Maximum Adsorption Capacity Research Articles

Monocomponent Biosorption of Copper Ions (II) onto Nanocrystalline Cellulose from Coconut Husk Fibers

Introduction: Nanocrystalline cellulose (NCC) is one of the most suitable cellulose derivatives for the treatment of wastewater. Various agricultural wastes have been used for the extraction of NCC. Coconut wastes have been widely studied as potential adsorbents for the removal of pollutants, including dyes and heavy metals. Methods: In this work, nanocrystalline cellulose (NCC) was successfully isolated from coconut husk fibers through alkaline pretreatment accompanied by sulfuric acid hydrolysis. Then, the ability of NCC to adsorb Cu2+ from aqueous solution in batch studies was investigated. Results: Results indicated that the optimal hydrolysis parameters were achieved at 50° C for 45 min with 64% sulfuric acid to extract NCC as rod-like particles with diameters between 4-10 nm. The potential of NCC as a biosorbent to remove copper ions (Cu2+) from aqueous solution was investigated in terms of batch mode and maximum adsorption capacity (qm) of 79.491 mg/g of Cu2+. The adsorption efficiency of Cu2+ions increased with an increase in the adsorbent dosage, decreased with an increase in the initial concentration of contaminant, and increased with the contact time. Under optimal conditions, adsorption kinetic followed a pseudo-second-order kinetic model and the adsorption isotherm fitted most closely with the Langmuir model. Conclusion: According to a literature review, NCC from coconut husk fibers has not been used for the adsorption of heavy metals, mainly copper ions. This study shows that NCC from coconut husk fibers can be used as a low-cost and environmentally friendly adsorbent for the removal of Cu2+ from aqueous solutions.

Performance of metakaolin-based geopolymer molecular sieve microspheres on dynamic recovery of Cu (II)

This study reports the in-situ transformation of geopolymers into molecular sieve using a method with mild conditions. The application of geopolymer zeolites for dynamic adsorption in continuous fixed beds has been less studied, and the application of adsorbents after adsorption has been less studied. Different metakaolin-based geopolymer molecular sieve microspheres (NaA-MSM, SOD-MSM) were prepared by in-situ conversion of metakaolin as raw material and NaOH as an alkali activator. The continuous fixed-bed adsorption performance was evaluated by varying the influent flow rate, initial metal concentration, and adsorbent dosage. The maximum adsorption capacities of NaA-MSM and SOD-MSM for Cu (II) were 698.14 and 523.84 mg·g−1, respectively. In the simulated solution of real lake water, the adsorption capacities of NaA-MSM and SOD-MSM for Cu (II) were 202.94 and 154.97 mg·g−1, respectively. The results show that the synthesized molecular sieve is an excellent adsorbent for Cu (II)-containing wastewater, and the application design of recycling heavy metals in wastewater by adsorption technology and degrading dyes has been successfully constructed.

Magnetically recyclable mesoporous carbon/zirconia composites for highly efficient removal of Cr(III) organic complexes from high salinity water: adsorption behavior and mechanism

ABSTRACT In this study, zirconia-functionalized magnetic core-shell mesoporous carbon composites (Fe3O4@C-ZrO2) were synthesized for the effective removal of Cr(III)-EDTA in high-salinity wastewater. Fe3O4@C-ZrO2 with Fe3O4 as a magnetic core and ZrO2 embedded in a mesoporous carbon skeleton were prepared by the sol-gel method in the nano-casting stage, which can be magnetically separated. The presence of ZrO2 on the adsorbents enhanced the adsorption of Cr(III)-EDTA and the maximum adsorption capacity of Fe3O4@C-ZrO2 was 16.21 mg·g−1 at pH = 3.0, which is remarkably higher than that of Fe3O4@C (3.65 mg·g−1). Fe3O4@C-ZrO2 has a strong anti-interference capability for cations in water, which can exhibit effective adsorption properties in presence of high concentration cations and anions (80 mmol·L−1) and high salt/complexant agent environments. Cr(III)-EDTA removal by adsorption of Fe3O4@C-ZrO2 was mainly through the formation of ternary complexes between ZrO2 in Fe3O4@C-ZrO2 and carboxylic acid groups in Cr(III)-EDTA. The Cr(III)-EDTA saturated Fe3O4@C-ZrO2 can be easily regenerated in 0.1 mol·L−1 NaOH than in 0.1 mol·L−1 HCl and still demonstrated an effective adsorption capacity for Cr(III)-EDTA after three repeated cycles. The results reflect the effective removal of Cr(III)-EDTA by Fe3O4@C-ZrO2 in high-salinity water, providing a new method for removing heavy metals in complex water.

Two‐Dimensional Copper‐Based Metal‐Organic Framework for Efficient Removal of Methylene Blue from Wastewater

Metal‐organic frameworks (MOFs) can effectively remove methylene blue (MB) from wastewater due to their abundant adsorption sites and multi‐level pores. In this paper, a copper‐based MOF: {[Cu·(L)·(H2O)]·(DMF)}n (1) (H2L = 2‐hydroxyterephthalic acid; DMF = N,N‐dimethylformamide), was synthesized by hydrothermal synthesis method. X‐ray single crystal diffraction showed that a two‐dimensional structure was formed by the carboxyl group of L2‐ in 1 took μ2‐η1：η1 bridged two adjacent Cu(II). In this two‐dimensional structure, the coordinated water molecules and hydroxyl group on L2‐ were distributed on the surface of 1. Thus, it had abundant adsorption sites. The transmission electron microscopy (TEM) of copper‐based MOF nano adsorbent showed that the particle diameter of the nano adsorbent prepared by a cell fragmentation apparatus was about 50 nm. The performance of the copper‐based MOF nano adsorbent in adsorbing MB indicated that the optimal adsorbent dosage was 0.20 g/L and the solution pH was 6. Under the optimal experimental conditions, its maximum adsorption capacity for MB was 143.3 mg/g, which was superior to most MOFs adsorbents. The adsorption thermodynamic analysis showed that the copper‐based MOF nano adsorbent at 25 ‐ 45 ℃ was an exothermic (△H < 0) , and spontaneous (△G < 0) process.

Evaluating SiO2/Al2O3/poly(acrylic acid-co-glycidyl methacrylate) composite as a novel adsorbent for cobalt(II) radionuclides

Abstract A novel SiO2/Al2O3/poly(acrylic acid-co-glycidyl methacrylate), SiO2/Al2O3/P(AA-co-GMA), composite was synthesized and evaluated for its effectiveness in adsorbing Co(II) ions from aqueous solutions. The composite was analyzed using various techniques including FTIR, SEM, TGA, DTA, and XRD. The composite displays a high specific surface area of 17.451 m2/g, exceeding that of the corresponding copolymer, which measures 0.236 m2/g. Batch adsorption experiments were conducted to investigate the factors influencing the adsorption capacity of the composite for Co(II) ions. In the pH experiments, it was found that at a solution pH of 3.4, the P(AA-co-GMA) copolymer alone showed limited capability in adsorbing Co(II) ions, achieving only 3.82 mg/g. However, upon integration of SiO2/Al2O3 into the polymer matrix, the composite exhibited a significantly enhanced adsorption capacity of 103.54 mg/g. The adsorption process followed a pseudo-second-order kinetic model and attained equilibrium within 60 min. The Langmuir isotherm model was found to best describe the adsorption behavior, with a maximum adsorption capacity of 217.86 mg/g. The adsorption of Co(II) was significantly affected by the ionic strength, especially with Al3+ displaying a more pronounced impact on the adsorption of Co(II) ions compared to Na+, Ca2+, and Mg2+. Thermodynamic studies indicate that the adsorption process was spontaneous and endothermic. Overall, the SiO2/Al2O3/P(AA-co-GMA) composite material displayed significant adsorption ability for Co(II) ions, making it a suitable option for further development as an effective adsorbent in water treatment applications.

Removal of trivalent chromium ions in model contaminated groundwater using hexagonal boron nitride as an adsorbent

The feasibility of using hexagonal boron nitride (h-BN) to treat heavy metal Cr(III) from model contaminated groundwater was evaluated in this study by adsorption experiments and characterizations. To the best of our knowledge, this study is the first attempt to conduct the adsorption of Cr(III) by h-BN under various experimental conditions such as exposure time, ratio of adsorbates and adsorbents, solution pH, background ions with different ionic strength, and the presence of humic acids (HA) in model contaminated groundwater. The optimized h-BN showed excellent maximum adsorption capacity (i.e., 177 mg ∙ g−1) when the concentrations of Cr(III) and h-BN were 10 and 10 mg ∙ L−1, respectively. Subsequently, we confirmed there was a negligible change in the adsorption performance of Cr(III) by h-BN in the presence of co-ions (i.e., K and Mg) in concentrations in a range from 50 to 1000 mg ∙ L−1. Furthermore, the adsorption performance of Cr(III) gradually improved with HA concentrations from 2.5 to 25 mg ∙ L−1. Interestingly, the maximum adsorption performance of Cr(III) by both HA and h-BN increased until 500 mg ∙ g−1 in the presence of 25 mg ∙ L−1 HA. The adsorption mechanism was clarified by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Additionally, we successfully confirmed that h-BN could be reused until five cycles. On the basis of the adsorption performance results and characterizations, h-BN can be utilized as an efficient and practical adsorbent to treat Cr(III) in groundwater treatment.

Preparation of highly microporous activated carbon by utilizing inherent iron in coal through CO2 and steam co-activation for improving CO2 capture and methylene blue removal

Pore-tailoring by utilizing the inherent iron mineral in coal for highly microporous activated carbon (AC) preparation for boosting adsorption ability is a promising strategy. In this work, AC-XFeS2 (X indicates the contents of pyrite in coal, 0–3 wt.%) was prepared via blending demineralized Taixi coal and pyrite and followed by CO2 and steam co-activation. The iron minerals transformation, AC physicochemical textural development and performance were investigated by various analyses. The results indicate that: (1) Pyrite (FeS2) can transform into magnetite (Fe3O4) and hematite (Fe2O3) during CO2 and steam co-activation. Pyrite declines the graphitization degree and enhances the increment of AC’s C=O, COO, and π–π* content. Pyrite favors the increase of AC’s micropore porosity. High SBET and Smic of 1587 m2/g and 949 m2/g of AC-1FeS2 were achieved, which is higher by 13.5% and 83.6% than AC of 1398 m2/g and 517 m2/g, respectively. (2) The CO2 adsorption capacity of AC-1FeS2 is up to 2.06 mmol/g at 25 °C and 1.0 bar, which is higher by 11.3% than 1.85 mmol/g of AC. The enhancement of micropore by pyrite is the main aspect of improving CO2 capture. (3) AC-1FeS2 presents maximum MB adsorption capacity, reaching 63.3 mg/g, which is higher by 19.3% than 53.3 mg/g of AC. A serious of kinetics models was studied and the MB adsorption process could be better reflected by Pseudo second-order kinetics (R2=0.9538). The enhanced pore-filling, π–π* stacking and C=O complexation are one aspect of improving MB removal. In addition, the effect of Fe-O bonds or magnetic particles including Fe3O4 also enhances MB removal. The results of this investigation could provide new avenues and theoretical support for cost-effective AC with highly microporous production by utilizing high-iron-sulfur coal, to some extent, guide the actual industrial application.

The Utilization of Chicken Egg White Waste-Modified Nanofiber Membrane for Anionic Dye Removal in Batch and Flow Systems: Comprehensive Investigations into Equilibrium, Kinetics, and Breakthrough Curve.

This study investigated the use of chicken egg white (CEW) waste immobilized on weak acidic nanofiber membranes for removing the anionic acid orange 7 (AO7) dye in batch and continuous flow modes. Different experiments were conducted to evaluate the effectiveness of CEW-modified nanofiber membranes for AO7 removal, focusing on CEW immobilization conditions, adsorption kinetics, and thermodynamics. The CEW-modified nanofiber membrane (namely NM-COOH-CEW) exhibited a maximum AO7 adsorption capacity of 589.11 mg/g within approximately 30 min. The Freundlich isotherm model best represented the equilibrium adsorption data, while the adsorption kinetics followed a pseudo-second-order rate model. Breakthrough curve analysis using the Thomas model and the bed depth service time (BDST) model showed that the BDST model accurately described the curve, with an error percentage under 5%. To investigate AO7 elution efficiency, different concentrations of organic solvents or salts were tested as eluents. The NM-COOH-CEW nanofiber membrane exhibited promising performance as an effective adsorbent for removing AO7 dye from contaminated water.

High-pressure gas adsorption on activated carbons from pomegranate peels biochar: A promising approach for biogas purification

Biogas is a promising bioenergy source and its composition is based on methane (55–70% vol) but contains impurities such as CO2 (30–45% vol). Various technologies are available to purify biogas and produce biomethane that can be injected into the existing natural gas network. In this work, the effectiveness of activated carbons (ACs) obtained by chemical activation from industrial food waste for CO2 removal by adsorption was investigated. ACs with better textural development were obtained at higher activation temperature and dose of the activating agent (BET surface area and total pore volume up to 1446 m2/g and 0.589 cm3/g, respectively). The adsorbents exhibited a microporous character (micropore volume up to 0.472 cm3/g). The ACs were tested in high-pressure gas adsorption tests (CO2, CH4 and H2 up to 3, 8 and 4 MPa, respectively). All of them showed high, medium and low selectivity against for the adsorption of CO2, CH4 and H2, respectively, although with different efficiencies. The adsorbent obtained under the most aggressive activation conditions (900 °C, 1:1 wt ratio) showed the greatest textural development and the maximum adsorption capacity for CO2 (at 3 MPa) and CH4 (at 8 MPa) (495 mgCO2/g and 126 mgCH4/g). Despite the porosity of the materials, all showed a very low affinity for hydrogen adsorption at 4 MPa (up to 3.71 mgH2/g). Taking the above into account, these activated carbons could be used in the purification of biogas and in the separation of CO2/H2 mixtures to produce pure H2 and obtain hydrogen-free CO2 for capture and storage.

Synthesis of graphene oxide-choline chloride in order to remove phosphate ion from aqueous samples: study of mechanism, isotherm and adsorption kinetics

In this study, a graphene oxide-choline chloride adsorbent was used as a highly efficient and environmentally friendly material for removing phosphate ions from aqueous samples. Graphene oxide was synthesized using the Hummers method and then modified with choline chloride to create the graphene oxide-choline chloride adsorbent. The synthesized adsorbent was characterized using Fourier transform infrared spectrophotometry (FT-IR), Field Effect Scanning Electron Microscopy (FESEM), and Energy-dispersive X-ray spectroscopy (EDX). It was then applied to remove phosphate ions at different pH levels and stirring times. The results of this study showed that the maximum removal efficiency of phosphate ions was achieved at pH 5, with an adsorbent amount of 0.015 g and a stirring time of 30 minutes. Furthermore, it was observed that the adsorption of phosphate ions on the adsorbent surface followed the Langmuir isotherm (monolayer adsorption), with a maximum adsorption capacity of 217.4 mg/g. The examination of absorption kinetics also revealed that the absorption of phosphate ions followed pseudo-second-order kinetics, and an increase in temperature favored the progress of the reaction.

Magnetic solid phase adsorption of ceftiofur sodium in water by deep eutectic solvent modified banana peel‐MnFe2O4 biochar

AbstractMagnetic solid phase adsorption separation (MSPA) technology is an efficient and convenient separation method, which can simplify the separation step and shorten the separation time. It has wide application value in the purification of antibiotic pollutants in water. In this study, a novel magnetic biochar adsorbent (DES1@MnFe2O4‐BBC) with strong selectivity and high adsorption capacity was synthesized. It was composed of banana peel as the biochar source, Mn/Fe bimetallic oxide as the magnetic source and deep eutectic solvent (DES) as the functional monomer. The physicochemical properties of DES1@MnFe2O4‐BBC were systematically characterized by nitrogen adsorption–desorption, synchronous thermal analyzer, vibrating sample magnetometer, X‐ray diffractometer, X‐ray photoelectron spectroscopy, and field emission electron microscopy. The adsorption conditions were optimized by the single‐factor optimization method. Also, under the optimal adsorption conditions, the maximum adsorption capacity of DES1@MnFe2O4‐BBC for ceftiofur sodium was 75.01 mg·g−1. The test of adsorption thermodynamics and kinetics illustrated that the Langmuir isotherm adsorption model and pseudo‐second‐order kinetic equation were suitable well with the adsorption system established in this article. Adsorbent regeneration cycle experiment revealed that the DES1@MnFe2O4‐BBC was an efficient and reusable adsorbent. In the end, all research proves the novel magnetic adsorbent synthesized in this study can provide a new idea for the removal of antibiotics in water.

A highly efficient molecularly imprinted fluorescence sensor for selective and sensitive detection of tetracycline antibiotic residues in pork

Tetracyclines (TCs) residues in animal-based foods may cause consumer poisoning or allergic reactions, as well as resistance of pathogenic microorganisms. Therefore, a method to accurately monitor TCs is urgently needed. Here, a sensitive and greenificated molecularly imprinted fluorescent sensor (CDs@MIP) for detecting TCs residues using non-covalent imprinting binding method has been synthesized in a simple and safe manner. The sensor was demonstrated to contain specific adsorption sites and high adsorption capacity by static adsorption test results and Freundlich and Langmuir model analyses, and the maximum adsorption capacity was 45.8 mg/g. Moreover, the sensor exhibited intense blue-green fluorescence under UV light, and the fluorescence was gradually quenched as TCs was adsorbed to achieve the detection. The fluorescent spectrum experiment demonstrated that the prepared sensor has good recognition and detection performance for TCs with a linear range of 0.02–50 mg/L and a detection limit of 0.18 μg/L. Furthermore, This sensor is recyclable and can be used to determine TCs content in pork with a recovery rate of 98 %–108 %. Therefore, the constructed sensor provides a new convenient strategy for detecting TCs residues.

Simultaneous super-stable mineralization of Pb2+, Cd2+ and Cu2+ using MIL-101(Fe)@MgFe-LDH

The Pb2+, Cd2+ and Cu2+ co-existing pollution in battery and smelting industries have posed a significant threat to ecosystem and human health. Herein, we reported the fabrication of MIL-101(Fe)@MgFe-LDH successfully using in-situ nucleation and transformation strategy. The MIL-101(Fe)@MgFe-LDH exhibited maximum saturated adsorption capacities of 1408.57, 568.18 and 366.30 mg g−1 towards Pb2+, Cd2+ and Cu2+ in aqueous solution, respectively, and the adsorption data for each of these heavy metals can be well-fitted with pseudo-second-order kinetic and Langmuir isotherm models. Moreover, when MIL-101(Fe)@MgFe-LDH was applied for 300 mg kg−1 of Pb2+, Cd2+ and Cu2+ co-existing soil, the extremely low concentration of 1.24, 6.88 and 1.08 mg kg−1 for Pb2+, Cd2+ and Cu2+ can be reached in 7 days of column leaching experiment. Note that the release of Mg2+ from MIL-101(Fe)@MgFe-LDH was shown to promote pea seedling growth by acting as magnesium fertilizer. Detailed quasi-situ characterization and DFT calculation revealed the mechanism of isomorphic substitution of Mg2+ by Cu2+ accompanied by in-situ conversion to CuFe-LDH, while the formation of CdCO3 and Pb3(CO3)2(OH)2 can be demonstrated. Consequently, simultaneous super-stable mineralization of multiple heavy metals in water and soil can be accomplished.

High-efficiency removal of diclofenac sodium (DS) drug using chitosan-grafted-poly(acrylic acid-co-N-isopropylacrylamide)/kaolin clay hydrogel composite

ABSTRACT The current study mainly deals with the adsorptive removal of the diclofenac sodium (DS) drug from aqueous solution by the use of the kaolin-CS-g-poly(AA-co-NIPAM) composite. The synthesised composite was characterised by Fourier Transform infrared (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Transmission electron microscopy (TEM), energy dispersive X-Ray spectroscopy (EDS), atomic force microscopy (AFM), swelling % ratio and point of zero charge ( p H PZC ). The pHpzc of the composite was determined to be 4. The maximum adsorption capacity of 18.51 mg/g observed at the optimised conditions, including 0.1 g of kaolin clay dose, at neutral pH using composite dose of 0.06 g for 90 min. The optimum drug concentration was 500 mg/l for temperature of 30°C. Effect of the ionic strength on the adsorption capacity of the composite and its mechanism for DS drug removal has also been investigated. The process of drug adsorption on the prepared composite was chemical and data fits well to the pseudo second order and Langmuir model. Overall, the process was spontaneous and endothermic in nature.

A recyclable and durable magnetic cobalt nanoparticle-embedded mesoporous graphene nanohybrid for removal of pollutants from aqueous media

Cobalt nanoparticles (Co NPs) embedded in mesoporous graphene (MG) were prepared via a hydrothermal reaction followed by carbothermal reduction in an argon atmosphere. This cobalt nanoparticle-embedded mesoporous graphene (CoMG) was systematically investigated for structural, morphological, and magnetic properties before and after 10 successive cycles of adsorption and regeneration, using methylene blue (MB) dye as a model pollutant. The CoMG nanohybrid has a superior specific surface area of 807 m2 g−1, with a significant mesopore volume of 1.63 cm3 g−1 that allows fast and high pollutant removal efficiency of ∼84 % within 30 min as well as the maximum adsorption capacity of 178.6 mg g−1 with MB solution of 100 mg L−1, which is well described with pseudo-second-order adsorption kinetics. The consecutive adsorption−regeneration experiments revealed that the CoMG nanohybrid retained more than half of the initial dye removal efficiency even after being reused 10 times. After the tenth cycle, the regenerated CoMG maintained a high specific area of 688 m2 g−1 and a large mesopore volume of 1.51 cm3 g−1, indicating the long-lasting porous structure of the CoMG nanohybrid. The metallic cobalt phase and ferromagnetic nature of the Co NPs in the nanohybrid are retained because of the host MG, which prevents nanoparticle aggregation and serves as a protective environment for the embedded Co NPs in aqueous media during the adsorption−regeneration cycle tests of the adsorbent. The experimental results demonstrate that the CoMG nanohybrid has superior pollutant removal capacity and maintains more than half of the initial efficiency even after 10 cycles of use, making it a cost-efficient and energy-saving material for the removal of organic pollutants from aqueous media and in other environmental applications.

Carbon foams for CO2 adsorption: Synthesis, characterization and application

Carbon foams from phenolic resins of the resol and novolac type were synthesized and characterized, based on different experimental parameters and characterization techniques; with the objective of studying the synthesis process of carbon foams, their physicochemical characteristics, their CO2 adsorption capacities, and the influence that the different parameters applied in the synthesis process may have on the characteristics and adsorption capacity of each foam. The parameters applied in the synthesis of the carbon foams included the use of three different catalysts (sodium hydroxide, ammonia and oxalic acid), two foaming agents (n – pentane and dichloromethane) and two carbonization temperatures (600 and 800 °C).); and the characterization techniques used were CO2 adsorption isotherms, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy with X-ray scattering spectroscopy (SEM). – EDS). It is obtained that the highest adsorption capacities were obtained using sodium hydroxide as catalyst, and a carbonization temperature of 600 °C, this is reflected in the theoretical model of adsorption isotherms being the one that best describes the process of CO2 adsorption from carbon foams the Tóth model; with a maximum adsorption capacity (Qmax) higher than 50 cm3/g, up to 103 cm3/g.

Preparation of carboxyl-functionalized silica core-shell microspheres and their applications in weak cation exchange chromatography, heavy metal removal, and lysozyme enrichment.

Chromatography is a technique of separation based on adsorption and/or interaction of target molecules with stationary phases. Herein, we report the design and fabrication of BTDA@SiO2 core-shell microspheres as a new class of stationary phase and demonstrate its impressive performance for chromatographic separations. The silica microspheres of BTDA@SiO2 were synthesized by in situ method with 1,3,5-benzenetricarboxaldehyde and 3,5-diaminobenzoic to separate peptides and proteins on high-performance liquid chromatography. The BTDA@SiO2 core-shell structure has a high specific surface area and retention factor of 4.27 and 8.31 for anionic and cationic peptides, respectively. The separation factor and resolution were high as well. A typical chromatogram illustrated nearly baseline resolution of the two peptides in less than 3 min. The BTDA@SiO2 was also highly stable in the pH range of 1 to 14. Furthermore, the prepared BTDA@SiO2 core-shell material not only be used for chromatographic separation but also as heavy metal removal from water. Using a BTDA@SiO2, we also achieved a lysozyme enrichment with a maximum saturated adsorption capacity reaching 714mg/g. In summary, BTDA@SiO2 has great application prospects and significance in separation and purification systems.

Removal of arsenic (V) from water using arsenic-imprinted nanoparticles

ABSTRACT The aim of this study is the synthesis of nanoparticles with selective arsenic recognition capability for the removal of arsenic from water. Arsenic recognition based molecularly imprinted (As(V)-MIP) were synthesized using the molecular imprinting technique via mini-emulsion polymerization. The synthesized As(V)-MIP nanoparticles were characterized using zeta sizer, zeta potential, FTIR, Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and elemental analysis. The adsorption behavior of nanoparticles was investigated in a batch system at pH 4.0–9.0. The maximum adsorption capacity of As(V)-MIP nanoparticles was determined to be 54.29 mg As/g polymer at pH 5.0. Various parameters such as pH, concentration and adsorption time were examined to determine the optimum adsorption conditions. As(V)-MIP nanoparticle selectivity experiments were conducted in the presence of NO3 −, PO4 3−, and SO4 2− anions to determine the relative selectivity coefficients (K’). The experimental data showed a good correlation with the Langmuir isotherm equation and adherence of the adsorption process to pseudo-second-order kinetics was observed. Applying As(V)-MIP nanoparticles to real water sample showed up to 95.3% As(V) removal efficiency. Reusability experiments were performed by renewal of nanoparticles using a 1 M HNO3 solution containing 0.05% thiourea.

Assessment of activated carbon/alginate for the concurrent removal efficiency of paracetamol and caffeine from wastewater in their binary solutions

The increasing amount of pharmaceutical chemicals in wastewater is a concern for both public health and the environment. This research investigates the effectiveness of a new composite material made of alginate-activated carbon in removing caffeine and paracetamol from wastewater simultaneously. The composite material, produced using a simple technique, demonstrates excellent removal rates and exceptional adsorption properties for both medicinal chemicals. The structural stability and integrity of the composite are confirmed through comprehensive characterization methods including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, energy dispersive X-ray (EDX), and BET surface area analysis. The study uses batch adsorption experiments to assess the impact of various factors, such as pH, initial concentration, and contact time, on the efficiency of caffeine and paracetamol removal. The highest values for the adsorption process were 89.63% for Paracetamol and 97.32% for Caffeine, achieved under optimal experimental conditions (pH 7, 0.1 g dose of adsorbent at elevated temperature). Additionally, Kinetic studies and thermodynamic parameters such as ΔS°, ΔGº, and ΔH° were calculated, indicating that the adsorption process was endothermic and spontaneous for paracetamol, and exothermic and non-spontaneous for caffeine. Seven non-linear equilibrium isotherm models were utilized to fit the experimental data for paracetamol and caffeine at pH 7 showing maximum adsorption capacities (qmax) of 606.80 and 725.05 mg/g for Paracetamol and Caffeine, respectively with a high regression coefficient (R2) of 0.99 using alginate-activated carbon as an adsorbent, The results demonstrate the potential of alginate-activated carbon as an effective adsorbent for the simultaneous removal of various pharmaceutical pollutants, highlighting the synergistic adsorption effects of the composite material. The study also examines the safety of the composite material, particularly in the context of potential medical applications. The study emphasizes the potential for sustainable and repeated use of the activated carbon/alginate composite, demonstrating that it maintains both its structural integrity and adsorption effectiveness after multiple cycles of use. This study evaluated the suitability of the suggested analytical method using BAGI, a metric with a unique formula. The BAGI is a complementary tool to GAPI, Complex GAPI, AGREE, AGREE prep, and ESA. A major focus is on the practical elements of white analytical chemistry centered around "blue”.

Efficient adsorptive removal of 2,4-dichlorophenoxyacetic acid (2,4-D) using biomass derived magnetic activated carbon nanocomposite in synthetic and simulated agricultural runoff water

This study focused on evaluating the efficacy of a magnetic activated carbon material (CPAC@Fe3O4) derived from pods of copper pod tree in adsorbing the toxic herbicide, 2,4- (2,4-D) from aqueous solutions. The synthesized CPAC@Fe3O4 adsorbent, underwent various characterization techniques. FESEM images indicated a rough surface, incorporating iron oxide nanoparticles, while EDS analysis confirmed the presence of elements like Fe, O, and C. Notably, the CPAC@Fe3O4 exhibited high surface area (749.10 m2/g) and pore volume (0.5351 cm³/g), confirming its mesoporous nature. XRD investigations identified distinct signals associated with graphitic carbon and magnetite nanoparticles, while VSM analysis verified its magnetic properties with a high magnetic saturation value (2.72 emu/g). The adsorption process was exothermic, with a decrease in adsorption capacity at higher temperatures. Freundlich isotherm provided the best fit for the adsorption, and the pseudo-second-order equation effectively described the kinetics. Remarkably, the maximum adsorption capacity ranged from 246.43 to 261.03 mg/g, surpassing previously reported values. The ΔH° value (−8.67 kJ/mol) suggested a physisorption mechanism, and the negative ΔG° values established the spontaneous nature. Furthermore, the synthesized adsorbent demonstrated exceptional reusability, allowing for up to five cycles of adsorption-desorption operations. When applied to simulated agricultural runoff, CPAC@Fe3O4 showcased a significant adsorption capacity of 160.71 mg/g for 50 mg/L 2,4-D, using a 0.2 g/L dosage at pH 2. This study showcased the transformation of copper pod biomass into a valuable magnetic nanoadsorbent capable of efficiently eliminating the noxious 2,4-D pollutant from aqueous environments.