Fabrication and characterization of Araucaria gum/calcium alginate composite beads for batch and column adsorption of lead ions

Okra mucilage embedded chitosan@ graphene oxide composite for efficient adsorption of mercuric ions: Kinetic and thermodynamic studies

The development of novel adsorbents with superior adsorption performance presents an effective strategy to tackle the growing issue of mercuric ion (Hg2+) contamination. This study focuses on the fabrication of three efficient adsorbents: graphene oxide (GO), graphene oxide/chitosan (GCS), and graphene oxide/chitosan reinforced with okra mucilage (OGS). The synthesized adsorbents were characterized using various physicochemical techniques, which confirmed that OGS possessed a surface area of 456.9 m2/g, a pHPZC of 6.7, and a pore radius of 2.30 nm. The observations were successfully explained utilizing Langmuir adsorption isotherm and the pseudo-second order kinetics. OGS showcased a superior adsorption capability of 538.5 mg/g for Hg2+ at 2.0 g/L dose, 25 min of agitation period at 25 °C, and a pH of 5. Following six rounds of adsorption-desorption, roughly 6.0, 5.7, and 2.2 % diminished performance was detected for GO, GCS, and OGS, respectively. Thermodynamic investigations proved that Hg2+ ions adsorb spontaneously via an endothermic mechanism. The column adsorption capacity was 305.8 mg/g at a Hg2+ concentration of 100 mg/L, with a flow rate of 15 mL/min and a bed height of 2 cm. Both the Yoon-Nelson and Thomas models match significantly with the column adsorption data of Hg2+ ions on OGS. Our results demonstrated that OGS exhibits excellent adsorption performance, highlighting its potential for application in water remediation.

A novel Araucaria gum/carrageenan/Mg-Fe LDH nanocomposite for advanced batch and fixed-bed adsorption of mercuric ions from aqueous medium

In the present work, several meticulously planned batch and fixed-bed adsorption experiments were performed to compare the adsorption capacities of the synthesized magnesium-ferric layered double hydroxide (Mg-Fe LDH, MFL), carrageenan/Mg-Fe LDH nanocomposite (MFC), and Araucaria gum/carrageenan/Mg-Fe LDH nanocomposite (MFAC) for mercuric ion removal from aqueous medium. Various physicochemical approaches were conducted to characterize the fabricated adsorbents, proving the successful incorporation of potassium κ-carrageenan and Araucaria gum on the LDH surface. The relatively greater particle size (130 nm), irregular pore distribution, average pore radius (3.2086 nm), and pHPZC (6.25) of MFAC were mainly responsible for its superior Hg2+ adsorption. Through a series of batch adsorption tests, Hg2+ adsorption on the MFAC nanocomposite exhibited a maximum adsorption capacity of 505.74 mg g-1 at 20 °C, pH 6, and a solid dosage of 2 g L-1 after 30 min. Several kinetics and isotherms were well-fitted for the adsorption process. Fixed-bed column tests proved that MFAC achieved 550.50 mg g-1 at a bed height of 1 cm, a Hg2+ solution concentration of 80 mg L-1, and a flow rate of 30 mL min-1 at 20 °C and pH 6 over 300 min. Thus, MFAC can be efficiently applied in wastewater treatment, offering major support for further research into practical applications.

Araucaria gum embedded kaolinite/ferric xanthan composite for enhanced adsorption of atrazine: Kinetic, thermodynamic, and column studies

Herbicides contribute significantly to water contamination, causing serious environmental and public health problems. The current study considers the creation of three adsorbents, ferric xanthan beads (X), ferric xanthan gum/kaolinite composite (KX), and xanthan gum/kaolinite modified with Araucaria gum (AKX), as powerful adsorbents for atrazine eradication from aqueous medium. Modern analytical tools were employed to characterize the fabricated adsorbents, which demonstrated that AKX has acceptable surface area (14.44 m2/g), with mesopores structure. The fabricated adsorbents were applied in a static adsorption procedure to remove atrazine, with varying parameters. Meanwhile, the column adsorption process focuses on the influence of bed height on atrazine removal by AKX. The results from the batch adsorption showed that AKX reached a maximum adsorption capacity (284.8 mg/g). The batch adsorption of atrazine was effectively modeled by the pseudo-first order, Elovich, Langmuir, and Temkin models for all the adsorbents. Thermodynamic studies revealed that the atrazine adsorption process is exothermic, physical, and occur spontaneously. The desorption efficiency for (X, KX, and AKX) reduced by only 15.9, 5.1, and 3.0 %, respectively, after 10 rounds of adsorption-desorption. Yoon-Nelson and Thomas models effectively applied breakthrough curves for atrazine column adsorption. AKX achieved a maximum column adsorption capacity of 384.0 mg/g under conditions of 20 mL/min flow rate, 1.5 cm bed height, and 80 mg/L initial atrazine concentration.

A versatile alginate aerogel with spatially separated sorption sites for simultaneously and collaboratively scavenging Pb(II) and tetracycline in wastewater: Insight into behavior and mechanisms in the mixture system

Alleviating combined pollution caused by heavy metals and antibiotics is of great significance for ecological sustainability and human health. It is still quite challenging to simultaneously and efficiently scavenge both pollutants due to their completely different physicochemical properties and the fierce competition between multi-pollutants faced by traditional adsorbents. In present work, a novel alginate-based aerogel microbead (GO/Fe3+-Ca2+-Alg) with specific sorption sites toward these two sorts of pollutants was fabricated via a 'multi-site coupling' strategy. It was found that multifarious sorption sites in the composite synergistically enhanced removal performance of Pb(II) and TC. The adsorption process of Pb(II) was better described by pseudo-second-order kinetics model (R2 = 0.968-0.989) and Langmuir isotherm model (R2 = 0.966-0.996). The maximum adsorption capacity of Pb(II) and TC in their individual systems was 268.04 and 1664.04 mg/g, respectively, superior to most reported sorption materials. Interestingly, in Pb(II)-TC binary system, Pb(II) capture was enhanced by co-existing TC and its adsorption capacity was positively correlated with concentration of co-existing TC, assigning to the formation of ternary complex (adsorbent-TC-Pb(II) or adsorbent-Pb(II)-TC). However, the removal of TC was enhanced with 10 mg/L Pb(II), and hindered with 20-80 mg/L Pb(II) because of the competition effect of Pb(II) and TC. Sequential adsorption as well as Zeta potential experiments were further performed to verify mutual interaction between Pb(II) and TC. More importantly, the as-designed material was applied in treatment of simulated aquaculture wastewater with removal rates above 80 %, showing its great potential for simultaneous and collaborative elimination of Pb(II) and TC in complex wastewater. This work provided unique insights into designing integrated adsorbents for wastewater bearing heavy metals and antibiotics.

Electrospun hybrids of Delonix regia gum/calcium alginate/thiosemicarbazide for the adsorption of mercuric ions from aqueous medium

The accumulation of Hg2+ in the environment threatens both human health and the biosphere. The development of cost-effective and efficient nanofibers for removing Hg2+ offers a different solution to this issue. Herein, calcium alginate nanofiber (GF), Delonix regia gum/alginate nanofiber (DGF), and thiosemicarbazide/Delonix regia gum/alginate nanofiber (TDGF) were successfully synthesized by electrospinning technique then crosslinking with 2 % calcium chloride solution. The manufactured composites nanofibers included several functional groups that might interact with Hg2+. The nanofibers were mesoporous nanomaterials with a surface area of 49.8 m2/g and total pore volume of 0.0324 cm3/g for TDGF nanocomposite, which was beneficial for improving adsorption capacity. The adsorption kinetic data of the nanofibers toward Hg2+ were well-fitted with Langmuir isotherm model, and pseudo-second-order model provided a very good description of the process. The optimum adsorption capacity for GF, DGF, and TDGF was 302.29, 334.90, and 485.82 mg/g, respectively. The adsorption thermodynamics were investigated to better understand the adsorption process. This analysis identified the physical, endothermic, spontaneous, and advantageous mechanisms involved in removing Hg2+. All the prepared nanofibers (GF, DGF, and TDGF) demonstrated great reusability with only 8.9, 9.8, and 3.3 % decrease in the removal efficiency, respectively. In general, the TDGF nanofiber composite shows great promise for detoxifying complicated wastewater.

Utilization of a constructed nanohydroxyapatite/Arabic gum/alginate composite based on cuttlefish bone for the removal of cadmium ions

The purpose of this work is to explore the efficacy of cadmium ions (Cd2+) removal employing adsorption onto manufactured solid nanomaterials. This study synthesized three nanosolid adsorbents: nanohydroxyapatite based on cuttlefish bone (NHAPs), nanohydroxyapatite/alginate beads (HC), and nanohydroxyapatite/Arabic gum/alginate as triple biocomposite (HGC) beads. Various physicochemical techniques were used to study the morphological, physical, and chemical characteristics of solid nanoadsorbents. The fabricated triple composite (HGC) showed a higher surface area (564.9 m2/g), acceptable pHPZC (7.3), and average TEM particle size of 150 nm. These manufactured materials were used as solid adsorbents to eliminate cadmium ions from wastewater under various test conditions such as shaking time, sample dose, pH, starting Cd2+ concentration, and temperature. The data revealed that HGC had a greater adsorption capacity (246.10 mg/g) at 16 °C. The adsorption of Cd2+ was well applied by nonlinear pseudo-first order and Elovich as kinetic investigations, besides Langmuir and Temkin models according to adsorption isotherm investigations onto all the samples. Based on the values of reduced chi-square value (ꭓ2), the pseudo-first order and Langmuir models are more accepted models for Cd2+ adsorption. The thermodynamic study revealed that the adsorption process of Cd2+ is endothermic and spontaneous. After eight adsorption and desorption operations, the highest batch adsorption capacity was reduced by 1.45 % for NHAPs, 5.49 % for HC, and 5.24 % for HGC. Our findings demonstrated that HGC has outstanding adsorption capacity, quick kinetics, and high effectiveness promising composite in water treatment applications.

Natural gums-derived hydrogels for adsorptive removal of heavy metals: A review

This review explores advancing and refining hydrogels derived from natural gums for heavy metal ion adsorption, focusing on their efficiency, capacity, and influencing parameters. The high adsorption capacity of these hydrogels, with values reaching up to 384.6 mg/g (Pb2+) and 203.7 mg/g (Cu2+), is linked to functional moieties like -COOH and -OH, which bind to metal ions through electrostatic interactions, exchange of ions, and coordination mechanisms. Adsorption efficiency is governed by conditions such as duration of contact, temperature, and pH. Temperature studies imply that adsorption occurs through an endothermic mechanism, with positive ΔH values and negative ΔG values, validating the spontaneity and efficiency of the process. Adsorption isotherms, including Langmuir and Freundlich models, have shown promising fits, with a high correlation coefficient (r2 > 0.9). The kinetic study reveals that the adsorption follows pseudo-second-order kinetics, implying a chemisorption mechanism. The occurrence of interfering ions (e.g., Na+, Ca2+) can reduce adsorption efficiency, but their impact is minimal at lower concentrations. Overall, gum-based hydrogels provide an eco-conscious and reliable approach for metal ion removal in aqueous solutions, showing potential for large-scale environmental applications. Further studies focusing on improving adsorption capacity and scalability are recommended to enhance their practical utility in wastewater treatment.

A novel fabrication of graphitic carbon nitride/chitosan composite modified with thiosemicarbazide for the effective static and dynamic adsorption of Pb2+ from aqueous media

In this work, graphitic carbon nitride (g-C3N4) prepared by thermal treatment, graphitic carbon nitride/chitosan (GCS), and graphitic carbon nitride/chitosan embedded thiosemicarbazide (TGCS) were developed as an effective solid adsorbent. The fabricated adsorbents were characterized by nitrogen adsorption, ATR-FTIR, TGA, XRD, ζ potential, SEM, and TEM, where TGCS composite had a higher surface area (536.79 m2/g), total pore volume (0.4152 cm3 /g), average pore size (3.09 nm), and pHPZC (6.4). TGCS revealed a Langmuir adsorption capacity of 329.61 mg/g for Pb2+ at an adsorbent dosage of 1.5 g/L, pH 5, 45 min of shaking, and 23 °C. The experimental results were applied well by pseudo-second-order kinetic and Langmuir isotherm. Through the first five adsorption-desorption cycles, only 12.2, 6.2, and 5.1 % decline in efficiency were noted for g-C3N4, GCS, and TGCS, respectively. Column adsorption capacity (qo, mg/g) was determined to be 132.24 mg/g at bed height 3 cm, flow rate of 80 mL/min, and 80 mg/L as initial Pb2+ concentration. Based on the lower reduced chi-square values (ꭓ2 × 10-4, 3.8810-12.9000) and the higher correlation coefficients (R2, 0.9917-0.9979), the Yoon-Nelson and Thomas models suggested an acceptable match for the breakthrough curve. Our findings suggested that TGCS had great adsorption capacity, strong selectivity, and quick kinetics, indicating its potential for water treatment applications.

Efficient Hg2+ adsorption using a silk fibroin/MOF-2/alginate composite: Kinetics and thermodynamics

The effective adsorption of (mercuric ions) Hg2+ onto synthesized and characterized composite materials based on calcium alginate (CG), zinc metal-organic farmwork (MOF-2), and silk fibroin powder (SF) has been reported in this study. Under various application conditions, the adsorption capacities of silk fibroin powder/zinc metal organic framework/alginate composite (ZSG) were compared with those of the other individual solid materials. These solid adsorbents materials were characterized by various physicochemical techniques. Characterization tools proved the well-advanced physiochemical properties of the formed composite with 298.6 m2/g as surface area, pore radius of 35.91 Å, 0.10 % swelling ratio, 6.50 as pHPZC, and the presence of various surface chemical functional groups. The maximum Hg2+adsorption capacity was found to be 453.67 mg/g for ZSG as calculated from nonlinear Langmuir adsorption model. Studies on kinetics and thermodynamics revealed that the pseudo-second-order model, Elovich, and Van 't Hoff models fit the adsorption process. It was discovered that the adsorption process was endothermic, physical, and spontaneous. Total dissolved solids (TDS) were found to have an adverse effect on the adsorption capacity. According to findings, the developed composite shows promise as a reusable solid adsorbent for metal cations.

Efficient lead ion removal from aqueous solutions for wastewater treatment using a novel cross-linked alginate-rice husk ash-graphene oxide-chitosan nanocomposite

This research introduces an innovative composite, the cross-linked alginate-rice husk ash-graphene oxide-chitosan nanoparticles (CL-ARCG-CNP), designed for the effective adsorption of lead ions (Pb2+) in water treatment applications. Comprehensive characterization was performed using techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), High-Resolution Transmission Electron Microscopy (HR TEM), Selected Area Electron Diffraction (SAED), Atomic Force Microscopy (AFM), Thermogravimetric Analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. These analyses revealed notable structural and morphological features. The CL-ARCG-CNP composite demonstrated a significant surface area of approximately 148.44 m2/g, achieving an impressive adsorption capacity of 242.5 mg/g and a removal efficiency of 95.2 % after 240 min of contact duration. The adsorption process conformed to the Freundlich isotherm model (R2: 0.998) and the pseudo-second-order kinetic model (R2: 0.9992). Thermodynamic studies confirmed the spontaneity and endothermic nature of the adsorption process. Reusability tests showed that the composite could be reused for up to five cycles with minimal loss in adsorption capacity. These findings indicate that the CL-ARCG-CNP composite is highly effective for the removal of Pb2+ ions from aqueous solutions, making it a promising material for wastewater treatment.

Nitrogen-Doped Weathered Coal for the Efficient Adsorption of Lead: Adsorption Performance and Mechanisms

The development of widely sourced and efficient adsorbents is crucial for the adsorption of lead from wastewater. A novel adsorbent, N-doped weathered coal (NWC), was prepared in this study using weathered coal as the precursor and triethylenetetramine (TETA) as the N-source. The adsorption performance and behavior of Pb(II) on NWC were investigated using batch adsorption experiments. The results demonstrated that NWC has an efficient adsorption performance towards Pb(II), with a maximum monolayer adsorption capacity of 216.32 mg g-1 (25 °C). The adsorption process was spontaneous and endothermic, and the importance of chemisorption was observed. The adsorption mechanisms of NWC were also analyzed based on its physicochemical structure before and after the Pb(II) adsorption and desorption experiments. The N and O functional groups, acting as electron donors, promoted coordination with Pb(II), making complexation the dominant mechanism. Its contribution to the adsorption mechanism could reach 44.81%. NWC is a promising material for both wastewater treatment and the resource utilization of weathered coal.

Fabrication and characterization of xanthan gum nanofibers reinforced with thiosemicarbazide: adsorption of Pb2+ from an aqueous medium

In this study, electrospinning was used to fabricate xanthan gum (XF) and thiosemicarbazide/xanthan gum (TXF) nanofibers crosslinked with ferric ions for effective Pb2+ adsorption. The produced nanofibers were investigated using several physicochemical methods. Both XF and TXF demonstrated thermal stability up to 800 °C, with mass losses of 79% and 75%, respectively. TXF had a surface area of 153.4 m2 g-1 and point of zero charge at pH 6.7. ATR-FTIR analysis revealed the existence of surface chemical functional groups such as -NH2, -NH, and -C[double bond, length as m-dash]S owing to thiosemicarbazide reinforcement. XF and TXF displayed maximum adsorption capacities of 211.65 and 289.18 mg g-1 at pH 6, 2.0 g L-1 nanofiber dose, 22 °C, and after 40 min of contact shaking time. The adsorption process was investigated using several nonlinear adsorption models as well as by desorption and reusability investigations. Thermodynamics examination demonstrated the spontaneous, endothermic physisorption of Pb2+ onto XF and TXF. Ethylenediaminetetraacetic acid was selected as the most efficient eluent for Pb2+ removal from the nanofiber surfaces, with desorption efficiencies of 100% and 97% for XF and TXF, respectively. TXF and XF revealed remarkable sustainability, with reductions in adsorption capacities of only 7% and 12% of the initial removal efficiency after 10 cycles of adsorption/desorption, respectively. As a solid adsorbent for the removal of heavy metal cations, the produced TXF nanofiber demonstrated great sustainability and environmental friendliness.

High-performance copper terephthalic acid metal-organic framework/gum Arabic/carrageenan composite beads for efficient lead(II) removal from aqueous solutions

Lead (Pb(II)) contamination poses a significant threat to human health and the environment. This study investigates a new approach for Pb(II) removal from polluted water using copper terephthalic acid metal-organic framework/gum Arabic/potassium carrageenan (MGC) composite beads. We synthesized copper terephthalic acid MOF, potassium carrageenan beads, and MGC composite beads to evaluate their adsorption potential. Characterization of the synthesized adsorbents was performed using TGA, nitrogen adsorption/desorption, ATR-FTIR, zeta potential, SEM, and TEM analyses, revealing that MOF > MGC > KG in thermal stability. The MGC composite exhibited a high specific surface area (398.03 m2/g) with mesopores and diverse functional groups, alongside a pH of zero point charge (pHpzc) of 6.8 and a small particle size (20 nm). The maximum Langmuir adsorption capacity for Pb(II) removal by MGC reached 374.7 mg/g under optimized conditions (20 °C, pH 5, 60 min shaking time, 3.0 g/L adsorbent dosage). The adsorption data fit well with the Pseudo-First-Order kinetic model and Langmuir and Dubinin-Radushkevich isotherm models. The adsorption process was physical, favorable, and endothermic. EDTA was used as a desorption agent, showing that the composite beads retained 97 % efficiency after ten cycles, highlighting MGC's potential as a sustainable strategy for Pb(II) remediation.

Fabrication of thiosemicarbazide-modified biochar/carrageenan composite beads based on Eichhornia crassipes for effective removal of Pb (II) from aqueous medium

Several biomasses have been applied as environmentally friendly substitutes to produce biochar, which can be utilized to remediate effluents that contain inorganic chemicals. This study applied water hyacinth (Eichhornia crassipes) as a foundation source for the assembly of thiosemicarbazide-modified biochar (BC), which then was modified with potassium carrageenan (KC). Thiosemicarbazide-modified biochar (BC), potassium carrageenan (KC), and thiosemicarbazide-modified biochar/carrageenan composite beads (BKC) were described by several physicochemical methods. The adsorption of Pb (II) onto the three solid adsorbents was investigated under various experimental conditions. The BKC composite beads revealed a surface area of 687.43 m2/g and a mesoporous structure. The best adsorption conditions were found to be 25 min as an equilibrium time, 1.2 g/L of adsorbent dose, and a solution pH of 5 at a temperature of 15 °C. The pseudo-second-order, Elovich kinetic models, Langmuir, and Temkin isotherms were well familiar to the experimental data, inferring that the progression was physical monolayer adsorption onto the homogenous surface. The highest capacity of Pb (II) adsorption onto BKC was 460.45 mg/g at 15 °C. Thermodynamic measurements proved that adsorption was a spontaneous process and endothermic in the case of BC and BKC while exothermic for KC. Furthermore, BKC showed high reusability conditions.

Fabrication of graphitic carbon nitride/gum Arabic/potassium carrageenan composite for efficient adsorption of erythromycin: Kinetic and thermodynamic studies

Erythromycin (ERY) molecules are robust to the environment and hard to remove due to their aromatic structure. Nowadays, numerous researches have reported that the ERY amount in water is above the standard level and its removal is necessary. Here, we prepared three solid adsorbents: graphitic carbon nitride (g-C3N4), potassium carrageenan beads (Cr), and graphitic carbon nitride/gum Arabic/potassium carrageenan composite (g-ACr). Several techniques such as XRD, SEM, TEM, TGA, ATR-FTIR, Zeta potential, and N2 adsorption were employed to characterize the fabricated adsorbents. Five essential factors of adsorbent dose, initial ERY concentration, contact time, temperature, and pH were optimized to investigate the batch adsorption of ERY. The maximum adsorption capacity of 356.12 mg/g was attained by g-ACr composite at an adsorbent dose of 1.25 g/L, contact time of 6 h, and pH 7 at 15 °C. The data showed that the experimental findings exhibited the best agreement with Langmuir, Temkin, and DR isotherm models, in addition to the kinetic models of pseudo-second-order, Elovich, and intra-particle diffusion. The evaluated thermodynamic factors designated that the ERY adsorption is endothermic, physisorption, favorable, and spontaneous process. The g-ACr reusability displayed a decline in the adsorption capacity after seven adsorption/desorption runs by 5.7 %. Finally, this work outcomes depict that g-ACr composite is an efficient reusable adsorbent for ERY elimination from wastewater.

Microwave Synthesis of Fluorescent Carbon Quantum dots from Araucaria Heterophylla Gum: Application in Drug Detection

This study employed a green microwave synthesis technique to produce carbon quantum dots (CQDs) from araucaria heterophylla gum extract. The produced CQDs emit a distinct blue fluorescent light, contributing a remarkable quantum yield of 14.69%. Their average particle size measures at 1.62 ± 0.39 nm. Furthermore, these CQDs demonstrate excellent water solubility and maintain high fluorescence stability despite ionic strength, pH and time variations. Moreover, we present here for the first time that the synthesized CQDs demonstrate a rapid, exceptionally sensitive, and discerning fluorescence quenching phenomenon (IFE) concerning Cefprozil (CPR). The fluorescent probe was sensitive and specific with good linear relationships for CPR in the 0-18 µM range. The limit of detection for relationships for CPR was 2.51 µM. This study provides novel opportunities for producing high-quality luminescent CQDs that meet the requirements for various biological and environmental applications.

Biochar/Delonix regia seed gum/chitosan composite as efficient adsorbent for the elimination of phenol from aqueous medium

In this study, biochar (BC) from Delonix regia pods peel and gum from Delonix regia seed (SG) were prepared, and also biochar/chitosan composite (BCS) and biochar/Delonix regia seed gum/chitosan composite (BCGS) were fabricated for the efficient adsorption of phenol. Various characterization tools such as SEM, TEM, ATR-FTIR, TGA, zeta potential, and textural investigation were studied to examine the features of the synthetized adsorbents, confirming their positive construction. It was fully studied how necessary factors, comprising pH, dose of adsorbent, contact shaking time, initial phenol concentration, and temperature influenced adsorption behavior. An obvious rise of the adsorption capacity from 60.16 to 165.20 mg/g was achieved by the modification of biochar with Delonix regia seed gum and chitosan under ideal circumstances of 2 h contact duration, pH 7, 15 °C, and a dose of 2.0 g/L. The phenol adsorption was well applied by Langmuir, Temkin, Dubinin-Radushkevich, and Sips isotherms, in addition to nonlinear pseudo-second-order kinetic model. Furthermore, the physisorption, endothermic, and spontaneous process was illustrated by thermodynamic investigation. Additionally, the fabricated adsorbents could be effectively used and regenerated without main losses of only 7.5, 4.6, and 4.0 % for BC, BCS, and BCGS, respectively in the removal percentage after seven cycles of application.

Fabrication of melamine formaldehyde/graphene oxide composite for efficient static and dynamic adsorption of lead ions from aqueous medium

The present work discusses the synthesis, characterization, and environmental applications of graphene oxide (GO), melamine formaldehyde resin (MF), and melamine formaldehyde/graphene oxide composite (MGO) for the efficient removal of Pb2+ from aqueous medium via batch and column procedures. TGA, XRD, TEM, zeta potential, nitrogen adsorption/desorption, ATR-FTIR, and other characterization techniques revealed that MGO is characterized by a greater surface area (609 m2/g), total pore volume (1.0106 cm3/g), pHPZC (6.5), and the presence of various surface chemical functional groups. The synthesized solid adsorbents were used in both static and dynamic adsorption processes to remove Pb2+, with varying application parameters such as pH, starting concentration, adsorbent dosage, and shaking time in the case of static adsorption method. While through the column adsorption process the effects of column bed height, flow rate, and starting Pb2+ were taken into consideration. Results of the batch adsorption demonstrated that MGO had the highest Langmuir adsorption capacity (201.5 mg/g), and the adsorption fit the nonlinear Langmuir adsorption model and Elovich kinetic models. The adsorption of Pb2+ onto all prepared solid materials is endothermic, spontaneous, and physical in nature, as demonstrated by thermodynamic studies. Column adsorption of Pb2+ well fitted by Thomas and Yoon Nelson nonlinear adsorption models. MGO showed a maximum column adsorption capacity of 168 mg/g when applying 4 cm, 15 mL/min, and 150 mg/L as bed height, flow rate, and initial Pb2+, respectively. With only a 12.6% reduction in its adsorption capacity, column regeneration showed that MGO exhibited a high degree of reusability even after five cycles of adsorption/desorption studies.

The application of P-modified biochar in wastewater remediation: A state-of-the-art review

Phosphorus modified biochar (P-BC) is an effective adsorbent for wastewater remediation, which has attracted widespread attention due to its low cost, vast source, unique surface structure, and abundant functional groups. However, there is currently no comprehensive analysis and review of P-BC in wastewater remediation. In this study, a detailed introduction is given to the synthesis method of P-BC, as well as the effects of pyrolysis temperature and residence time on physical and chemical properties and adsorption performance of the material. Meanwhile, a comprehensive investigation and evaluation were conducted on the different biomass types and phosphorus sources used to synthesize P-BC. This article also systematically compared the adsorption efficiency differences between P-BC and raw biochar, and summarized the adsorption mechanism of P-BC in removing pollutants from wastewater. In addition, the effects of P-BC composite with other materials (element co-doping, polysaccharide stabilizers, microbial loading, etc.) on physical and chemical properties and pollutant adsorption capacity of the materials were investigated. Some emerging applications of P-BC were also introduced, including supercapacitors, CO2 adsorbents, carbon sequestration, soil heavy metal remediation, and soil fertility improvement. Finally, some valuable suggestions and prospects were proposed for the future research direction of P-BC to achieve the goal of multiple utilization.