Sorbent Dosage Research Articles

Characteristics of Removal of Lead, Cadmium and Chromium from Soil Using Biosorbent and Biochar

The study proposed the use of aspen wood sawdust and biochar derived from this sawdust for the removal of Pb(II), Cd(II), and Cr(VI) ions from soil in systems containing single metals as well as a mixture of all the studied metals. The effectiveness of the applied sorbents was compared with the sorptive properties of activated carbon. The results showed that all the tested materials reduced the metal content in the soil, and the obtained biochar was able to sorb lead, cadmium, and chromium ions in both studied systems. The influence of the type of sorbent, its dose, process duration, and the impact of metal on the removal efficiency and sorption capacity was analyzed. A statistical analysis of the obtained results was also conducted, determining the influence of process parameters on the removal capabilities of metal ions. The highest Pb, Cd and Cr ion removal efficiencies were obtained in a 36-day process at a sorbent dose of 10%. Aspen sawdust, biochar and activated carbon removed 46%, 50% and 71% of Pb(II), 35%, 43% and 53% of Cd(II) and 15%, 27% and 38% of Cr(VI), respectively. In turn, the highest sorption capacity values were achieved in a 36-day process at a sorbent dose of 2%, obtaining results of 20.2 mg/g, 22.3 mg/g and 23.2 mg/g of Pb(II), 5.1 mg/g, 7.9 mg/g and 11.7 mg/g of Cd(II) and 3.8 mg/g, 5.8 mg/g and 8.5 mg/g of Cr(VI), respectively. It was found that both raw aspen wood sawdust and biochar derived from this wood are effective in removing toxic metal ions from soil, which presents a potential solution to their presence in the natural environment.

Facile and efficient sequestration of uranium using biomass from Saudi Arabia’s local date palms waste

Kingdom of Saudi Arabia has announced to utilize its domestic resources to enhance its future nuclear power capacity to a total of 17.6 GW by 2040. This ambitious plan is followed by mining and extraction of uranium from various approaches both physically and chemically. Therefore, an economical and efficient approach was devised for harvesting uranium content from aqueous solutions by using two bio-sorbent, i.e., date pit sawdust (DPS) and date palm biowaste (PDB). The DPS and PDB were analyzed with BET surface area, FT-IR, SEM, EDX, pHPZC and XRD techniques to examine the surface area, porosity, functional group on surface, morphology, point of zero charge of the materials and nature of materials respectively. Effect of parameters like sorbent dose, solutions pH, concentrations and time of contact on adsorption were studied in a batch method. The findings indicated that both DPS and PDB exhibited significant sequestration of U(VI) with maximum adsorption observed at 6 pH. However, PDB exhibited the maximum sorption percentage (78.80 %) and capacity (3.25 mg/g), followed by DPS (70.5 %, 2.47 mg/g, respectively), for uranium sequestration.

Design and Production of Functionalized Electrospun Fibers for Palladium Recovery.

Adsorption stands out as a leading wastewater treatment method for ion removal or recovery. Polymeric fibers, notably electrospun ones, are gaining prominence due to their high capacity and easy recovery. Electrospinning offers a cost-effective means to produce fibers with a large surface area and high adsorption capacity. These fibers can be further functionalized with chemical substances acting as specific ligands for metal ions, bolstering their adsorption capabilities. In this study, dithioester-functionalized electrospun fibers were synthesized as an alternative to conventional sorbents for palladium recovery from acidic chloride solutions, similar to those used in hydrometallurgical processes for platinum group metal recovery (Pd, Pt, Rh···) from spent catalysts. Fibers with identical chemical composition but varying morphology were examined to assess their impact on palladium adsorption efficiency (i.e., beads-free and beads-on-string morphologies). Experimental investigations involved model solutions with varying palladium concentration, temperature, acidity (adjusted with HCl content), and salinity (adjusted with NaCl), utilizing both pure and dithioester-functionalized fibers. Experimental results demonstrate enhanced adsorption efficiency at lower temperatures and in 0.1 M HCl, with a negligible influence from solution salinity. Moreover, both pure polymeric and dithioester-functionalized electrospun fibers exhibit highly efficient palladium recovery. Furthermore, under optimal conditions, starting from an 80 mg/L palladium solution, a 95% recovery of palladium can be achieved with a sorbent dosage below 4 g/L of functionalized electrospun fibers. The adsorption data are well described by the Langmuir isotherm model for the pure polymeric fibers. At the same time, the contribution of dithioesters has been separately accounted for to describe the behavior of functionalized electrospun fibers. Thermal recovery of palladium from the spent sorbents has also been investigated.

Using Zeolite Materials to Remove Pharmaceuticals from Water.

Pharmaceutical drugs, including antibiotics and hormonal agents, pose a significant threat to environmental and public health due to their persistent presence in aquatic environments. Colistin (KOL), fluoxetine (FLUO), amoxicillin (AMO), and 17-alpha-ethinylestradiol (EST) are pharmaceuticals (PhCs) that frequently exceed regulatory limits in water and wastewater. Current removal methods are mainly ineffective, necessitating the development of more efficient techniques. This study investigates the use of synthetic zeolite (NaP1_FA) and zeolite-carbon composites (NaP1_C), both derived from fly ash (FA), for the removal of KOL, FLUO, AMO, and EST from aquatic environments. Batch adsorption experiments assessed the effects of contact time, adsorbent dosage, initial concentration, and pH on the removal efficiency of the pharmaceuticals. The results demonstrated that NaP1_FA and NaP1_C exhibited high removal efficiencies for all tested pharmaceuticals, achieving over 90% removal within 2 min of contact time. The Behnajady-Modirshahla-Ghanbary (BMG) kinetic model best described the adsorption processes. The most effective sorption was observed with a sorbent dose of 1-2 g L-1. Regarding removal efficiency, the substances ranked in this order: EST was the highest, followed by AMO, KOL, and FLUO. Sorption efficiency was influenced by the initial pH of the solutions, with optimal performance observed at pH 2-2.5 for KOL and FLUO. The zeolite-carbon composite NaP1_C, due to its hydrophobic nature, showed superior sorption efficiency for hydrophobic pharmaceuticals like FLUO and EST. The spectral analysis reveals that the primary mechanism for immobilizing the tested PhCs on zeolite sorbents is mainly due to physical sorption. This study underscores the potential of utilizing inexpensive, fly ash-derived zeolites and zeolite-carbon composites to remove pharmaceuticals from water effectively. These findings contribute to developing advanced materials for decentralized wastewater treatment systems, directly addressing pollution sources in various facilities.

Enhanced capacity of thiol-functionalized sugarcane bagasse and rice husk biochars for arsenite sorption in aqueous solutions

The utilization of biowastes for producing biochar to remove potentially toxic elements from water represents an important pathway for aquatic ecosystem decontamination. Here we explored the significance of thiol-functionalization on sugarcane bagasse biochar (Th/SCB–BC) and rice husk biochar (Th/RH–BC) to enhance arsenite (As(III)) removal capacity from water and compared their efficiency with both pristine biochars (SCB–BC and RH–BC). The maximum As(III) sorption was found on Th/SCB–BC and Th/RH–BC (2.88 and 2.51 mg g−1, respectively) compared to the SCB–BC and RH–BC (1.51 and 1.40 mg g−1). Relatively, a greater percentage of As(III) removal was obtained with Th/SCB–BC and Th/RH–BC (92% and 83%, respectively) at a pH 7 compared to pristine SCB–BC and RH–BC (65% and 55%) at 6 mg L−1 initial As(III) concentration, 2 h contact time and 1 g L−1 sorbent dose. Langmuir (R2 = 0.99) isotherm and pseudo-second-order kinetic (R2 = 0.99) models provided the best fits to As(III) sorption data. Desorption experiments indicated that the regeneration ability of biochars decreased and it was in the order of Th/SCB–BC (88%) > Th/RH–BC (82%) > SCB–BC (77%) > RH–BC (69%) up to three sorption–desorption cycles. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy results demonstrated that the thiol (-S–H) functional groups were successfully grafted on the surface of two biochars and as such contributed to enhance As(III) removal from water. Spectroscopic data indicated that the surface functional moieties, such as -S–H, − OH, − COOH, and C = O were involved to increase As(III) sorption on thiol-functionalized biochars. This study highlights that thiol-grafting on both biochars, notably on SCB–BC, enhanced their ability to remove As(III) from water, which can be used as an effective technique for the treatment of As from drinking water.Graphical

Preparation and potential of chitosan-based/Al2O3 green hydrogel composites for the removal of methyl red dye from simulated solution.

Different dyes are discharged into water streams, causing significant pollution to the entire ecosystem. The present work deals with the removal of acid red 2 dye (methyl red-as an anionic dye) by green sorbents based on chitosan derivatization. In this regard, two classes of chitosan derivatives-a total of six-were prepared by gamma irradiation at 30kGy. The first group (group A) constitutes a crosslinked chitosan/polyacrylamide/aluminum oxide with different feed ratios, while the second group, identified as group B, is composed of crosslinked carboxymethyl chitosan/polyacrylamide/aluminum oxide with different ratios. Glycerol was added to soften the resultant hydrogels. The products were characterized by different tools, including FTIR for confirming the chemical modification, TGA for investigating their thermal properties, and XRD for verifying their crystalline structure. The morphology of the prepared derivatives was studied through SEM, while their topography before and after dye adsorption was monitored via the AFM. The removal efficiencies of the prepared sorbents were verified at different operation conditions, such as pH, temperature, adsorbent dose, initial concentration of dye solutions, and contact time. The data revealed that the optimum conditions for maximum dye uptake were as follows: pH 4, contact time 120min, 0.1-g sorbent dose, and 50-ppm dye concentration. Additionally, the prepared sorbents demonstrated potent adsorption capacity and removal efficiency. It was found that the elements of the second group displayed higher performance than their counterparts. The data showed also that the adsorption process best fits with the Freundlich model and obeyed pseudo-first-order kinetic isotherm. In addition, the synthesized composites showed observable antibacterial potency toward E. coli as a Gram-negative bacterium and S. aureus as a Gram-positive bacterium.

Applications of Ion Exchange in Environmental Remediation: Removal of Heavy Metals From Wastewater

ABSTRACTThe concern over heavy metal contamination and its impact on human health and the environment has led to a growing interest in cost‐effective and sustainable remediation technologies. Ion exchange is recognized as an efficient method for removing heavy metal ions from wastewater. This study focused on the removal of heavy metal ions (Ni, Cu, Zn, and Pb) from aqueous solutions using the extended batch equilibrium technique. Experimental trials were conducted using Purolite C100, a strong acid ion‐exchange resin, to assess the influence of various treatment parameters such as pH, contact time, sorbent dosages, and initial heavy metal concentrations on the removal efficiency. The results indicated that significant treatment equilibrium could be achieved within 1 h. Notably, pH levels between 5 and 6 had a significant impact on heavy metal removal, with adsorption capacities of 71, 67, 66, and 62 mg/g for Ni, Cu, Zn, and Pb, respectively. Furthermore, the equilibrium data obtained from the batch experiments were well fitted with Langmuir, Freundlich, and pseudo‐first‐order kinetic models. Statistical analysis revealed a strong correlation with the Langmuir isotherm model, highlighting its superiority over the Freundlich isotherm and pseudo‐first‐order kinetic models.

Employing a magnetic chitosan/molybdenum disulfide nanocomposite for efficiently removing polycyclic aromatic hydrocarbons from milk samples

This study aimed to develop a highly efficient nanocomposite composed of magnetic chitosan/molybdenum disulfide (CS/MoS2/Fe3O4) for the removal of three polycyclic aromatic hydrocarbons (PAHs)—pyrene, anthracene, and phenanthrene. Novelty was introduced through the innovative synthesis procedure and the utilization of magnetic properties for enhanced adsorption capabilities. Additionally, the greenness of chitosan as a sorbent component was emphasized, highlighting its biodegradability and low environmental impact compared to traditional sorbents. Factors influencing PAH adsorption, such as nanocomposite dosage, initial PAH concentration, pH, and contact time, were systematically investigated and optimized. The results revealed that optimal removal efficiencies were attained at an initial PAH concentration of 150 mg/L, a sorbent dose of 0.045 g, pH 6.0, and a contact time of 150 min. The pseudo-second-order kinetic model exhibited superior fitting to the experimental data, indicating an equilibrium time of approximately 150 min. Moreover, the equilibrium adsorption process followed the Freundlich isotherm model, with kf and n values exceeding 7.91 mg/g and 1.20, respectively. Remarkably, the maximum absorption capacities for phenanthrene, anthracene, and pyrene on the sorbent were determined as 217 mg/g, 204 mg/g, and 222 mg/g, respectively. These findings underscore the significant potential of the CS/MoS2/Fe3O4 nanocomposite for efficiently removing PAHs from milk and other dairy products, thereby contributing to improved food safety and public health.

Diesel soot as a cost effective and efficient adsorbent of hazardous Methylene Blue-An environmental benign approach

Diesel soot - a byproduct formed by combustion of hydrocarbons is a threat to the health of society and environment. Herein, it is attempted to convert it into a resource material by utilizing it as an efficient adsorbent of dyes such as methylene blue aiming at industrial waste water treatment. The diesel soot is collected from an engine exhaust, washed with ethanol and dried. It is characterized for its chemical nature, crystallinity, surface area and morphology through Raman spectroscopy, XRD, BET, SEM and TEM techniques. Adsorption of methylene blue molecules by this soot carbon nanoparticles is studied as a function of sorbent dosage, dye concentration, pH and contact time. The diesel soot carbon nanoparticles were found to have an adsorption efficiency of 98.5 % with 26.6 mg/g adsorption capacity and requires very less contact time. Column operations with the carbon soot shows the possible industrial application in removal of dye contaminants in large quantities of water without any reduction in efficiency upto eight cycles.

Poprawa zdolności sorpcyjnej i zastosowania biosorbentu poprzez immobilizację

The water contamination by toxic metal ions is a worldwide environmental problem. High concentrations are hazardous for all living organisms, causing many disorders and diseases and ecological damages to the surroundings. Biosorption is an innovative technology that employs inactive and dead biomass (bacteria, fungi, algae, biowaste) for the recovery of metals from aqueous solutions. Sulphate-reducing bacteria utilization is one of the options how to prepare applicable sorbent which removes metal ions from water. This material is created as a consequence of bacteria metabolism in anaerobic environment. The use of freely suspended biomass is often impractical and has some disadvantages. In contrast to this, application of immobilized biomass shows more benefits including increased mechanical strength, resistance to chemical environment, easy separation of cells and effluents, high biomass performance and repeated use in many adsorption/desorption cycles. Cell entrapment is the most widely used method for immobilization. In this technique, the cells are enclosed in a polymeric matrix which is porous enough to allow diffusion of substrate to the cells. The aim of this work was to examine and compare the sorption ability of biogenic iron sulphides created by sulphate-reducing bacteria in “free” and “entrapped” form. Precipitates were synthesized in reagent bottles with bacteria culture and growth media Postgate C, at 30 °C during 60 days, subsequently dried and analysed. Prepared samples were immobilized using sodium alginate. Sorption of cadmium from model solutions was realized in 100 ml Erlenmeyer flasks, with sorbent dose 1 g/l, during 24 hours. During experiments, the samples showed a satisfying stability and maximum adsorption capacity achieved 38 mg/g. The results refer to good sorption properties of immobilized samples and their potential for further practical use.

Efficient chromium removal from leather industrial wastewater in batch experimental study: Green synthesis and characterization of zinc oxide nanoparticles using Ficus benghalensis extracts

The urgent need to address the severe environmental risk posed by chromium-contaminated industrial wastewater necessitates the development of eco-friendly cleanup methodologies. Utilizing the Ficus benghalensis plant extracts, the present study aims to develop green zinc oxide nanoparticles for the removal of Cr metal ions from wastewater. The leaves of Ficus benghalensis, often known as the banyan tree, were used to extract a solution for synthesizing ZnO NPs. These nanoparticles were developed with the goal of efficiently eliminating chromium (Cr) from industrial effluents. Batch studies were carried out to assess the efficiency of these synthesized ZnO NPs in treating leather industrial effluent, with aiming for optimal chromium removal. This involved measuring the nanoparticles' capacity to adsorb Cr ions from wastewater samples by comparing chromium levels before and after treatment. Removal efficiency for Cr was estimated through the batches such as optimization of pH, contact time, initial Cr concentration and sorbent dose of ZnO NPs were of the batches. These synthesized ZnO NPs were found to be successful in lowering chromium levels in wastewater to meet permissible limit. The nanoparticles exhibited their highest absorption capacity, reaching 94 % (46 mg/g) at pH 4, with a contact time of 7 hours with the optimum sorbent dose of 0.6 g/L. Hence, the excellent adsorption capabilities of these nanoparticles, together with their environmentally benign manufacturing technique, provide a long-term and efficient solution for chromium-contaminated wastewater treatment. Its novel nature has the potential to significantly improve the safety and cleanliness of water ecosystems, protecting the both i.e. human health and the environment.

Efficient removal of Cd2+ ions and methylene blue from aqueous solutions by polyanionic sodium alginate-derived hydrogel

Considering the purification technology based on the fabrication of efficient adsorbents for the effective removal of water contaminants, we developed a polyanionic superabsorbent hydrogel for its application in the adsorption of cadmium ions (Cd2+) and methylene blue (MB). The hydrogel was prepared by graft copolymerization of methacrylic acid, acrylamide, and 2-acrylamido-2-methyl-1-propanesulfonic acid onto sodium alginate. The hydrogel structure, thermal stability, surface morphology, and surface area were studied using FT-IR, SEM, EDX, TGA, and BET techniques.The hydrogel capacity to remove Cd2+ MB from aqueous solutions was investigated at different contact times, pH, sorbent dosage, contaminant concentrations, temperature salinity, and ion selectivity. To understand the hydrogel sorption behavior, different adsorption kinetics and isotherms models were employed. The hydrogel exhibited impressive efficacy in the removal of Cd2+ and MB ions, achieving removal efficiencies of up to 87% and 97.5%, respectively, under a sorbent dosage of 0.15 g/100 mL and a temperature of 25°C. Utilizing the Langmuir isotherm model, the maximum sorption capacities were determined to be 526 mg/g for cadmium ions and 131.5 mg/g for methylene blue. Regeneration experiments confirmed the reusability of the hydrogel, highlighting its potential as an effective adsorbent for Cd²⁺ and MB dye.

Banana peels as a green bioadsorbent for removing metals ions from wastewater

Bioadsorption using agricultural waste offers a promising approach for removing toxic metals from wastewater. This study explores the potential of chemically activated banana peels (BPs) as a green and cost-effective bioadsorbent for Cu(II) and Zn(II) removal. Fourier-transform infrared (FTIR) spectroscopy revealed the presence of functional groups like alcohols, phenols, and amino acids on activated BPs, potentially responsible for metal ion binding. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of cavities on the BPs surface and the existence of oxygen and potassium. The adsorption capacity of BPs was investigated under various conditions, including pH, contact time, sorbent dosage, metal concentration, and temperature. This study used Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich (D–R) isotherm models to describe the equilibrium results of Cu (II) and Zn (II) adsorption. The Langmuir isotherm model best described the adsorption process, suggesting monolayer coverage of metal ions on the BPs surface. Maximum adsorption capacities were 3.2 mg g−1 for Cu(II) and 2.8 mg g−1 for Zn(II), demonstrating the effectiveness of BPs in metal removal. Kinetic studies indicated pseudo-first-order (PFO) behavior for Cu(II) and pseudo-second-order (PSO) behavior for Zn(II) adsorption. Thermodynamic analysis revealed a spontaneous and exothermic process (negative Gibbes free energy (ΔG°) and enthalpy (ΔH°) with decreased randomness [negative entropy (ΔS°)] at the biosorption interface. Finally, the BPs sorbent was successfully applied to remove different metal ions from real wastewater samples collected from the El Wadi drain.

Identification of influential parameters and conditions in heavy metals adsorption onto Cal-LDH-PC using optimization approaches of RSM and Taguchi

Adsorption process plays an important role in the remediation of heavy metals (HMs) from wastewater. A laboratory trial was conducted to investigate effective parameters for improving the bio-adsorption removal of HMs. SEM, EDX, BET, and FTIR techniques were applied to characterize the calcined layer double hydroxide (Cal-LDH), pectin (PC), and Cal-LDH-PC composite prepared from Licorice pomace. The adsorption of zinc (Zn) cadmium, nickel (Ni) and lead (Pb) onto the most efficient sorbent was investigated using RSM methodology with operational factors such as concentration, reaction time, sorbent dose, and pH. The results related to FTIR showed that Cal-LDH-PC had the highest number of functional groups. Based on the SEM results Cal-LDH had a low surface area (9.36 m2 g-1) and a small pore size (9.22 nm). After the modification process (Cal-LDH-PC), the values of surface area and pore size increased by 13-fold (120 m2 g-1) and 1.5-fold (18 nm), respectively. Cal-LDH had high adsorption performance, more cavities, stability, various functional groups, and excessive carbon and oxygen content, which make it efficient and powerful in removing HMs from wastewater. The optimal condition for achieving the removal efficiency (RE%) values of metals was determined to be 80.79 mg L−1, 100 min, 0.167 g L−1, and 9 for concentration, reaction time, sorbent dose, and pH, respectively. Maximum adsorption capacity and RE (%) were 300 mg g−1 and 99% for Zn. According to the results concentration had a major impact on RE% (except for Ni), while for Ni, adsorbent dose had the most significant impact. The present study introduced Cal-LDH-PC prepared from Licorice pomace as a capable, useful and economical sorbent for HMs removal from polluted environments. Taguchi's statistical method is distinguished as an economic method with easier interpretation, while the RSM approach is more accurate, and it can also check the interaction of parameters.

Mesoporous magnetic biochar derived from common reed (Phragmites australis) for rapid and efficient removal of methylene blue from aqueous media

A novel mesoporous magnetic biochar (MBC) was prepared, using a randomly growing plant, i.e., common reed, as an exporter of carbon, and applied for removal of methylene blue (MB) from aqueous solutions. The prepared sorbent was characterized by nitrogen adsorption/desorption isotherm, saturation magnetization, pH of point of zero charges (pHPZC), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The obtained MBC has a specific surface area of 94.2 m2 g−1 and a pore radius of 4.1 nm, a pore volume of 0.252 cm3 g−1, a saturation magnetization of 0.786 emu g−1, and a pHPZC of 6.2. Batch adsorption experiments were used to study the impact of the physicochemical factors involved in the adsorption process. The findings revealed that MB removal by MBC was achieved optimally at pH 8.0, sorbent dosage of 1.0 g L−1, and contact time of 30 min. At these conditions, the maximum adsorption was 353.4 mg g−1. Furthermore, the adsorption isotherm indicated that the Langmuir pattern matched well with the experimental data, compared to the Freindlich model. The ∆G was − 6.7, − 7.1, and − 7.5 kJ mol−1, at 298, 308, and 318 K, respectively, indicating a spontaneous process. The values of ∆H and ∆S were 5.71 kJ mol−1 and 41.6 J mol−1 K−1, respectively, suggesting endothermic and the interaction between MB and MBC is van der Waals type. The absorbent was regenerated and reused for four cycles after elution with 0.1 mol L−1 of HCl. This study concluded that the magnetic biochar generated from common reed has tremendous promise in the practical use of removing MB from wastewater.Graphic

A facile in-situ ultrasonic-assisted synthesis of terephthalic acid-layered double hydroxide/bacterial cellulose: Application for eco-friendly analysis of multi-residue pesticides in vineyard soils

A novel nanostructure biosorbent comprised of bacterial cellulose (BC) and a Cu-Cr layered double hydroxide (LDH) intercalated with terephthalic acid (TPA) was prepared using the in-situ coprecipitation method. The synthesized TPA/CuCr-LDH@BC sorbent was used in quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction of multiclass pesticides (nine insecticides, five acaricides, one herbicide, and one fungicide) followed by gas chromatography-mass spectrometry. The extraction factors such as type and volume of eluent, sorbent dosage, adsorption and desorption times, sample pH, and salt were optimized. The sorbent was analyzed with field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and adsorption/desorption isotherms to check its chemical structure, crystallinity, and porosity. Matrix effect (15.3–19.6 %), linearity (20–2000 µg/L, r2 > 0.9982), limits of quantification (6–12 µg/L), and enrichment factor (42–65) were calculated. The efficiency and accuracy of the developed method were assessed with the analysis of five vineyard soil samples and the resulting recoveries were in the range of 60–130 % (RSD%=3.5–12.9). The green aspects of the procedure were evaluated by the Complex-GAPI, the AGREE, and the Analytical Eco-Scale tools. This study describes the first-time synthesis of TPA/CuCr-LDH@BC composite and its application as sorbent material for the microextraction of multi-residue pesticides in agricultural soils.

Lead (Pb) Sorption Kinetics by Clay Minerals: Bentonite and Zeolite

Background: Heavy metal pollution chiefly lead (Pb) causes various environmental disequilibrium and health hazards. Immobilization of lead (Pb) usingclay minerals is cost effective for metal remediation due to their higher surface area and negative charges. Methods: This study was taken up to assess the Pb removal potentials of bentonite and zeolite from contaminated water and to study the effect of sorbent dosage, initial Pb2+ concentrations and incubation time intervals on Pb adsorption and desorption was studied. Result: Zeolite was effective in immobilising Pb (78.0%) than bentonite (70.9%) which increased with increasing sorbent dosage and time intervals. The pseudo second-order kinetic model described the Pb adsorption precisely. Chemisorption was the dominant mechanism operating in aqueous solution system, hence, it could be concluded that zeolite can be utilized as an efficient sorbent for wastewater treatment.

Ultrasonic-induced grafted lanthanum sulfide decorated multi-walled carbon nanotube onto bacterial cellulose applied for adsorption of pesticides in environmental waters

A new biosorbent was fabricated by modification of bacterial cellulose biopolymer grafted with lanthanum sulfide decorated carboxylated multiwall carbon nanotube (La2S3@MWCNT@BC). The sorbent was employed in a green alternative dispersive-solid phase extraction of a variety of 14 pesticides in environmental water samples. The analyses were performed using GC-µECD. The properties and structure of La2S3@MWCNT@BC nanocomposite were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and adsorption-desorption isotherms. The composition of the sorbent was also investigated to evaluate the adsorptive properties of its constituents. The impact of various parameters influencing extraction efficacies such as sorbent dose, adsorption time, sample pH, ionic strength, and desorption conditions was investigated. The method was validated by specificity, matrix effect % (-0.4 to -7.4), enrichment factor (4–10), limits of quantification (0.007–0.31 μg L−1), matrix-matched calibration linearity (0.01–200 µg L−1), determination coefficients (r2=0.9921–0.9998), and precision. The optimized method was applied for the analysis of multiclass pesticides in seven environmental and drinking waters and the recoveries were obtained in the 81–108 % range with RSDs of 2.5–4.7 %. This paper is the first report on the synthesis and use of La2S3@MWCNT@BC nanocomposite to extract pesticides from different water samples. The greenness of the procedure was evaluated by the AGREE protocols.

A novel sponge composite of chitosan-sodium tripolyphosphate-melamine for anionic dye Orange II removal

Since the potential carcinogenic, toxic and non-degradable dyes trigger serious environmental contamination by improper treatment, developing novel adsorbents remains a major challenge. A novel high efficiency and biopolymer-based environmental-friendly adsorbent, chitosan‑sodium tripolyphosphate-melamine sponge (CTS-STPP-MS) composite, was prepared for Orange II removing with chitosan as raw material, sodium tripolyphosphate as cross-linking agent. The composite was carefully characterized by SEM, EDS, FT-IR and XPS. The influence of crosslinking conditions, dosage, pH, initial concentration, contacting time and temperature on adsorption were tested through batch adsorption experiments. CTS-STPP-MS adsorption process was exothermic, spontaneous and agreed with Sips isotherm model accompanying the maximum adsorption capacity as 948 mg∙g−1 (pH = 3). Notably, the adsorption performance was outstanding for high concentration solutions, with a removal rate of 97 % in up to 2000 mg∙L−1 OII solution (100 mg sorbent dosage, 50 mL OII solution, pH = 3, 289.15 K). In addition, the adsorption efficiency yet remained 97.85 % after 5 repeated adsorption-desorption cycles. The driving force of adsorption was attributed to electrostatic attraction and hydrogen bonds which was proved by adsorption results coupled with XPS. Owing to the excellent properties of high-effective, environmental-friendly, easy to separate and regenerable, CTS-STPP-MS composite turned out to be a promising adsorbent in contamination treatment.

Synthesis of novel magnetic hydroxyapatite-biomass nanocomposite for arsenic and fluoride adsorption.

A magnetic nanocomposite of hydroxyapatite and biomass (HAp-CM) was synthesized through a combined ultrasonic and hydrothermal method, aiming for efficient adsorption of arsenic (As) and fluoride (F-) from drinking water in natural environments. The characterization of HAp-CM was carried out using TG, FTIR, XRD, SEM, SEM-EDS, and TEM techniques, along with the determination of pHpzc charge. FTIR analysis suggested that coordinating links are the main interactions that allow the formation of the nanocomposite. XRD data indicated that the crystalline structure of the constituent materials remained unaffected during the formation of HAp-CM. SEM-EDS analysis revelated a Ca/P molar ratio of 1.78. Adsorption assays conducted in batches demonstrated that As and F- followed a PSO kinetic model. Furthermore, As adsorption fitting well to the Langmuir model, while F- adsorption could be explained by both Langmuir and Freundlich models. The maximum adsorption capacity of HAp-CM was found to be 5.0mgg-1 for As and 10.2mgg-1 for F-. The influence of sorbent dosage, pH, and the presence of coexisting species on adsorption capacity was explored. The pH significantly affected the nanocomposite's efficiency in removing both pollutants. The presence of various coexisting species had different effects on F- removal efficiency, while As adsorption efficiency was generally enhanced, except in the case of PO43-. The competitive adsorption between F- and As on HAp-CM was also examined. The achieved results demonstrate that HAp-CM has great potential for use in a natural environment, particularly in groundwater remediation as a preliminary treatment for water consumption.