, was examined for optimum dye removal. The dye removal efficiency (RE) of 99.78% was obtained in 20 min under optimum conditions. The pseudo-second-order model demonstrated a better kinetic fitting with the experimental data. The Langmuir model represented the maximum adsorption capacity (q max) of 43.11 ± 2.56 mg g-1. The regeneration studies demonstrated that the CNOs achieved ∼99.6% MB dye removal over three cycles. Brassica nigra seeds irrigated in treated wastewater showed better growth (3.29 cm) than untreated dye wastewater, which confirms the environmental sustainability of the overall process.

Lanthanum-doped chitosan-based polyacrylamide double network hydrogels for adsorption of phosphorus from wastewater

Excessive phosphorus in aqueous solutions can cause eutrophication, which can harm aquatic organisms and pose a risk to the safety of drinking water for humans. The Chitosan/Polyacrylamide/Lanthanum (CS/PAM/La) hydrogel was designed to get rid of phosphate from aqueous solutions. La (III) was used to enhance the capacity of adsorption of CS. Polyacrylamide was used to enhance the mechanical properties of CS. The results showed that the adsorption capacity of CS/PAM/La hydrogel for phosphate was increased compared with that of CS. When pH of 5.0, the adsorption capacity was 80.07 mg-P/g. In addition, after five adsorption and desorption cycles, the adsorption efficiency remained above 90%. The mechanism of phosphate adsorption on CS/PAM/La material was analyzed using a mass transfer factor model (MTF) and the possible structure of CS/PAM/La hydrogel was calculated by density functional theory calculation (DFT). The application of CS/PAM/La composite hydrogel for removal of phosphate from actual wastewater was investigated, and the results met the requirement of national standard.

A sustainable and economical solution for CO2 capture with biobased carbon materials derived from palm kernel shells

This study investigates the synthesize of activated carbon for carbon dioxide adsorption using palm kernel shell (PKS), a by-product of oil palm industry. The adsorbent synthesis involved a simple two-step carbonization method. Firstly, PKS was activated with potassium oxide (KOH), followed by functionalization with magnesium oxide (MgO). Surface analysis revealed that KOH activated PKS has resulted in a high specific surface area of 1086 m2/g compared to untreated PKS (435 m2/g). However, impregnation of MgO resulted in the reduction of surface area due to blockage of pores by MgO. Thermogravimetric analysis (TGA) demonstrated that PKS-based adsorbents exhibited minimal weight loss of less than 30% up to 500 °C, indicating their suitability for high-temperature applications. CO2 adsorption experiments revealed that PKS-AC-MgO has achieved a higher adsorption capacity of 155.35 mg/g compared to PKS-AC (149.63 mg/g) at 25 °C and 5 bars. The adsorption behaviour of PKS-AC-MgO was well fitted by both the Sips and Langmuir isotherms, suggesting a combination of both heterogeneous and homogeneous adsorption and indicating a chemical reaction between MgO and CO2. Thermodynamic analysis indicated a spontaneous and thermodynamically favourable process for CO2 capture by PKS-AC-MgO, with negative change in enthalpy (- 0.21 kJ/mol), positive change in entropy (2.44 kJ/mol), and negative change in Gibbs free energy (- 729.61 J/mol, - 790.79 J/mol, and - 851.98 J/mol) across tested temperature. Economic assessment revealed that the cost of PKS-AC-MgO is 21% lower than the current market price of commercial activated carbon, indicating its potential for industrial application. Environmental assessment shows a significant reduction in greenhouse gas emissions (381.9 tCO2) through the utilization of PKS-AC-MgO, underscoring its environmental benefits. In summary, the use of activated carbon produced from PKS and functionalised with MgO shows great potential for absorbing CO2. This aligns with the ideas of a circular economy and sustainable development.

Detection and mapping of the seasonal distribution of water hyacinth (Eichhornia crassipes) and valorization as a biosorbent of Pb(II) in water

In the present research, the presence of water hyacinth (Eichhornia crassipes) on the surface of the San Jose Dam located in the city of San Luis Potosi, S.L.P, Mexico, was monitored and mapped. The monitoring was conducted for 2 years (2018-2020) with remote sensing data from OLI Landsat 8 sensors, based on the normalized difference vegetation index (NDVI). The results demonstrated the capability and accuracy of this method, where it was observed that the aboveground cover area, proliferation, and distribution of water hyacinth are influenced by climatic and anthropogenic factors during the four seasons of the year. As part of a sustainable environmental control of this invasive species, the use of water hyacinth (WH) root (RO), stem (ST), and leaf (LE) components as adsorbent material for Pb(II) present in aqueous solution was proposed. The maximum adsorption capacity was observed at pH 5 and 25 °C and was 107.3, 136.8, and 120.8 mg g-1 for RO, ST, and LE, respectively. The physicochemical characterization of WH consisted of scanning electron microscopy (SEM), N2 physisorption, infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), charge distribution, and zero charge point (pHPZC). Due to the chemical nature of WH, several Pb(II) adsorption mechanisms were proposed such as electrostatic attractions, ion exchange, microprecipitation, and π-cation.

Effective removal of acetamiprid and eosin Y by adsorption on pristine and modified MIL-101(Fe)

In this work, the efficacy of two metal-organic frameworks (MIL-101(Fe) and NH2-MIL-101(Fe)) in eliminating acetamiprid (ATP) insecticide and eosin Y (EY) dye from aqueous solution is tested. An analysis was conducted on the developed nanocomposite's optical, morphological, and structural characteristics. The adsorption isotherm, kinetics, thermodynamics, reusability, and mechanisms for ATP and EY dye removal were assessed. NH2-MIL-101(Fe) adsorbed 76% and 90% of ATP pesticide and EY dye, respectively after 10 to 15 min in optimum conditions. For both adsorbents, with regard to explaining the isotherm data, the Langmuir model offered the most accurate description. Moreover, the adsorption of ATP and EY dye is described by the pseudo-second-order kinetic model. The maximum adsorption capacities of ATP and EY dye on MIL-101(Fe) were 57.6 and 48.9 mg/g compared to 70.5 and 97.8 mg/g using NH2-MIL-101(Fe). The greatest amount of ATP and EY dye clearance was obtained at a neutral medium for both adsorbents. The results of this investigation demonstrate the effectiveness of MIL-101(Fe) and NH2-MIL-101(Fe) as effective substances in the adsorption process for removing pesticides and dyes from aqueous solution.

Potassium adsorption capacity and desorption kinetics in soils of Qenberenaweti sub-watershed, central highlands of Ethiopia

Determining the supply and uptake of K nutrient and the dynamic equilibrium (adsorption-desorption) reactions among the K forms in the soils are not commonly addressed in the highlands of Ethiopia. A study was therefore initiated to determine the adsorption capacity of the exchangeable K and the release kinetics of the non-exchangeable K in the soils of the Qenberenaweti Sub-watershed. Twelve disturbed surface (0-20 cm) soil sub-samples were collected from every farmland which was representative of each pre-identified soil type (Vertic Cambisols, Pellic Vertisols, Pisoplinthic Luvisols, Relictistagnic Cambisols, Pisoplinthic Cambisols, and Plinthofractic Cambisols). A composite sample was made in duplicate for the determination of K adsorption capacity and desorption kinetics per soil type. The mean maximum (69.47 ± 4.31 %) and minimum (56.16 ± 6.04 %) K adsorption rates were obtained from the Plinthofractic Cambisols and Vertic Cambisols, respectively. Among the tested isotherm models, the goodness of the Freundlich was better fit the data of all experimental soils; hence, a modified equation of this model (qe = aCeb/a) could be used to describe the theoretical doses of K fertilizers required to develop K levels in soil solutions. The highest constant K releases from the Plinthofractic Cambisols (47 mg kg-1), Pisiopllintic Cambisols (46 mg kg-1), and Pisoplinthic Luvisols (44 mg kg-1) were attained at the 9th extraction. In comparison, it was noticed at the 7th and 11th extractions of the Relictistagnic Cambisols (45 mg kg-1) and both Pellic Vertisols (48 mg kg-1) and Vertic Cambisols (42 mg kg-1), respectively. The equation of power function was the best to successfully describe the released K+ from all the experimental soils. Eventually, determining the adsorption capacity and release kinetics of K at a site-specific level helps to know the relative potential of the soils to supply K and also plan for an effective K fertilization strategy.

One-step synthesis of a core-shell structured biochar using algae (Chlorella) powder and ferric sulfate for immobilizing Hg(II)

Mercury (Hg) pollution poses a significant environmental challenge. One promising method for its removal is the sorption of mercuric ions using biochar. FeS-doped biochar (FBC) exhibits effective mercury adsorption, however may release excess iron into the surrounding water. To address this issue, a novel magnetic pyrrhotite/magnetite-doped biochar with a core-shell structure was synthesized for the adsorption of 2-valent mercury (Hg(II)). The proposed synthesis process involved the use of algae powder and ferric sulfate in a one-step method. By varying the ratio of ferric sulfate and alga powder (within the range of 0.18 - 2.5) had a notable impact on the composition of FBC. As the ferric sulfate content increased, the FBC exhibited a higher concentration of oxygen-containing groups. To assess the adsorption capacity, Langmuir and Freundlich adsorption models were applied to the experimental data. The most effective adsorption was achieved with FBC-4, reaching a maximum capacity (Qm) of 95.51 mg/g. In particular, at low Hg(II) concentrations, FBC-5 demonstrated the ability to reduce Hg(II) concentrations to less than 0.05 mg/L within 30 min. Additionally, the stability of FBC was confirmed within the pH range of 3.8 - 7.2. The study also introduced a model to analyze the adsorption preference for different Hg(II) species. Calomel was identified in the mercury saturated FBC, whereas the core-shell structure exhibited excellent conductivity, which most likely contributed to the minimal release of iron. In summary, this research presents a novel and promising method for synthesizing core-shell structured biochar and provides a novel approach to explore the adsorption contribution of different metal species.

Isotherm and kinetic studies on adsorption of gasoline and kerosene using jujube and barberry tree stem powder and commercially available activated carbon

Herein, the application of granular activated carbon, jujube, and barberry tree stem powder for the removal of gasoline and kerosene from water was investigated. Kerosene removal rates upwards of 68.48, 83.87, and 99.02% were achieved using jujube tree stem powder, barberry tree stem powder, and granular activated carbon, respectively. Besides, gasoline removal rates upwards of 69.35, 55.02, and 95.59% were attained using jujube tree stem powder, barberry tree stem powder, and granular activated carbon, respectively. Isotherm data were further investigated and fitted using Langmuir, Freundlich, and Elovich models. The results indicated that the adsorption onto jujube adsorbent is a multilayer adsorption process over a heterogeneous surface, which is best illustrated by the Temkin (Ave. R2= 0.95) model. It was found that the Temkin isotherm (Ave. R2= 0.81) best describes the properties of barberry stem powder in the adsorption of gasoline and kerosene from water. Moreover, the best models to describe the characteristics of granular activated carbon in the adsorption of gasoline and kerosene from water were Freundlich (Ave. R2= 0.74) and Langmuir (Ave. R2= 0.73) isotherms, respectively. The adsorption kinetics showed that the pseudo-second-order was appropriate in modeling the adsorption kinetics of gasoline and kerosene to the studied adsorbents (R2>0.74).

Unlocking the potential of biochar: an iron-phosphorus-based composite modified adsorbent for adsorption of Pb(II) and Cd(II) in aqueous environments and response surface optimization of adsorption conditions

In this work, iron-phosphorus based composite biochar (FPBC) was prepared by modification with potassium phosphate and iron oxides for the removal of heavy metal ions from single and mixed heavy metal (Pb and Cd) solutions. FTIR and XPS characterization experiments showed that the novel modified biochar had a greater number of surface functional groups compared to the pristine biochar. The maximum adsorption capacities of FPBC for Pb(II) and Cd(II) were 211.66 mg·g-1 and 94.08 mg·g-1 at 293 K. The adsorption of Pb(II) and Cd(II) by FPBC followed the proposed two-step adsorption kinetic model and the Freundlich isothermal adsorption model, suggesting that the mechanism of adsorption of Pb(II) and Cd(II) by FPBC involved chemical adsorption of multiple layers. Mechanistic studies showed that the introduction of -PO4 and -PO3 chemisorbed with Pb(II) and Cd(II), and the introduction of -Fe-O increased the ion exchange with Pb(II) and Cd(II) during the adsorption process and produced precipitates such as Pb3Fe(PO4)3 and Cd5Fe2(P2O7)4. Additionally, the abundant -OH and -COOH groups also participated in the removal of Pb(II) and Cd(II). In addition, FPBC demonstrated strong selective adsorption of Pb(II) in mixed heavy metal solutions. The Response Surface Methodology(RSM) analysis determined the optimal adsorption conditions for FPBC as pH 5.31, temperature 26.01 °C, and Pb(II) concentration 306.30 mg·L-1 for Pb(II). Similarly, the optimal adsorption conditions for Cd(II) were found to be pH 5.66, temperature 39.34 °C, and Cd(II) concentration 267.68 mg·L-1. Therefore, FPBC has the potential for application as a composite-modified adsorbent for the adsorption of multiple heavy metal ions.

Adsorption-desorption of 241Am(Ⅲ) on montmorillonite colloids and quartz sand: Effects of pH, ionic strength, colloid concentration and grain size

Clay colloids in the subsurface environment have a strong adsorption capacity for radionuclides, and the mobile colloids will carry the nuclides for migration, which would promote the movability of radionuclides in the groundwater environment and pose a threat to the ecosphere. The investigations of the adsorption/desorption behaviors of radionuclides in colloids and porous media are significant for the evaluation of the geological disposal of radioactive wastes. To illustrate the adsorption/desorption behaviors of 241Am(Ⅲ) in Na-montmorillonite colloid and/or quartz sand systems at different pH (5, 7 and 9), ionic strengths (0, 0.1 and 5 mM), colloid concentrations (300 and 900 mg/L), nuclide concentrations (500, 800, 1100 and 1400 Bq/mL) and grain sizes (40 and 60 mesh), a series of batch sorption-desorption experiments were conducted. Combining the analysis of the physical and chemical properties of Na-montmorillonite with the Freundlich model, the influencing mechanism of different controlling factors is discussed. The experimental results show that the adsorption/desorption behaviors of 241Am(Ⅲ) in Na-montmorillonite colloid and/or quartz sand strongly are influenced by the pH value and ionic strength of a solution, the colloid concentration as well as quartz sand grain size. The adsorption and desorption isotherms within all the experimental conditions could be well-fitted by the Freundlich model and the correlation coefficients (R2) are bigger than 0.9. With the increase in pH, the adsorption partition coefficient (Kd) at 241Am(Ⅲ)-Na-montmorillonite colloid two-phase system and 241Am(Ⅲ)-Na-montmorillonite colloid-quartz sand three-phase system presents a trend which increases firstly followed by decreasing, due to the changes in the morphology of Am with pH. The Kd of 241Am(Ⅲ) adsorption on montmorillonite colloid and quartz sand decreases with increasing in ionic strength, which is mainly attributed to the competitive adsorption, surface complexation and the reduction of surface zeta potential. Additionally, the Kd increases with increasing colloid concentrations because of the increase in adsorption sites. When the mean grain diameter changes from 0.45 to 0.3 mm, the adsorption variation trends of 241Am(Ⅲ) remain basically unchanged. The research results obtained in this work are meaningful and helpful in understanding the migration behaviors of radionuclides in the underground environment.

Adsorption of Ciprofloxacin on Clay Minerals in Argentinian Santa Rosa-Corrientes Soils

The presence of antibiotics in soils is increasing drastically in last decades due to the intensive farming industry and excessive human consumption. Clay minerals are one of the soil components with great adsorption capacity for organic pollutants. The study of interactions between antibiotics and mineral surfaces will give us scientific knowledge of these pollutants through soils. In this work, we study the adsorption of the antibiotic ciprofloxacin in the clay mineral fraction of soils from the Argentinian zone of Santa Rosa (Corrientes), in a collaborative research of experiments and atomistic modelling calculations of the intercalation of ciprofloxacin in the interlayer space of montmorillonite. Adsorption and desorption isotherms were performed and compared with different isotherm models. Additionally, enthalpy, entropy, and free energy were determined from equilibrium constants at a function of temperature. All these experiments and calculations lead to the conclusions that two adsorption types of ciprofloxacin are found on clay minerals: one weakly sorbed that is released during the desorption experiments, and other one strongly joined that remains in the soil.

A two-in-one thiosemicarbazide and whole pine needle-based adsorbent for rapid and efficient adsorption of methylene blue dye and mercuric ions

Herein, we report the synthesis of an oxidized pine needle-thiosemicarbazone Schiff base (OPN-TSC) from whole pine needles (WPN) as a dual-purpose adsorbent to remove a cationic dye, methylene blue (MB), and Hg2+ ions in separate processes. The adsorbent was synthesized by periodate oxidation of WPN followed by a reaction with thiosemicarbazide. The syntheses of OPN and OPN-TSC were confirmed by FTIR, XRD, FESEM, EDS, BET, and surface charge analysis. The emergence of new peaks at 1729 cm-1 (-CHO stretching) and 1639 cm-1 (-COO- stretching) in the FTIR spectrum of OPN confirmed the oxidation of WPN to OPN. FTIR spectrum of OPN-TSC has a peak at 1604 cm-1 (C = N stretching), confirming the functionalization of OPN to OPN-TSC. XRD studies revealed an increase in the crystallinity of OPN and a decrease in the crystallinity of OPN-TSC because of the attachment of thiosemicarbazide to OPN. The values of %removal for MB and Hg2+ ions by OPN-TSC were found to be 87.36% and 98.2% with maximum adsorption capacity of 279.3 mg/g and 196 mg/g for MB and Hg2+ ions, respectively. The adsorption of MB followed pseudo-second-order kinetics with correlation coefficient (R2 of 0.99383) and Freundlich isotherm (R2 = 0.97239), whereas Hg2+ ion removal demonstrated the Elovich (R2 = 0.97076) and Langmuir isotherm (R2 = 0.95110). OPN-TSC is regenerable with significant recyclability up to 10 cycles for both the adsorbates. The studies established OPN-TSC as a low-cost, sustainable, biodegradable, environmentally benign, and promising adsorbent for the removal of hazardous cationic dyes and toxic metal ions from wastewater and industrial effluents, especially the textile effluents.

In Situ Synthesis of NH2-MIL-53-Al/PAN Nanofibers for Removal Co(II) through an Electrospinning Process

In this study, researchers developed a novel composite material called NH2-MIL-53-Al/PAN, which consists of metal-organic frameworks (MOFs) grown on electrospun PAN nanofibers (NFs). The successful formation of the composite was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR), and the hydrophilicity of NH2-MIL-53-Al/PAN was demonstrated by the water contact angle (WCA). Batch experiments were conducted to investigate the adsorption performance of Co(II) under different conditions. The maximum adsorption capacity reached 58.72 mg/g, and almost 95% of the adsorption was achieved within the first 6 h. The adsorption process was found to be spontaneous and endothermic and followed the pseudo-second-order kinetics and Langmuir models. Chemisorption and molecular layer adsorption are the main mechanisms of adsorption, and X-ray photoelectron spectroscopy (XPS) analysis further reveals that the interaction between the adsorbent and cobalt is a coordination interaction. In this study, NH2-MIL-53-Al was grown in situ on PAN to ensure effective loading of MOFs and prevent agglomeration during the NF mixing process. This approach successfully addressed the challenge of exposing active sites within the embedded MOF crystals. Additionally, it overcame the difficulty of recycling traditional MOF adsorbents. As a result, the exceptional performance of MOF NFs offers a promising solution for the efficient removal of cobalt-containing wastewater.

Techno-economic assessment of waste mandarin biochar as a green adsorbent for binary dye wastewater effluents of methylene blue and basic fuchsin: Lab- and large-scale investigations

Treating polluted wastewater effluents on a large-scale requires the development of high performance and cost-effective adsorbents. The recycling of waste mandarin peels, an environmentally friendly, and copiously available waste biomass into biochar (MRBC), has been approached. In the context of finding affordable and effective solutions for depollution of wastewater, MRBC was used for the adsorption of two dyes: methylene blue (MB) as well as basic fuchsin (BF) from their individual solutions and binary combinations. Batch adsorption studies were performed by employing the Box-Behnken (BB) design. The adsorption competency of dyes was analyzed to find the percentage removal (%R) and the adsorption capacity (qe, mg/g). The dependent parameters (qe and %R) were determined as a function of pH, dose of MRBC (AD), contact time (CT), and concentration of methylene blue [MB]/ basic fuchsin [BF]. Removal of 98.14% of MB and 83.18% of BF was successfully achieved. Equilibrium experiments depicted that Langmuir and Freundlich models suit adsorption of dyes. The maximum adsorption capacity (qmax) was 99.11 (MB) and 78.01 mg/g (BF), individually. However, when the dyes are combined, the qmax decreased to 57.09 and 68.52 mg/g for MB and BF, correspondingly. The cost of MRBC was estimated to be ∼ 4 USD/kg, while the overall cost of wastewater treatment was estimated to be 1.06 USD/m3/year.

Comprehensive review on pH and temperature-responsive polymeric adsorbents: Mechanisms, equilibrium, kinetics, and thermodynamics of adsorption processes for heavy metals and organic dyes

Wastewater treatment technologies have been developed to address the health and environmental risks associated with toxic and cancer-causing dyes and heavy metals found in industrial waste. The most commonly used method to mitigate and treat such effluents is adsorption, which is favored for its high efficiency, low costs, and ease of operation. However, traditional adsorbents have limitations in terms of regeneration and selectivity compared to smart adsorbents. Smart polymeric adsorbents, on the other hand, can undergo physical and chemical changes in response to external factors like temperature and pH, enabling a selective adsorption process. These adsorbents can be easily regenerated and reused with minimal generation of secondary pollutants during desorption. The unique properties acquired by stimuli-responsive adsorbents have encouraged researchers to investigate their potential for the selective and efficient removal of organic dyes and heavy metals. This comprehensive review focuses on two common stimuli, pH and temperature, discussing the fabrication methods and characteristics of smart adsorbents responsive to these factors. It also provides an overview of the mechanisms, isotherms, kinetics, and thermodynamics of the adsorption process for each type of stimuli-responsive adsorbent. Finally, the review concludes with discussions on future perspectives and considerations.

Aluminium dross waste utilization for phosphate removal and recovery from aqueous environment: Operational feasibility development

The need to minimize eutrophication in water bodies and the shortage of phosphate rock reserves has stimulated the search for sequestration and recovery of phosphate from alternative sources, including wastewater. In this study, aluminium dross (AD), a smelting industry waste/by-product, was converted to high-value material by encapsulation in calcium alginate (Ca-Alg) beads, viz. Ca-Alg-AD and utilized for adsorptive/uptake removal and phosphate recovery from an aqueous environment. Encapsulation of AD in alginate beads solves serious operational difficulties of using raw AD material directly due to density difference constraining efficient contact of AD with pollutants present in water and post-treatment recovery of AD material. The phosphate removal was evaluated in both batch and continuous flow operation modes. The batch adsorption study revealed 96.86% phosphate removal from 10 mg L-1 of initial phosphate concentration in 70 min of optimal contact time. Further, the phosphate removal potential of Ca-Alg-AD beads turned out to be independent of solution pH, with an average of 95.93 ± 1.40 % phosphate removal in the 2-9 pH range. The result reflects phosphate adsorption on Ca-Alg-AD beads following a second-order pseudo-kinetic model. Ca-Alg-AD beads-based adsorption followed Freundlich and Langmuir isotherm models. Further, a continuous packed bed column study revealed a total phosphate adsorption capacity of 1.089 mg g-1. The chemical composition, physical stability, and surface properties of Ca-Alg-AD beads were analyzed by means of state-of-the-art analytical techniques, such as Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetry/Differential Thermal Analysis (TG/DTA). These characterization techniques comprehend the mechanism and influence of surface properties and morphology on the phosphate adsorption behaviour, which induce the involvement of multiple mechanisms such as ligand complexation, ion exchange, and electrostatic attraction for phosphate adsorption on Ca-Alg-AD beads.

Investigation of ternary Zn-Co-Fe layered double hydroxide as a multifunctional 2D layered adsorbent for moxifloxacin and antifungal disinfection

Layered double hydroxides have recently gained wide interest as promising multifunctional nanomaterials. In this work, a multifunctional ternary Zn-Co-Fe LDH was prepared and characterized using XRD, FTIR, BET, TEM, SEM, and EDX. This LDH showed a typical XRD pattern with a crystallite size of 3.52 nm and a BET surface area of 155.9 m2/g. This LDH was investigated, for the first time, as an adsorbent for moxifloxacin, a common fluoroquinolones antibiotic, showing a maximum removal efficiency and equilibrium time of 217.81 mg/g and 60 min, respectively. Its antifungal activity, for the first time, was investigated against Penicillium notatum, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, and Mucor fungi at various concentrations (1000-1.95 µg/mL). This LDH was found to be effective against a variety of fungal strains, particularly Penicillium and Mucor species and showed zones of inhibition of 19.3 and 21.6 mm for Penicillium and Mucor, respectively, with an inhibition of 85% for Penicillium species and 68.3% for Mucormycosis. The highest antifungal efficacy results were obtained at very low MIC concentrations (33.3 and 62 µg/ml) against Penicillium and Mucor, respectively. The results of this study suggest a promising multifunctional potential of this LDH for water and wastewater treatment and disinfection applications.

Eco-friendly and cost-effective adsorbent derived from blast furnace slag with black liquor waste for hazardous remediation

The current investigation concerns with preparation eco-friendly and cost-effective adsorbent (mesoporous silica nanoparticles (SBL)) based on black liquor (BL) containing lignin derived from sugarcane bagasse and combining it with sodium silicate derived from blast furnace slag (BFS) for thorium adsorption. Thorium ions were adsorbed from an aqueous solution using the synthesized bio-sorbent (SBL), which was then assessed by X-ray diffraction, BET surface area analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX), and Fourier transforms infrared spectroscopy (FTIR). Th(IV) sorption properties, including the pH effect, uptake rate, and sorption isotherms across various temperatures were investigated. The maximum sorption capacity of Th(IV) on SBL is 158.88 mg/L at pH value of 4328 K, and 60 min contact time. We demonstrated that the adsorption processes comport well with pseudo-second-order and Langmuir adsorption models considering the kinetics and equilibrium data. According to thermodynamic inspections results, the Th(IV) adsorption process exhibited endothermic and random behavior suggested by positive ΔH° and ΔS° values, while the negative ΔG° values indicated a spontaneous sorption process. The maximum Th(IV) desorption from the loaded SBL (Th/SBL) was carried out at 0.25 M of NaHCO3 and 60 min of contact. Sorption/desorption processes have five successive cycles. Finally, this study suggests that the recycling of BFS and BL can be exploited for the procurement of a promising Th(IV) adsorbents.

Natural chitosan-based carbon dots as an eco-friendly and effective corrosion inhibitor for mild steel in HCl solution

Polysaccharide chitosan and L-histidine were applied to synthesize chitosan-based carbon dots (CA-CDs) by a simple laser ablation method. After characterization of the CA-CDs by FT-IR, UV-vis, Raman, XRD, TEM, and XPS, the CA-CDs were introduced as an eco-friendly and high-performance corrosion inhibitor for mild steel (MS) in 1.0 M HCl solution. The inhibition action and mechanism of CA-CDs were determined by weight loss and electrochemical measurements, in combination with SEM, AFM, and XPS. The results show that CA-CDs as mixed-type inhibitors could effectively weaken the corrosion of MS in 1.0 M HCl solution, and their maximum inhibition efficiency reaches 97.4 % at 40 mg L-1. The adsorption behavior of CA-CDs well obeys the Langmuir adsorption isotherm containing both chemisorption and physisorption. The chemisorption mainly results from the multiple adsorption sites in the CA-CDs, and the physical adsorption is due to the blocking and barrier effect of CA-CD nanoparticles. Both adsorption behaviors were proposed to elucidate the corrosion inhibition mechanism of CA-CDs.

Adsorption of uranium(VI) by natural vermiculite: Isotherms, kinetic, thermodynamic and mechanism studies

Human activities such as mining uranium resources, hydrometallurgy, and nuclear fuel preparation inevitably produce wastewater sludge containing radionuclides, posing a severe threat to the environment around the production site. Natural clay minerals have been widely used in groundwater pollution remediation because of their high cation exchange capacity. Through static batch experiments, the optimal pH range of vermiculite for U(VI) adsorption was 6-8,the maximum adsorption capacity was 1.62 × 10-5 mol g-1. The kinetic adsorption results indicated that the adsorption mode was mainly multilayer non-homogeneous chemisorption. In addition, the adsorption of vermiculite on U(VI) was found to be a heat absorption process according to the thermodynamic model fitting, and the spontaneous reactivity of U(VI) adsorption on vermiculite surface was positively correlated with temperature and negatively correlated with the initial concentration of U(VI). Combined with SEM-EDS and FT-IR results, the adsorption process of vermiculite on U(VI) is mainly an ion exchange and complexation reaction, and U(VI) is removed in the form of ≡ SUOU22+ or ≡ SOUO2OH, etc., by XPS means. The results of this study not only investigated the adsorption behavior and mechanism of natural vermiculite in groundwater contaminated with simulated uranium but also provided theoretical support for its feasibility in remediating uranium-polluted groundwater.

Combining computational tools and experimental studies towards endocrine disruptors mitigation: A review of biocatalytic and adsorptive processes

The endocrine disruptors (EDCs) are an important group of emerging contaminants, and their mitigation has been a huge challenge due to their chemistry complexity and variety of these compounds. The traditional treatments are inefficient to completely remove EDCs, and adsorptive processes are the major alternative investigated on their removal. Also, the use of EDCs degrading enzymes has been encouraged due to ecofriendly approach of biocatalytic processes. This paper highlights the occurrence, classification, and toxicity of EDCs with special focus in the use of enzyme-based and adsorptive technologies in the elimination of EDCs from ambiental matrices. Numerous prior reviews have focused on the discussions toward these technologies. However, the literature lacks theoretical discussions about important aspects of these methods such as the mechanisms of EDCs adsorption on the adsorbent surface or the interactions between degrading enzymes - EDCs. In this sense, theoretical calculations combined to experimental studies may help in the development of more efficient technologies to EDCs mitigation. In this review, we point out how computational tools such as molecular docking and molecular dynamics have to contribute to the design of new adsorbents and efficient catalytic processes towards endocrine disruptors mitigation.

Adsorption and Dispersion Effect of Sodium Lignosulfonate on Fine SiC Particles in Aqueous Media

This study presented a novel modification method for fine SiC powder by using sodium lignosulfonate as a dispersant. The adsorption behavior of sodium lignosulfonate on the SiC/water interface and its effect on the performance of a fine SiC slurry were systematically investigated. The adsorption results showed that sodium lignosulfonate formed monolayer adsorption on the surface of fine SiC and that the saturated adsorption capacity was 1.3263 mg/g. The adsorption reached equilibrium within 3 h and was mainly controlled by active sites on the SiC surface. The dispersion, stability, and zeta potential of modified SiC powder were improved after sodium lignosulfonate adsorption. The zeta potential of modified SiC reached a minimum value of -44.8 mV at pH 12. Modified SiC suspensions had great stability in a wider pH range of 6-12. Modified SiC slurry with 54 vol % solid loading had a low viscosity of 173 mPa·s at pH 10. Subsequently, coarse SiC powder was added for slip casting. A mixed slurry with high solid loading (69 vol %) and low viscosity (583 mPa·s) was prepared using modified SiC and coarse SiC powders at a mass ratio of 2:3. Finally, recrystallized SiC green body with high density (2.6492 g/cm3) was obtained.

Influence by varying organic matter content and forms in suspended particulate matter: impacts on the adsorption of tetracycline and norfloxacin

Antibiotics are commonly detected in natural waters. The organic matter (OM) in suspended particulate matter (SPM) has a critical impact on the adsorption of antibiotics in water. We investigated the contribution of OM content and form to the adsorption of tetracycline (TC) and norfloxacin (NOR) in the SPM of Taihu Lake. To change the content and form of OM in SPM, the samples were subjected to pyrolysis at 505 ˚C and oxidization with H2O2, respectively. Combustion almost completely removed OM, while oxidation removed most of the OM and transformed the remaining OM. Regardless of whether the OM changed or not, the adsorption of NOR and TC by SPM was more in line with the pseudo-second-order kinetic model instead of pseudo-first-order. The fitting of the intraparticle diffusion model showed that the removal of OM had a certain degree of change in the adsorption process. The isothermal adsorption of TC in all samples was more in line with the Temkin model. The isothermal adsorption of NOR in the oxidized sample conformed to the Temkin model, while it conformed to the Langmuir model in the original sample and the sample removed OM via combustion. The adsorption capacity of SPM with almost complete removal of OM significantly decreased, while conversely, the adsorption capacity of SPM after oxidation increased. This indicates that both the content and form of OM affect the adsorption of antibiotics by SPM, and the form of OM has a greater impact. The contribution of OM to NOR adsorption was greater than that of TC. In conclusion, the results verify the importance of OM in adsorbing antibiotics onto SPM, which may provide basic data for antibiotic migration in surface water.

Synthesis & fabrication of O-linked polymeric hybrids for recovery of textile dyes: Closed loop economy

Dyes are an important resource employed for the production systems in textile, paper, paint and leather industry. An estimate of 200,000 tons of dyes are discharged as textile effluent each year worldwide. It becomes imperative to recover these dyes by treating the effluents using economically viable routes. The present research was undertaken with the objective to attain zero emission and zero waste through development of novel polymeric hybrids as adsorbents. For this purpose, metal moieties (Al3+, Si4+, Ti4+ and Zr4+) were hybridized with polyacrylic acid, and cellulose acetate for the uptake of selected dyes under optimized parameters. The structural elucidation of four synthesized hybrids (MP-Al, MP-Si, MP-Ti and MP-Zr) by FTIR, EDX and TGA confirmed O-linked grafting of metal moieties with polymers and thermally stable porous materials. SEM micrographic images displayed void spaces providing channels for effective adsorption. The batch experiments demonstrated removal of malachite green (77-96%) and congo red (70-82%) upon contact of initial 45 min on polymeric hybrids On the other hand, pristine polyacrylic acid and cellulose acetate showed remarkably low removal of dyes. The adsorption mechanism is proposed as physical in nature following type II isotherm. Further, Langmuir and Ho's pseudo second order fitness was evaluated. In order to determine the economic viability of the present research, the real textile dyes were recovered in three consecutive cycles of adsorption and chemical treatment of hybrids. The results propose a system with positive impact on economy by maximum utilization of hybrids as adsorbents and recovery of textile dyes for reuse in textile processing.

Efficiency of Ppy-PA-pani and Ppy-PA composite adsorbents in Chromium(VI) removal from aqueous solution

In this study, first time the combination of composites with Phytic acid (PA) as the organic binder cross-linker is reported. The novel use of PA with single and double conducting polymers (polypyrrole (Ppy) and polyaniline (Pani)) were tested against removal of Cr(VI) from wastewater. Characterizations (FE-SEM, EDX, FTIR, XRD, XPS) were performed to study the morphology and removal mechanism. The adsorption removal capability of Polypyrrole - Phytic Acid - Polyaniline (Ppy-PA-Pani) was deemed to be higher than Polypyrrole - Phytic Acid (Ppy-PA) due to the mere existence of Polyaniline as the extra polymer. The kinetics followed 2nd order with equilibration at 480 min, but Elovich model confirmed that chemisorption is followed. Langmuir isotherm model exhibited maximum adsorption capacity of 222.7-321.49 mg/g for Ppy-PA-Pani and 207.66-271.96 mg/g for Ppy-PA at 298K-318K with R2 values of 0.9934 and 0.9938 respectively. The adsorbents were reusable for 5 cycles of adsorption-desorption. The thermodynamic parameter, ΔH shows positive values confirmed the adsorption process was endothermic. From overall results, the removal mechanism is believed to be chemisorption through Cr(VI) reduction to Cr(III). The use of phytic acid (PA) as organic binder with combination of dual conducting polymer (Ppy-PA-Pani) was invigorating the adsorption efficiency than just single conducting polymer (Ppy-PA).

Adsorptive removal of Safranine T dye from aqueous solutions using sodium alginate-Festuca arundinacea seeds bio-composite microbeads

In this study, composite microbeads were prepared using Festuca arundinacea seeds and sodium alginate biopolymer at different ratios and utilized as sorbents for the sorption of Safranine T from wastewater. The sorbents were characterized by FTIR, SEM, XRD, and BET analysis. According to BET analysis, the specific surface area of the adsorbents was calculated to be 10.99 m2/g and the surface was found to be mesoporous. The optimum conditions for adsorption studies including initial pH (2-12), concentration (10-50 mg/L), contact time (0-150 min), and adsorbent mass (0.05 g/50 mL-0.25 g/50 mL) were determined at 25 °C. The raw data obtained from sorption tests were applied to Freundlich, Langmuir-1, Langmuir-2, Langmuir-3, Langmuir-4, Temkin, Toth, and Koble-Corrigan isotherm models. The best results were obtained from the Langmuir-2 and accordingly the qm values were calculated as 454.54, 833.33, and 625.00 mg/g for FA, FA-SA-20, and FA-SA-30 at 25 °C, respectively. Adsorption kinetic data illustrated that the process followed the PSO model. Reusability and desorption studies were performed for composite microbeads. Additionally, the thermodynamic studies were performed at 25, 35 and 45 °C. Considering all these results, it was seen that the FA-SA-20 composite had the highest adsorption capacity and the best desorption efficiency.

Effective Removal of Cd(II) from Aqueous Solutions Using Theobroma cacao Agro-Industrial Waste

Theobroma cacao agro-industrial waste (WTC) has been characterized and tested as an effective biosorbent to remove Cd(II) from aqueous media. At the optimum pH of 5.0, a maximum adsorption capacity of q_e,max = 58.5 mg g^-1 was determined. The structural and morphological characterization have been conducted by FTIR, SEM/EDX, and TGA measurements. The SEM/EDX results confirmed that the metals are adsorbed on the surface. C-O-C, OH, CH, NH, and C=O functional groups were identified by FTIR. TGA results were consistent with the presence of hemicellulose. Biosorption kinetics were rapid during the first 30 min and then reached equilibrium. The corresponding experimental data were well fitted to pseudo-first and -second order models, the latter being the best. The biosorption isotherm data were also well fitted to Temkin, Langmuir, and Freundlich models, showing that several sorption mechanisms may be involved in the Cd(II) biosorption process, which was characterized as exothermic (ΔH⁰ < 0), feasible, and spontaneous (ΔG⁰ < 0). In binary (Cd-Pb and Cd-Cu) and ternary (Cd-Pb-Cu) systems, Cu(II) and particularly Pb(II) co-cations exert strong antagonistic effects. Using HNO₃, effective good regeneration of WTC was obtained to efficiently remove Cd(II) up to three times.

KMnO4-oxidized whole pine needle based adsorbent for selective and efficient removal of cationic dyes

In the present study, we report the chemical modification of the dried and fallen pine needles (PNs) via a simple protocol using KMnO4 oxidation. The oxidized PNs (OPNs) were evaluated as adsorbents using some cationic and anionic dyes. The successful synthesis of OPNs adsorbent was characterized by various techniques to ascertain its structural attributes. The adsorbent showed selectivity for the cationic dyes with 96.11% removal (Pr) for malachite green (MG) and 89.68% Pr for methylene blue (MB) in 120 min. Kinetic models namely, pseudo-first order, pseudo-second order, and Elovich were applied to have insight into adsorption. Additionally, three adsorption isotherms, i.e., Langmuir, Freundlich, and Temkin were also applied. The dye adsorption followed a pseudo-second-order kinetic model with R2 > 0.99912 for MG and R2 > 0.9998 for MB. The adsorbent followed the Langmuir model with a maximum adsorption capacity (qm) of 223.2 mg/g and 156.9 mg/g for MG and MB, respectively. Furthermore, the OPNs showed remarkable regeneration and recyclability up to nine adsorption-desorption cycles with appreciable adsorption for both the dyes. The use of OPNs as an adsorbent for the removal of dyes from wastewater, therefore, provides an ecologically benign, low-cost, and sustainable solution.

Competitive adsorptive removal of promazine and promethazine from wastewater using olive tree pruning biochar: operational parameters, kinetics, and equilibrium investigations

This research aims to remove two phenothiazines, promazine (PRO) and promethazine (PMT), from their individual and binary mixtures using olive tree pruning biochar (BC-OTPR). The impact of individual and combinatory effects of operational variables was evaluated for the first time using central composite design (CCD). Simultaneous removal of both drugs was maximized utilizing the composite desirability function. At low concentrations, the uptake of PRO and PMT from their individual solutions was achieved with high efficiency of 98.64%, 47.20 mg/g and 95.87%, 38.16 mg/g, respectively. No major differences in the removal capacity were observed for the binary mixtures. Characterization of BC-OTPR confirmed successful adsorption and showed that the OTPR surface was predominantly mesoporous. Equilibrium investigations revealed that the Langmuir isotherm model best describes the sorption of PRO/PMT from their individual solutions with maximum adsorption capacities of 640.7 and 346.95 mg/g, respectively. The sorption of PRO/PMT conforms to the pseudo-second-order kinetic model. Regeneration of the adsorbent surface was successfully done with desorption efficiencies of 94.06% and 98.54% for PRO and PMT, respectively, for six cycles.