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In this work, adsorption and diffusion of CO2 on the Cu (111) surface, and Cu (111) surface modified by tungsten (W) and platinum (Pt) were studied and their electronic properties were examined using Density-functional theory (DFT) simulations. To specify the most favourable adsorption sites, the adsorption energies and distances of CO2 on various surface sites including on top, hexagonal closepacked (HCP), and bridge were calculated. The crystal orbital overlap population analysis was employed to investigate the properties and characteristics of chemical bonding. The computed Bader atomic charges of CO2 molecules on different catalyst surfaces indicated that the Cu-W alloy surface had a higher net charge transfer than other surfaces. This result suggests that the adsorption of CO2 on the Cu-W alloy surface is more powerful than on other surfaces. The outcomes indicated that the CO2 adsorption on the surfaces follows the order of Cu-W alloy > Cu-Pt alloy > Cu. Also, the diffusion on the alloy surfaces was faster than on the Cu surface, which confirms the adsorption energy. [ABSTRACT FROM AUTHOR]

Fluoride (F–) is one of the common water pollutants, which causes severe diseases if be present over 1.5 mg/L suggested by WHO for drinking water. There is essential to find a simple and cost-effective method for excess F– removal from contaminated water. In this study, municipal solid waste compost ash (MSWCA) was used to remove F– from aqueous solution. The effect of operational variables such as adsorbent calcination temperature (550–900°C), adsorbent dose (0.25–1.5 g/L), pH (2–12), occurrence of competing anions (HCO3−, CO32−, Cl−, NO3− and SO42−), adsorption temperature (20–50°C) and mixing time (15–120 min) were investigated. F–adsorption was highest when compost ash calcinated at 550°C. F– removal increased from 42.6 to 87.7% by increasing adsorbent dose from 0.25 to 1.5 g/L. The removal also increased 4.4% when the temperature of solutions increased from 20 to 50°C, an indicative of endothermic process. Furthermore, adsorption increased by increasing pH from 4 to 10 and then decreased with pH up to 12. F− removal reduced about 10% in the presence of SO42−. Based on pseudo- second-order kinetic model, it was found that the process was controlled by chemisorption. The equilibrium data were well fitted with Langmuir model, which implied the F−ions doesn't interact and adsorbed in monolayer onto MSWA. The Langmuir maximum adsorption capacity was 30.56 mg F/g MSWCA. Due to excellent adsorptive properties, MSWCA presents as a promising material for F− adsorption from wastewaters or landfill leachates. [ABSTRACT FROM AUTHOR]

Nickel ferrite nanoparticles prepared by a microwave-assisted autocombustion method with different fuels and microwave powers were used as bare adsorbents for 2-nitrophenol removal from aqueous solutions. Characterization of the as-prepared samples revealed a fundamental variety with respect to their size and surface area. Meanwhile, the crystal phase, functional groups, surface polarity, and magnetic properties remained almost the same. After electing the most efficient adsorbent based on batch experiments, pH influence was established and optimized. Afterward, equilibrium studies were conducted. The kinetic models and adsorption isotherms further facilitated a better understanding of the adsorption mechanism that comprised mainly the multilayered condensation of 2-nitrophenol molecules through the hydrogen bonding. [ABSTRACT FROM AUTHOR]

Fluoride concentration, if exceeds the standard levels in drinking water, can lead to adverse effects on human health. Adsorption is one of the widely considered appropriate technologies for water defluoridation. In this study, modified pumice with HCl and NaOH were used for the fluoride removal from aqueous solution, and two linear forms of the Langmuir and Freundlich isotherms model were applied to determine the best fit of equilibrium expressions. Several experimental parameters including pH (2–10), temperature (20–60°C), adsorbent dosage (2–10 g/L), fluoride concentration (5–20 mg/L), and contact time were studied. Results showed that removal efficiency improved with increase in contact time, initial fluoride concentration, and adsorbent dosage. The maximum removal efficiency (96%) was observed at pH 6, 10 g/L adsorbent dosage, 20°C solution temperature, 90-min reaction time, and 20 mg/L of fluoride concentration. The kinetic studies indicated that the adsorption equilibrium and kinetic data were in good agreement with the Langmuir Model (R2 = 0.95) with qmax = 65.5 mg/g and pseudo-second-order reaction (R2 = 0.99). According to the results, the modified pumice was found to be able to remove fluoride from aqueous environments with good removal efficiency and adsorption capacity. [ABSTRACT FROM AUTHOR]

Granular ferric hydroxide was used in the present study to evaluate the efficiency of phosphate removal from aqueous solutions using central composite design and optimization by response surface methodology (RSM). The interaction of important parameters including pH, contact time, adsorbent dose and initial concentration of phosphate was used on the phosphate removal process and optimization of the removal process. The design of this research was based on central composite, which is one of the methods of RSM. The number of standard samples in this study was 35. The results of optimization of the variables derived by solver command in the initial phosphate concentration were 1.78 mg L-1, pH = 5.81, contact time = 82 min, and adsorbent dosage = 4.03 g, maximum removal efficiency of 92.14%. Experimental results of phosphate removal with three repetitions indicated that maximum removal efficiency of phosphate in optimal conditions was 91.6%. Also, the experimental adsorption data indicated that the data follow the pseudo-second-order kinetic model (R² = 0.979) and Freundlich isotherm model (R² = 0.997). Based on the Langmuir model, the maximum phosphate adsorption (Qmax) was 6.541 mg g-1. In general, it can be concluded that granular ferric hydroxide with a good quality and low operating cost has high efficiency in removal of phosphate from various aqueous solutions. [ABSTRACT FROM AUTHOR]

An effort has been made in the present research to evaluate the agro-based adsorbents such as coconut shell, walnut shell, and almond shell for the removal of cadmium from electroplating industrial effluent. Adsorption experiments were conducted to evaluate the performance. The highest removal efficiency for Cd(II) is 83.7% at pH 6.5 for coconut shell-activated carbon. The percentage removal of cadmium increases with the decrease in metal concentration. The extent of removal depends on the metal ion concentration, adsorbent dose, contact time, and particle size. Coconut shell is found to be more effective with respect to removal efficiency. Cadmium adsorption follows second-order rate equation for coconut shell. The isotherm data obtained more closely follow the Freundilch adsorption isotherm for coconut shell, while walnut shell and almond shell follow the Langmuir adsorption isotherm better. The coconut shell has the highest potential to remove cadmium ion from electroplating wastewater. [ABSTRACT FROM AUTHOR]

Having unique properties, metal–organic frameworks are recognized as interesting materials for many applications. Leaf-shaped zeolitic imidazolate framework-8 (L-ZIF-8) with a 16.66 m²/g Brunauer- Emmett-Teller (BET) surface area and total pore volume of 0.0572 cm³/g was synthesized in aqueous medium and room temperature. L-ZIF-8 then used for P removal from aqueous solutions and a polynomial prediction model for phosphate (P) removal was developed by designing the experiments using central composite design. The model terms showed an increase in P removal with adsorbent dosage and contact time and also by decreasing pH. The highest P removal after model optimization determined to be at pH 4, L-ZIF-8 dosage 0.6 g/L, and 84 min contact time. The isotherm models indicated a monolayer adsorption of P onto L-ZIF-8 with a maximum 51.24 mg P/g of adsorbent. Study of P removal dynamic revealed that the process controlled by chemisorption. [ABSTRACT FROM AUTHOR]

A new nanostructure Cu(II) ion-imprinted polymer (IIP) has been prepared using 1-(2-pyridylazo)-2-naphthol as a ligand. The Cu(II)–PAN complex was synthesized and polymerized in the presence of 2-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker) and 2,2′-azobisisobutyronitrile (the initiator) via precipitation polymerization using trapping method. The prepared IIP was characterized by FTIR spectroscopy, scanning electron microscopy, and transmission electron microscopy. The optimal pH value for the quantitative preconcentration was 6.0 and maximum sorbent capacity was 11.53 mg g−1. Under the optimized conditions, the method had a linear analytical range from 1 to 50 μg L−1. The detection limit, relative standard deviation, and recovery of the method were evaluated as 0.29 μg L−1, 3.6, and 94–97%, respectively. The developed method was successfully applied to the selective extraction and determination of trace amount of copper ions in water samples and some medicinal plants by inductively coupled plasma-optical emission spectrometry. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are a promising class of porous nanomaterials in the field of environmental remediation. Ni-MOF and Fe-MOF were chosen for their advantages such as structural robustness and ease of synthesis route. The structure of prepared MOFs was characterized using FE-SEM, XRD, FTIR, and N 2 adsorption-desorption. The efficiency of MOFs to remove organic model contaminants (anionic Alizarin Red S (ARS) and cationic malachite green (MG) and inorganic fluoride was studied. Fe-MOF and Ni-MOF adsorbed 67, 88, 6% and 32, 5, and 9% of fluoride, ARS, and MG, respectively. Further study on ARS adsorption by Fe-MOF showed that the removal efficiency was high in a wide range of pH from 3 to 9. Moreover, dye removal was directly increased by adsorbent mass (0.1–0.75 g/L) and decreased by ARS concentration (25–100 mg/L). The pseudo-first-order kinetic model and Langmuir isotherm model with a q max of 176.68 mg/g described the experimental data well. The separation factor, K L, was in the range of 0–1, which means the adsorption process was favorable. In conclusion, Fe-MOF showed remarkable adsorption of organic and inorganic model contaminants. • Ni-MOF and Fe-MOF have structural robustness and ease of synthesis route. • The efficiency of MOFs to remove ARS, MG and inorganic fluoride was studied. • The pseudo-first-order and Langmuir isotherm model described the experimental data well. • The structural integrity of Ni-MOF and Fe-MOF, and challenges are provided. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNT) were used to separate amoxicillin from aqueous media. The parameters affecting amoxicillin adsorption such as pH, temperature, time, interferences of similar molecules, and the amount of adsorbent used were studied. Amoxicillin adsorption using MWCNT was compared to that using Fullerene C60 and activated carbon (AC). The adsorption efficiency of 0.1 and 0.2 g of MWCNT using in a continuous mode were 86.5% and 87.9%, respectively. Evaluation of the adsorbent capacity showed that each gram of MWCNT can absorb 22.9 mg amoxicillin. The effect of pH was studied over the range 2–8 and revealed that adsorption of the amoxicillin at the initial pH of 4.6 was more effective than any other pH. The adsorption of amoxicillin on MWCNT was much greater than Fullerene C60 and AC. Adsorption data showed that they were best fitted to the Langmuir isotherm. [ABSTRACT FROM PUBLISHER]

This inquiry focuses on acquiring empirical models to predict ciprofloxacin removal using magnetization of functionalized multi-walled carbon nanotubes (FMWCNTs-Fe 3 O 4) from an aqueous solution. The response surface methodology (RSM) and support vector regression (SVR) as data mining techniques were adopted to develop models. Critical parameter effects comprising pH (3−10), adsorbent dose (0.2–1 g/L), contact time (5–60 min) and ciprofloxacin concentrations (30–100 mg/L) were analysed. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isothermal models were utilized to fit the empirical data. FMWCNTs-Fe 3 O 4 prepared by chemical co-precipitation method was loaded by Fe 3 O 4 nanoparticles (using sonication) to synthesize functionalized multi-walled carbon nanotubes to remove ciprofloxacin (CIP). FMWCNTs-Fe 3 O 4 were characterized by fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) methods. The Langmuir model was utilized to precisely describe the maximum adsorption capacity(q max) of 107.66 mg/g with R2 = 0.998. In this study, the pseudo-second-order model exactly described the adsorption process(R2 = 0.99). The results illustrated that the LSSVM (least squares support vector machine) model efficiently predicted the CIP removal percentage with very high accuracy in the training phase (R2 = 0.975) and the test phase (R2 =0.970). Moreover, the highest removal percentages in optimized step were achieved for RSM (pH 5.4, dose 0.78 g/L, time of 24.5 min, and CIP concentrations of 59 mg/L) and GA (genetic algorithm) (pH 4.4, dose 0.74 g/L, time of 42 min, and CIP concentrations of 38 mg/L) techniques by 88% and 99.1%, respectively. The FMCNTs-Fe 3 O 4 efficiency has decreased by 12% even after five used cycles relative to the optimal conditions (regeneration). Therefore, FMWCNTs-Fe 3 O 4 adsorption was considered to be an effective technique for CIP removal in the aqueous environment. [Display omitted] • RSM and LSSVM modeling to efficiency in adsorption of CIP from aqueous solutions using FMWCNTs-Fe 3 O 4. • The CIP removal percentage were accurately predicted by LSSWM model. • The Langmuir model was utilized to precisely describe the q max of 107.66 mg/g with R2 = 0.998. • The removal percentages in the optimized step were achieved for RSM and GA techniques by 88% and 99.1%. • RSM and GA techniques' highest removal percentage in the optimized step 88% and 99.1% were obtained. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are currently recognized as unique platforms for environmental studies. This study evaluated the potential of nine MOFs from ZIF-8, ZIF-67, and UIO-66 families for the removal of ciprofloxacin (CIP), a toxic, bio-accumulative, and persistent fluoroquinolone antibiotic. ZIF-67-SO4, with a rhombic crystalline morphology and 1375 m2/g BET surface area, has the highest CIP adsorption efficiency among the studied MOFs. The mathematical sorption model predicted that the highest CIP removal (99.2%) occurs when adsorbent dose, pH, and agitation time are adjusted to 6.82, 832.4 mg/L, and 39.95 min, respectively. Further studies revealed that the CIP adsorbed onto ZIF-67-SO4 in monolayer (qmax: 2537.5 mg/g) and chemisorption controlled the rate of the process. Mass transfer kinetic coefficients improved significantly by sonication at 35 KHz in comparison with mechanical agitation. Thermodynamic parameters (minus signs of ∆G° [7.8 to 14.2], positive signs of ∆H° (58.9 KJ/mol), and ∆S° (0.23 KJ/mol·K)) demonstrated the spontaneous, endothermic, and chemical sorption of CIP. The level of cobalt leached from ZIF-67-SO4 structure varied 1.2–4.5 mg/L, depending on pH, mixing time, and agitation type. In conclusion, the excellent adsorption properties of ZIF-67-SO4 for CIP, made it an outstanding candidate for environmental protection purposes. [ABSTRACT FROM AUTHOR]

In the present study, metal organic frameworks (MOFs) and aminated graphitic carbonaceous structure (ACS-RGO) through chemical synthesis prepared by a simple precipitation method and used for diazinon removal. Several techniques such as XRD , FESEM and FTIR were applied for identification of MOF-5 and ACS-RGO. Also, response surface methodology (RSM) was employed in this work to look at the effectiveness of diazinon adsorption. To forecast pesticide removal, we applied artificial neural network (ANN) and Box-Behnken Design (BBD) models. For the ANN model, a sensitivity analysis was also performed. The effect of independent variables like solution pH, various concentrations of diazinon, MOFs and ACS-RGO adsorbent dose and contact time were assessed to find out the optimum conditions. Based on the model prediction, the optimal condition for adsorption ACS-RGO and MOF-5 were determined to be pH 6.6 and 6.6, adsorbent dose of 0.59 and 0.906 g/L, and mixing time of 52.15 and 36.96 min respectively. These conditions resulted in 96.69% and 80.62% diazinon removal using ACS-RGO and MOF-5, respectively. Isotherm studies proved the adsorption of ACS-RGO and MOF-5 following the Langmuir isotherm model for diazinon removal. Diazinon removal followed by the pseudo-second and Pseudo-first order kinetics model provides a better fit for analyzing the kinetic data associated with pesticide adsorption for ACS-RGO and MOF-5, respectively. Based on the obtained results, the predicted values for the efficiency of diazinon removal with the ANN and BBD were similar (R2=0.98). Therefore, two models were able to predict diazinon removal by ACS-RGO and MOF-5. [Display omitted] • MOF-5 and ACS-RGO were synthesized and applied for diazinon removal. • A comparison was made between the ANN and BBD models for diazinon removal prediction. • At optimal conditions, the diazinon removal for ACS-RGO and MOF-5 were 96.69% and 80.62%, respectively. [ABSTRACT FROM AUTHOR]

In modern times, wastewater treatment is vital due to increased water contamination arising from pollutants such as nutrients, pathogens, heavy metals, and pharmaceutical residues. Polysaccharides (PSAs) are natural, renewable, and non-toxic biopolymers used in wastewater treatment in the field of gas separation, liquid filtration, adsorption processes, pervaporation, and proton exchange membranes. Since addition of nanoparticles to PSAs improves their sustainability and strength, nanocomposite PSAs has gained significant attention for wastewater treatment in the past decade. This review presents a comprehensive analysis of PSA-based nanocomposites used for efficient wastewater treatment, focusing on adsorption, photocatalysis, and membrane-based methods. It also discusses potential future applications, challenges, and opportunities in adsorption, filtration, and photocatalysis. Recently, PSAs have shown promise as adsorbents in biological-based systems, effectively removing heavy metals that could hinder microbial activity. Cellulose-mediated adsorbents have successfully removed various pollutants from wastewater, including heavy metals, dyes, oil, organic solvents, pesticides, and pharmaceutical residues. Thus, PSA nanocomposites would support biological processes in wastewater treatment plants. A major concern is the discharge of antibiotic wastes from pharmaceutical industries, posing significant environmental and health risks. PSA-mediated bio-adsorbents, like clay polymeric nanocomposite hydrogel beads, efficiently remove antibiotics from wastewater, ensuring water quality and ecosystem balance. The successful use of PSA-mediated bio-adsorbents in wastewater treatment depends on ongoing research to optimize their application and evaluate their potential environmental impacts. Implementing these eco-friendly adsorbents on a large scale holds great promise in significantly reducing water pollution, safeguarding ecosystems, and protecting human health. [Display omitted] • Polysaccharides (PSA) are eco-friendly biopolymers in wastewater treatment. • Analyzed gas and liquid filtration, adsorption and proton exchange membranes. • PSA nanocomposites aid in biological processes like antibiotic waste removal from water. • Transitioning from lab to large-scale PSA use in wastewater treatment is pivotal. [ABSTRACT FROM AUTHOR]

Arsenic is the hazardous species and still is the global challenge in water treatment. Apatite soil is highly rich in arsenic species, and its mining presents various environmental issues. In this study, novel magnetic microbeads as adsorbent were developed for the elimination of hazardous arsenic ions from apatite soil's aqueous leachate before discharging into environment. The microbeads were fabricated with metformin polyether sulfone after being doped with zero-valent iron (Met-PES/ZVI). The microbeads were characterized using various techniques, including FTIR, XRD, SEM-EDX, VSM, and zeta potential analysis. The developed adsorbent demonstrated a significant elimination in arsenic in aqueous leachate, achieving 82.39% removal after 30 min of contact time, which further increased to 90% after 180 min of shaking. The kinetic analysis revealed that the pseudo-second-order model best represented the adsorption process. The intra-particle diffusion model indicated that the adsorption occurred in two steps. The Langmuir model (R2 = 0.991), with a maximum adsorption capacity of 188.679 mg g−1, was discovered to be the best fit for the experimental data as compared Freundlich model (R2 = 0.981). According to the thermodynamic outcome (ΔG < −20 kJ/mol), the adsorption process was spontaneous and involved physisorption. These findings demonstrate the potential of magnetic Met-PES/ZVI microbeads as an efficient adsorbent for the removal of arsenic from apatite soil aqueous leachate. • The novel magnetic microbeads were developed based on metformin polyether sulfone doped with zero-valent iron. • Magnetic microbeads (Met-PES/ZVI) used for the removal of hazardous arsenic ions from apatite soil aqueous leachate. • Significant reduction in arsenic in aqueous leachate, achieving 82.39% removal after 30 min. • Langmuir model was fit for the experimental data, with a maximum adsorption capacity of 188.679 mg g−1. • Thermodynamic analysis showed that the adsorption process was spontaneous and involved physisorption. [ABSTRACT FROM AUTHOR]

Nanodiamonds (NDs) are zero-dimensional (0D) carbon-based nanoparticles with SP3/SP2-hybridized carbon atoms that have shown great potential in wastewater treatment areas due to their high surface area, chemical stability, and unique adsorption properties. They can efficiently remove a wide range of pollutants from water, including heavy metals, organic compounds, and dyes via various mechanisms such as electrostatic interactions, π-π stacking, and ion exchange. NDs can be functionalized following different surface chemistries, enabling tailored surface properties and enhanced pollutant adsorption capabilities. This review covers recent research on the application of nanodiamonds in wastewater treatment domain with a major emphasis on adsorption, photocatalytic degradation, and membrane separation, highlighting their promising performances, challenges, and future directions. • Nanodiamonds can be tailored with different surface properties. • Functionalization and modification of ND offer tailored surface properties and enhance wastewater treatment. • Surface modification of NDs enhances their interaction with water pollutants. • Combination of NDs with other materials enhance their efficiency in wastewater treatment. • NDs show promising performance in adsorption, photocatalysis and membrane separation. [ABSTRACT FROM AUTHOR]