Biosorption of acid brown 14 dye to mandarin-CO-TETA derived from mandarin peels

Isotherm, kinetics and ANN analysis of methylene blue adsorption onto nitrogen doped Ulva lactuca Biochar

This study investigates the removal of methylene blue (MB) dye from aqueous solutions using a novel adsorbent, green algae (Ulva lactuca)-derived biochar-ammonia (NDULB), produced through activation with 85% sulfuric acid and hydrothermal treatment with ammonium hydroxide. The characterization of NDULB was carried out through various techniques, including BET surface area analysis and scanning electron microscopy, confirming its high surface area and effective porosity for dye adsorption. This work thoroughly examines the effects of initial MB dye concentration, solution pH, contact time, and NDULB dose on adsorption. The adsorption data were modeled using Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich isotherms, with the Freundlich model showing the best fit, indicating multilayer adsorption on a heterogeneous surface. According to the investigation's findings, with an initial MB concentration of 200 ppm and an NDULB dosage of 1.25 g L-1, the adsorption capacity at equilibrium (qe) is 966.31 mg g-1. Kinetic analysis revealed that the pseudo-second-order model provided the best fit for the experimental data, suggesting chemisorption as the dominant adsorption mechanism. The artificial neural network modeling has been studied and reported. The study clarifies the effects of multiple variables on adsorption, which might lead to key insights to enlighten the development of effective wastewater treatment strategies. The study demonstrates that NDULB offers a promising, sustainable alternative for MB dye removal in wastewater treatment, with significant implications for large-scale application.

Modelling of a new form of nitrogen doped activated carbon for adsorption of various dyes and hexavalent chromium ions

This study reports a new form of nitrogen-doped activated carbon (AC5-600) produced from a blend of sawdust (SD) and fish waste (FW) treated with urea and ZnCl2 for the adsorption of toxic metals and dyes. The adsorbent was also explored in the treatment of acid brown 14 (AB14) and acid orange 7 (AO7) dye molecules and hexavalent chromium (Cr6+) ions. The pH controls the sorption of individual contaminants, with an observed superlative % of individual contaminants removed at pH 1.5. Removal at pH was credited to the electrostatic interaction (EI) between the anion dyes and Cr6+ species at this pH and the protonated sites accessible on the AC5-600 adsorbent surface. Based on the error values obtained from the non-linear modelling (NLM) of the kinetic and isotherm models, the Elovich (ELM-AB14 and Cr6+), pseudo-first- (PFOM-AB14) and second-order models (PSOM-AB14, AO7 and Cr6+) and the Freundlich (FRHM) model were found to ideally define the sorption of the various contaminants. The determined maximum sorption capacity (Qm) based on the NLM was 1114, 1929 and 318 mg.g-1 for AB14 dye, AO7 dye and Cr6+ ions, respectively. Based on the computational adsorption calculations, the sorption energies for the AO7 and AB14 dyes were -4.492 and -8.090 eV and 2.563, 1.789, 1.226 and 1.928 eV for Cr2, CrO3, CrO4, and CrO4H species. AB14 and AO7 dyes and Cr6+ ions adsorption to synthesised AC5-600 was predicted employing the response surface methodology (RSM) and artificial neural network (ANN) models. The ANN model was more effective in predicting AB14 and AO7 dyes and Cr6+ ions adsorption than the RSM, and it was highly applicable in the sorption process.

Microwave-induced degradation of Congo red dye in the presence of 2D Ti3C2Tx MXene as a catalyst

In this research, the degradation of Congo red (CR) dye, as an organic pollutant in water, was investigated using microwave-induced reaction technology. This technology requires a microwave-absorbing catalyst and the 2D Ti3C2Tx MXene was synthesized for that purpose. The synthesized catalyst was characterized using XRD, SEM, TEM, EDX, BET, and XPS techniques. Results showed that the prepared 2D Ti3C2Tx MXene with a dosage of 50 mg degraded CR dye with an initial concentration of 25 ppm in an aqueous solution with a degradation percentage of approximately 99% in only 6 min. The parameters studied were catalyst dosage and initial CR dye concentration, which were found to have significant impacts on the degradation rate. When the catalyst dosage was increased significantly, the degradation rate increased significantly. On the other hand, when increasing the initial CR dye concentration, the degradation rate decreased. The degradation kinetics were studied, and the reaction followed the pseudo-first-order model. The rate constants obtained ranged from 0.04 to 0.83 min-1, varying according to the used catalyst dosage and initial CR dye concentration. The catalyst was stable and could be reused for up to five catalytic cycles without losing its degradation efficiency. The active species participating in the degradation process were determined using scavengers such as benzoquinone, Na-EDTA, and isopropyl alcohol. Optimization of the degradation parameters using a response surface methodology study concluded that a maximum degradation percentage could be reached when employing 35.30 mg of 2D Ti3C2Tx MXene and 29.07 ppm of CR dye solution.

Green synthesis of zinc oxide nanoparticles using Padina pavonica extract for efficient photocatalytic removal of methylene blue

Dye-laden wastewater poses a significant environmental and health threat. This study investigated the potential of green-synthesized zinc oxide nanoparticles (ZnO NPs), derived from Padina pavonica brown algae extract, for the removal of methylene blue (MB) dye. The hypothesis was that utilizing algal extract for ZnO NP synthesis would enhance adsorption capacity and photocatalytic activity for dye removal. The synthesized ZnO NPs, characterized by Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and Zeta Potential, demonstrated high adsorption capacity (Qm = 192.308 mg g-1) and excellent removal efficiency (> 98%) for MB at low dye concentrations. Langmuir isotherm and pseudo-second-order kinetic models best fit the experimental data, suggesting monolayer adsorption and chemisorption as the primary mechanisms. Notably, the green ZnO NPs exhibited greater photocatalytic activity under direct sunlight irradiation compared to other light sources. Additionally, these nanoparticles displayed antimicrobial properties against various bacteria, indicating potential for water disinfection. This research offers a sustainable and environmentally friendly approach for wastewater treatment utilizing green ZnO NPs for efficient dye removal and potential water disinfection applications.

Plant phytochemicals-mediated synthesis of zinc oxide nanoparticles with antimicrobial, pharmacological, and environmental applications

Nanotechnology is a fast-growing field with large number of applications. Therefore, the current study, was designed to prepare Zinc Oxide nanoparticles (ZnO NPs) from A. modesta leaves extract through a cost-effective method. The prepared NPs were characterized through UV-Vis Spectroscopy (UV-Vis), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscope (SEM), and energy dispersive X-ray (EDX). The XRD and DLS analysis revealed the hexagonal nanocrystalline nature of ZnO NPs. The FTIR results displayed multiple fictional groups and UV results confirmed its optical properties. The average size of the NPs was 68.3 nm with a band gap of 2.71 eV. The SEM images divulge a clover leaf shape of ZnO NPs. The EDX spectrum revealed the presence of zinc and oxygen. The prepared NPs showed excellent biomedical application. The highest antileishmanial activity was 68%, anti-inflammatory activity was 78%, total antioxidant capacity (TAC) was 79.1%, antibacterial potential (ZOI) 22.1 mm, and highest growth inhibition of 85 ± 2.1% against A. rabiei. The adsorption efficiency of 85.3% within 120 min was obtained. Conclusively ZnO NPs have shown potential biomedical and environmental applications and ought to be the more investigated to enhance their practical use.

Box–Behnken modeling of biodiesel production from Botryococcus braunii microalgae

This research aimed to model and optimize the growth factors and enhance the lipid yield from Botryococcus braunii microalgae, and to design a system for obtaining biodiesel from these lipids as this does not compromise food security. Botryococcus braunii, grown on a modified Chu‐13 medium, reached the stationary phase after 27 days with a maximum cell count of 265 × 104 cells mL−1 after 27 days and maximum biomass yield of 725 mg L−1 after 30 days on modified Chu‐13 medium, which was higher than growth on Basal SAG medium. The maximum lipid content (18.47%) and lipid yield (4.46 mg L−1day) were obtained when B. braunii was cultivated on modified Chu‐13 medium after 30 days. Gas chromatography (GC) analysis for the lipids indicated that the highest percentages of SFAs (51.03%) and lowest percentages of monounsaturated fatty acids (MUFAs) (36.47%) and polyunsaturated fatty acids (PUFAs) (12.49%) were obtained by culturing B. braunii on modified Chu‐13 medium. The effect of different growth parameters (N2 level, NaHCO3, and CO2 concentrations) on growth yield was modeled by using D‐optimal design response surface methodology (RSM).

Mandarin biochar-CO-TETA was utilized for Acid Red 73 dye adsorption from water, and its isotherm and kinetic studies were investigated

Environmental pollution is a major issue today due to the release of dyestuff waste into the environment through industrial wastewater. There is a need for affordable and effective adsorbents to remove harmful dyes from industrial waste. In this study, Mandarin biochar-CO-TETA (MBCOT) adsorbent was prepared and used to remove Acid Red 73 (AR73) dye from aqueous solutions. The efficiency of dye removal was influenced by various factors such as solution pH, contact time, initial AR73 dye concentration, and MBCOT dosage. All experiments were conducted at 25 ± 2 °C, and the optimal pH was determined to be 1.5. The optimal conditions for dye removal were found to be an AR73 dye concentration of 100 mg/L, an MBCOT dosage of 1.5 g/L, and a contact time of 150 min, resulting in a 98.08% removal rate. Various models such as pseudo-first-order (PFO), pseudo-second-order (PSO), film diffusion (FD), and intraparticle diffusion (IPD) were used to determine the adsorption kinetics of AR73 dye onto MBCOT. The results showed that the PSO model best explains the AR73 dye adsorption. Furthermore, Langmuir and Freundlich's isotherm models were studied to explain the adsorption mechanism using experimental data. The adsorption capacities at equilibrium (qe) in eliminating AR73 dye varied from 92.05 to 32.15, 128.9 to 65.39, 129.25 to 91.69, 123.73 to 111.77, and 130.54 to 125.01 mg/g. The maximum adsorption capacity (Qm) was found to be 140.85 mg/g. In conclusion, this study demonstrates that biochar produced from mandarin peels has the potential to be an effective and promising adsorbent for removing AR73 dye from water.

Copper(II) ion removal by chemically and physically modified sawdust biochar

The difference between physical activations (by sonications) and chemical activations (by ammonia) on sawdust biochar has been investigated in this study by comparing the removal of Cu(II) ions from an aqueous medium by adsorption on sawdust biochar (SD), sonicated sawdust biochar (SSD), and ammonia-modified sawdust biochar (SDA) with stirring at room temperature, pH value of 5.5–6.0, and 200 rpm. The biochar was prepared by the dehydrations of wood sawdust by reflux with sulfuric acid, and the biochar formed has been activated physically by sonications and chemically by ammonia solutions and then characterized by the Fourier transform infrared (FTIR); Brunauer, Emmett, and Teller (BET); scanning electron microscope (SEM); thermal gravimetric analysis (TGA); and energy-dispersive spectroscopy (EDX) analyses. The removal of Cu(II) ions involves 100 mL of sample volume and initial Cu(II) ion concentrations (conc) 50, 75, 100, 125, 150, 175, and 200 mg L−1 and the biochar doses of 100, 150, 200, 250, and 300 mg. The maximum removal percentage of Cu(II) ions was 95.56, 96.67, and 98.33% for SD, SSD, and SDA biochars, respectively, for 50 mg L−1 Cu(II) ion initial conc and 1.0 g L−1 adsorbent dose. The correlation coefficient (R2) was used to confirm the data obtained from the isotherm models. The Langmuir isotherm model was best fitted to the experimental data of SD, SSD, and SDA. The maximum adsorption capacities (Qm) of SD, SSD, and SDA are 91.74, 112.36, and 133.33 mg g−1, respectively. The degree of fitting using the non-linear isotherm models was in the sequence of Langmuir (LNR) (ideal fit) > Freundlich (FRH) > Temkin (SD and SSD) and FRH (ideal fit) > LNR > Temkin (SDA). LNR and FRH ideally described the biosorption of Cu(II) ions to SD and SSD and SDA owing to the low values of χ2 and R2 obtained using the non-linear isotherm models. The adsorption rate was well-ordered by the pseudo-second-order (PSO) rate models. Finally, chemically modified biochar with ammonia solutions (SDA) enhances the Cu(II) ions’ adsorption efficiency more than physical activations by sonications (SSD). Response surface methodology (RSM) optimization analysis was studied for the removal of Cu(II) ions using SD, SSD, and SDA biochars.

Fabrication of date palm kernel biochar-sulfur (DPKB-S) for super adsorption of methylene blue dye from water

A novel form of biochar was created by dehydration of Date palm kernel with 85% sulfuric acid. It was examined how the newly produced biochar (DPKB-S) affected the aqueous solution's capacity to extract Methylene Blue (MB) dye. The prepared DPKB-S was categorized by BET, BJH, FT-IR, SEM, EDX, DSC, and TGA analyses. The ideal pH for the MB dye adsorption by DPKB-S is 8. With 0.75 g L-1 of DPKB-S and an initial concentration of 50 ppm MB dye, Date Palm Kernel Biochar-Sulfur (DPKB-S) had the highest removal percentage of 100%. The Langmuir and Freundlich isotherm models were used to investigate the collected data. Freundlich model is the model that best covers MB dye adsorption in DPKB-S at low concentrations (0.75-1.25 g L-1) and the Langmuir model at high concentrations (1.5-1.75 g L-1). The Langmuir model maximum adsorption capacity (Qm) of the DPKB-S was 1512.30 mg g-1. Furthermore, a variety of error function models were applied to investigate the isotherm models derived data, including Marquardt's percent standard deviation (MPSD), the sum of absolute errors (EABS), the sum of the errors squared (ERRSQ), root mean square errors (RMS), Chi-square error (X2), the average relative error (ARE), average percent errors (APE), and hybrid error function (HYBRID). Kinetic data were calculated by intraparticle diffusion (IPD), pseudo-second-order (PSO), pseudo-first-order (PFO), and film diffusion (FD) models. A PSO rate model with a strong correlation (R2 = 1.00) largely regulated the adsorption rate. The removal mechanism of MB dye by DPKB-S is based on the principle that these positively charged dyes are attracted by electrostatic attraction forces due to the growth in the number of negatively charged regions at basic pH value. According to the results, DPKB-S shows promise as an affordable and competent adsorbent for the adsorption of MB dye. It can be used frequently without experiencing a discernible decrease in adsorption efficiency.

Biochar‐C‐TETA as a superior adsorbent to acid yellow 17 dye from water: isothermal and kinetic studies

Adsorbents from local materials with high adsorption capacity (Qm) are strongly needed. In this study, mandarin peels (MP) as a local waste material were refluxed in 80% sulfuric acid (H2SO4) to produce a novel biochar, which was oxidized by boiling in 50% hydrogen perioxide (H2O2) and then aminated via refluxing in tetraacetic acid (TETA) to produce mandarin biochar‐C‐TETA (MBCT). Fourier transform infrared (FTIR), Brunauer–Emmett–Teller (BET), Barrett–Joyner–Halenda (BJH), scanning electron microscopy (SEM), energy‐dispersive X‐ray (EDX), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and thermgravimetric analysis (TGA) studied various characterizations of MBCT. The optimal pH for AY17 dye absorption was discovered to be 1.5 using 0.75 g L−1 MBCT, the maximum absorption capacity predicted for the MBCT was 1250 mg g−1. The high new absorption peaks at 1439.89 and 1362.38 cm−1 in MBCT imply that amino groups were successfully generated onto the surface of MBCT due to TETA treatment. The experimental data were examined using the Langmuir (LNR) and Freundlich (FRH) isotherm models. The FRH best explained the experimental MBCT data. The pseudo‐first‐order (PFOM) and pseudo‐second‐order (PSOM) models, intraparticle diffusion (INDM) and film diffusion (FDM) models were applied to calculate the kinetic data. The PFOM rate model ideally defined the absorption of AY17 dye to MBCT with a linear regression coefficient (R2 > 0.99). The key mechanism for absorbing AY17 dye molecules to MBCT was chemisorption, which entails the distribution or exchange of electrons between the absorbent and the dye due to the valency force. According to the findings, the novel MBCT adsorbent had a remarkable adsorption capacity (Qm = 1250 mg g−1) and could be reused without losing its absorption effectiveness. © 2023 Society of Chemical Industry (SCI).

Enhanced Adsorption Performance Cross-Linked Chitosan/Citrus reticulata Peel Waste Composites as Low-Cost and Green Bio-Adsorbents: Kinetic, Equilibrium Isotherm, and Thermodynamic Studies

This study revealed the synthesis of cross-linked chitosan/Citrus reticulata peel waste (C/CRPW) composites that could be used as low-cost and green bio-adsorbents for the removal of Congo red (CR) dye from aqueous solutions. C/CRPW composites containing different amounts of Citrus reticulata peel waste (CRPW) and chitosan were prepared and cross-linked with glutaraldehyde. The composites were characterized by FESEM, EDS, FTIR, XRD, BET, and zeta potential measurements. The C/CRPW composites as a new type of bio-adsorbents displayed superior adsorption capability toward anionic CR molecules, and the adsorption capacities increased with the incorporation of CRPW. Effects of different ambient conditions, such as contact time, pH, adsorbent dosage, initial adsorbate concentration, and temperature, were fully studied. The conditions which obtained 43.57 mg/g of the highest adsorption capacity were conducted at pH 4 with an initial concentration of 100 mg/L, adsorbent dosage of 2.0 g/L, and contact time of 24 h at 328 K. The adsorption data was found to follow the pseudo-second-order kinetic model and the Freundlich isotherm model. According to the findings of this investigation, it was observed that the C/CRWP composites could be used as adsorbents due to their advantages, including the simple preparation process, being environmentally friendly, renewable, efficient, and low-cost.

Formation of self-nitrogen-doping activated carbon from Fish/sawdust/ZnCl2 by hydrothermal and pyrolysis for toxic chromium adsorption from wastewater

This study gives a description of the formation of self-nitrogen doped activated carbon (NDAC) by a novel way of employing fish meal (mixture of Atherina hepseetus and Sardina pilchardus of 60% protein) as nitrogen dopant, ZnCl₂ as impregnate agent, sawdust as carbon source and water with a mass ratio (2:1:1:12), which subjected to the hydrothermal process. The hydrothermal mixture was oven dried and carbonized under a flow of nitrogen for one h at 600, 700, and 800 °C. The characterization of NDAC was performed by using various analytical techniques analyses. The synthesized NDAC exhibited unique features such as microporous structure (1.84 ~ 2.01 nm), high surface area (437.51 ~ 680.86 m²/g), the volume of total pores (0.22 ~ 0.32 cm³/g) and nitrogen content (12.82 ~ 13.73%). Batch removal tests were achieved to investigate the impact of chromium ions starting concentration (100-400 mg/L), NDAC dose (0.5-2.5 g/L), pH and contact time (5-120 min). Such helpful characteristics of NDAC, particularly for NDAC600, were suitable to use as an excellent adsorbent for Cr⁶⁺ ions with a maximum adsorption capacity (Q_m) (769.23 mg/g), and the highest chromium ions adsorption uptake (81.18%) was obtained at pH value 1.5 at room temperature. Both Halsey and Temkin models fitted the adsorption data quite reasonably. The uptake of toxic chromium ions is best represented with pseudo-second-order rate kinetics data.

Electrospun cellulose acetate/activated carbon composite modified by EDTA (rC/AC-EDTA) for efficient methylene blue dye removal

The present study fabricated regenerated cellulose nanofiber incorporated with activated carbon and functionalized rC/AC3.7 with EDTA reagent for methylene blue (MB) dye removal. The rC/AC3.7 was fabricated by electrospinning cellulose acetate (CA) with activated carbon (AC) solution followed by deacetylation. FT-IR spectroscopy was applied to prove the chemical structures. In contrast, BET, SEM, TGA and DSC analyses were applied to study the fiber diameter and structure morphology, the thermal properties and the surface properties of rC/AC3.7-EDTA. The CA was successfully deacetylated to give regenerated cellulose nanofiber/activated carbon, and then ethylenediaminetetraacetic acid dianhydride was used to functionalize the fabricated nanofiber composite. The rC/AC3.7-EDTA, rC/AC5.5-EDTA and rC/AC6.7-EDTA were tested for adsorption of MB dye with maximum removal percentages reaching 97.48, 90.44 and 94.17%, respectively. The best circumstances for batch absorption experiments of MB dye on rC/AC3.7-EDTA were pH 7, an adsorbent dose of 2 g/L, and a starting MB dye concentration of 20 mg/L for 180 min of contact time, with a maximum removal percentage of 99.14%. The best-fit isotherm models are Temkin and Hasely. The outcome of isotherm models illustrates the applicability of the Langmuir isotherm model (LIM). The maximal monolayer capacity Qm determined from the linear LIM is 60.61 for 0.5 g/L of rC/AC3.7-EDTA. However, based on the results from error function studies, the generalized isotherm model has the lowest accuracy. The data obtained by the kinetic models' studies exposed that the absorption system follows the pseudo-second-order kinetic model (PSOM) throughout the absorption period.

Adsorption of direct blue 106 dye using zinc oxide nanoparticles prepared via green synthesis technique

Zinc oxide nanoparticles (ZnO-NPs) have in recent times shown effective adsorption capability for the confiscation of colour contaminants from aqueous environments (aquatic ecosystems or water bodies) due to the fact that ZnO contains more functional groups. Direct blue 106 (DB106) dye was selected for this present study as a model composite due to its wide range of uses in textiles (cotton and wools), woods, and paper industries, as well as their therapeutic applications, along with its potential for impairments. This study therefore focuses on the use of DB106 dye as a model composite due to its wide range of uses in textiles (cotton and wools), woods, and paper industries, as well as their therapeutic applications and their potential for impairments. Furthermore, the surface functionalization, shape, and composite pore size were revealed by TEM, FTIR, UV, and BET techniques. The current study uses green synthesis method to prepare ZnO-NPs as an adsorbent for the DB106 dye molecules adsorption under various conditions using the batch adsorption process. The adsorption of DB106 dye to the ZnO-NPs biosorbent was detected to be pH-dependent, with optimal adsorption of DB106 (anionic) dye particles observed at pH 7. DB106 dye adsorption to the synthesized ZnO-NPs adsorbent was distinct by means of the linearized Langmuir (LNR) and pseudo-second-order (SO) models, with an estimated maximum adsorption capacity (Qm) of 370.37 mg/g.

Adsorption of Cr6+ ion using activated Pisum sativum peels-triethylenetetramine

The adsorption of Cr6+ ions from water-soluble solution onto activated pea peels (PPs) embellished with triethylenetetramine (TETA) was studied. The synthesized activated TETA-PP biosorbent was further characterized by SEM together with EDX, FTIR and BET to determine the morphology and elementary composition, functional groups (FGs) present and the biosorbent surface area. The confiscation of Cr6+ ions to activated TETA-PP biosorbent was observed to be pH-reliant, with optimum removal noticed at pH 1.6 (99%). Cr6+ ion adsorption to activated TETA-PP biosorbent was well defined using the Langmuir (LNR) and the pseudo-second-order (PSO) models, with a determined biosorption capacity of 312.50 mg/g. Also, it was found that the activated TETA-PP biosorbent can be restored up to six regeneration cycles for the sequestration of Cr6+ ions in this study. In comparison with other biosorbents, it was found that this biosorbent was a cost-effective and resourceful agro-waste for the Cr6+ ion confiscation. The possible mechanism of Cr6+ to the biosorbent was by electrostatic attraction following the surface protonation of the activated TETA-PP biosorbent sites.