Removal Efficiency Of Ions Research Articles

Optimisation of phytoremediation of zinc ion by Lemnaceae using response surface methodology

Phytoremediation, an eco-friendly approach, offers a green pathway towards cleaner and safer water resources. The efficiency of zinc ion removal through phytoremediation by Lemnaceae as a function of Lemnaceae species, the mass of duckweed and the initial zinc ion concentration was studied. The central composite design was applied for surface response modelling to analyse the effects of the combination of environmental factors and optimise the phytoremediation process. The model achieved a satisfactory prediction with a coefficient of determination (R2) of 0.985 based on a modified quadratic model for the optimised phytoremediation process. Furthermore, the analysis of variance (ANOVA) was conducted to assess the adequacy and significance of the generated model. The optimal zinc ion removal of 88 % could be achieved by Spirodela polyrhiza, Wolffia arrhiza and Lemna minor at the initial zinc ion concentration of 92.92 mg/L, 39.5 mg/L, and 21.08 mg/L and duckweed mass of 22.56 g, 22.38 g, and 24.81 g under the exposure of ambient conditions with sufficient daylight exposure.

Nickel removal from synthetic wastewater by novel zeolite-doped magnesium- iron- and zinc-oxide nanocomposites by hydrothermal-calcination technique

This study aims to modify raw zeolite with metal oxide nanocomposites to remove nickel (Ni) ions from synthetic wastewater. Novel zeolite-doped magnesium oxide (MgO), iron oxide (Fe3O4), and zinc oxide (ZnO) nanocomposites were synthesized by hydrothermal-calcination methods. The novel zeolite-doped metal oxide nanocomposites were used as adsorbents to remove Ni (II) ions from synthetic wastewater. Several advanced techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM) were applied to study the structural, morphological, chemical, and magnetic properties of the prepared materials. Doped zeolite with ZnO, MgO, and Fe3O4 significantly enhances the removal of Ni (II) ions from synthetic wastewater. The zeolite-doped MgO + Fe3O4 + ZnO sample achieved a Ni (II) ions removal efficiency of 99.6%, compared to 58.9% for raw zeolites. The removal efficiencies of Ni (II) ions (Ci = 30 mg/L) from highest to lowest were 99.56%, 99.53%, 91.4%, 67.8%, and 58.93% by zeolite-doped MgO + Fe3O4 + ZnO, zeolite-doped MgO, zeolite-doped ZnO, zeolite-doped Fe3O4, and raw zeolite sample, respectively. The highest adsorption capacity was 17.13 mg/g of zeolite-doped MgO + Fe3O4 + ZnO samples. The experimental adsorption data collected were fitted using five isotherm models, and four kinetic models. The Langmuir adsorption isotherm model and the pseudo-second-order kinetic model provided the best fit for the experimental adsorption data. This suggests that the adsorption process is complex, possibly involving electron interactions between the active sites of doped zeolite and Ni (II) species. The obtained data indicates that zeolite-doped with MgO, Fe3O4, and ZnO notably enhances the adsorptive properties of Ni (II) from synthetic wastewater. The obtained thermodynamic values confirmed that the adsorption process is spontaneous and endothermic, with increased randomness at the solid-solution interface during the adsorption process.

Layered graphene oxide membrane for heavy metal separation via molecular dynamics simulation

Purification of water and industrial wastewater, especially those containing toxic metals, is a critical challenge for developing societies. Nano membranes, including two-dimensional graphene oxide nanomaterials, have recently gained prominence as an alternative to traditional polymer membranes. However, the efficacy of these membranes for the removal of heavy metals has not been extensively studied. In this work, molecular dynamics simulation is used to investigate the performance of graphene oxide membranes, with the oxidation ratio of 20 %, for the removal of mercury and arsenic ions at a concentration of 0.5 M, via reverse osmosis at 200 Mpa pressure. Results demonstrate that graphene oxide membranes are effective for separating heavy metal ions while maintaining good water flow. The mechanism of water molecule passage through the graphene oxide membrane is also investigated by analyzing the structural images of water molecules between the layers, water density diagrams in the nanochannel, and the number of hydrogen bonds at various channel inter-layer distances. In addition, raising the temperature of the aqueous solution from 300 to 340 K increases the water flux and decreases ion rejection. Increasing the concentration of mercury and arsenic ions from 0.5 to 1 M in the feed water leads to decrease in water flux with the least impact on ion rejection. Furthermore, the influence of membrane geometry on its performance is also investigated. By comparing the cross-flow and dead-end geometries, it is found that the cross-flow geometry performs better than the dead-end geometry both in water flux and the removal efficiency of mercury and arsenic ions. The potential of graphene oxide membranes in the treatment of wastewater containing heavy metals is highlighted by these findings, which provide insights into optimizing their design and operational parameters.

Comparative Study of Ammonium and Orthophosphate Removal Efficiency with Natural and Modified Clay-Based Materials, for Sustainable Management of Eutrophic Water Bodies

Eutrophication, a global threat that leads to degradation of freshwater and seawater aquatic ecosystems, is driven by excessive nutrient loading. This study explores the sustainable management of eutrophic water bodies with the application of natural and modified clay-based materials as a practical solution to mitigate eutrophication by removing ammonium and orthophosphate ions. Comparative analyses of six materials: natural zeolite, bentonite, and perlite, along with their modification with calcium and iron, were assessed after kinetic analysis of each material. Batch adsorption experiments were performed to evaluate the material’s performance in fresh and seawater. Fitting experimental data assessed adsorption kinetics to pseudo-second-order models. Furthermore, Langmuir isotherm models were employed to determine each material’s maximum adsorption capacity for ammonium and orthophosphate ion uptake. The results revealed that freshwater applications of modified zeolite or natural bentonite achieved better orthophosphate ion removal efficiency from seawater, whereas employing natural zeolite maximized the ammonium ion removal efficiency in freshwater bodies. Finally, orthophosphate and ammonium ion removal efficiency results for almost all materials were diminished in seawater. This research contributes valuable insights to the development of efficient and sustainable nutrient removal methodologies to remediate natural eutrophic water bodies and protect aquatic ecosystems.

The Effect of the Nano-Sized Plastic on Activated Carbon (AC) Electrode and Ion-Exchange Membrane (IEM) in Membrane Capacitive Deionization (MCDI)

The emerging water treatment technology, membrane capacitive deionization (MCDI), utilizes ion exchange membranes (IEM) and porous electrodes to adsorb ions from low-concentration brines or inorganic wastewater. Numerous studies about salt adsorption capacity (SAC) of MCDI have been conducted as it indicates the performance of desalination system. Former studies have shown that how various factors influence on the ion removal efficiency of MCDI, such as operating conditions (e.g., ion voltage, flow rate) and water quality parameters (e.g., natural organic matters, heavy metals). In recent years, micro-sized plastic particles (<5mm) and nano-sized plastic particles (1-1000nm) have become a serious problem that threatens water resources as plastic product consumption has increased. Especially, nano-sized plastics, due to their extremely small size, not only contaminates water resources but also can impair the water treatment system. Nano-sized plastics are expected to pass through the pores (100-200nm) of ion exchange membranes (IEMs) in MCDI, given their smaller size compared to the pores of IMEs. Consequently, the porous electrodes could be clogged, leading to a reduction in specific surface area. The reduction may occur due to the potential impact of nano-sized plastics on the pores (>50nm) of the electrodes, resulting in a decrease of the SAC of MCDI. This study investigated the effect of nano-sized plastic on the porous electrodes and the performance of MCDI. The potential impact of newly exposed nano-sized plastics on water electrochemical water treatment system will be introduced.

Magnetic nanoparticles for efficient heavy metal removal: synthesis, adsorption capacity, and key experimental parameters

Abstract Heavy metals are toxic, non-biodegradable pollutants that pose serious risks to human health and the environment, even at trace concentrations. The contamination of drinking water and groundwater by heavy metals requires urgent attention. Nanotechnology has advanced significantly over the past decade, offering innovative solutions for water purification, particularly through the adsorption of heavy metal ions using nanomaterials. This study focuses on the synthesis of magnetic nanoparticles, their adsorption capacity, and the desorption process. Additionally, the effects of key experimental parameters – such as contact time, ion concentration, pH, temperature, ionic strength, and adsorbent dose – on the removal efficiency of metal ions are examined. The findings underscore the potential of magnetic nanoparticles for effective heavy metal remediation in water.

Synergistic effect of rice husk-derived activated carbon modified by Ni/Al-layered double hydroxides for lead removal from industrial wastewater

To enhance the adsorption efficiency of activated carbon for heavy metals, herein we synthesized a novel composite adsorbent by loading of nickel/aluminum layered double hydroxides (Ni/Al-LDH) onto a chemically modified Egyptian rice husk-derived activated carbon. The characterization techniques used for determining the chemical and surface structure of the prepared composite were including FTIR, XRD, SEM, and BET which confirmed the successful loading of LDH onto the prepared activated carbon surface. The modified activated carbon established significantly upgraded performance in eliminating lead ions from wastewater. Adsorption studies revealed that the process follows Freundlich isotherm and pseudo-second-order kinetics, indicating chemisorption as the rate-determining step. The maximum lead ions removal (using 50 ppm concentration solution) was 82% after 210 min at pH 7. The improved lead ions removal efficiency was attributed to the synergistic effect of the activated carbon’s surface chemistry and the LDH’s ion exchange properties. The presence of chelating groups like hydroxyl (–OH), amide (–CO–NH–), carboxylate (–COOH), and nitrogen-containing functional groups on the activated carbon surface, along with the hydroxide groups of the LDH, facilitates the complexation and adsorption of lead ions.

Tactfully introducing amphoteric group into electroactive membrane motivates highly efficient H2O splitting for reversible removal and recovery of nickel(II)

Membrane-based electro-deposition (MED) is an original process promising for reversible removal and recovery of toxic heavy metal ions from wastewater. The removal efficiency of heavy metal ions, however, was limited by the poor membrane surface H2O splitting in the conventional ion exchange membrane (IEM). Inspired by the amphoteric interface-triggered ion exchange resin regeneration phenomenon in electro-deionization, herein we subtly introduced the amphoteric group into IEM as a proof of concept to solve the above bottleneck. By virtue of the “electronic porter” role of the amphoteric -3OS-R-N(CH3)3+, the electron extraction from adsorbed H2O could be accelerated, extending the H2O splitting from the conventional membrane surface to the bulk membrane interior. Such an H2O splitting extension favorably produced an intensified and well-modeled OH- production region at the anodic side of IEM, enhancing the Ni2+ basic deposition accordingly. This special characteristic allowed our MED to realize a super-eminent metal ion removal rate (10.5 mol·h−1·m−2) along with an ultra-low specific energy consumption (0.1 kWh·mol−1) for Ni2+ removal, which considerably surpassed those of state-of-the-art heavy metal ion removal processes reported yet. Further, the deposited Ni2+ could be in situ recovered in conjunction with the facile polarity reversal method. The amphoteric electroactive membrane with high H2O splitting activity is expected to pave the path to engineering MED for efficient heavy metal ion removal and recovery.

Walnut shell/phenolic resin carbon electrodes via laser sintering and KOH activation

Currently, the application of 3D-printed biomass-based carbon electrodes is hindered by their suboptimal performance. This study utilizes walnut shell powder as a carbon source and employs selective laser sintering technology for the efficient 3D printing of a double-helix carbon precursor. High-performance biomass-based carbon electrodes are prepared through carbonization and potassium hydroxide (KOH) activation. Comparative studies on the microstructure and electrochemical performance of the carbonized and activated samples were conducted. Experimental results demonstrate that potassium hydroxide activation significantly enhances the microstructure of the carbon electrodes, leading to marked improvements in their electrochemical performance. During desalination experiments, the carbon electrodes exhibited excellent ion removal efficiency, with a maximum conductivity reduction rate of 0.2 μS/cm·min, confirming their feasibility in seawater desalination applications. This research validates the potential of walnut shell biomass for the preparation of 3D-printed carbon electrodes, addressing bottlenecks in traditional carbon electrode manufacturing processes while promoting efficient biomass utilization and environmental protection.

Removal of Radioactive Co(II) and Sr(II) using (Co0.5Zn0.5)Fe2O4 Nanoparticles Co-doped with Barium and Antimony

Radioactive pollution poses significant environmental and health risks, including increased cancer rates, genetic mutations, and ecosystem damage, making the removal of radioactive ions from water crucial. Spinel ferrite nanoparticles are promising adsorbents for this purpose owing to their magnetic and adsorption properties. Herein, the novel synthesis of (Co0.5−xZn0.5−xBaxSbx)Fe2O4 nanoparticles (0 ≤ x ≤ 0.1) is reported as an effective solution for adsorbing radioactive Co(II) and Sr(II) ions. Co-doping with Ba and Sb enhances the structural stability, magnetic behavior, and adsorption efficiency of these nanoparticles. X-ray diffraction analysis confirmed sample purity with minimal hematite phase, while Fourier transform infrared spectroscopy verified the spinel structure. Transmission electron microscopy analysis revealed spherical morphology and indicated that increasing x from 0.00 to 0.10 reduced crystallite and grain sizes of nanoparticles from 11.28 to 6.49 nm and 24.47 to 10.88 nm, respectively. Energy-dispersive X-ray spectroscopy confirmed pure elemental compositions and the successful substitution of host ions with dopant ions in the nanoparticles, while X-ray photoelectron spectroscopy analysis provided insights into the chemical oxidation states. Vibrating sample magnetometer results indicated soft ferromagnetic behavior. In adsorption experiments, we examined contact time (0–180 min), pH (2–10), adsorbent dosage (0.04–0.10 g), initial ion concentration (10–250 mg.L−1), and temperature (293–313 K) to determine their effects on adsorption efficiency and optimize conditions for maximum contaminant removal. Nanoparticles with x = 0.06 exhibited the highest ion-removal efficiencies, achieving 88.3% for Co(II) and 96.3% for Sr(II) after contact time of 180 min, with maximum efficiencies observed at pH 8 for Co(II) and pH 6 for Sr(II). Co(II) adsorption followed the Freundlich isotherm, while Sr(II) adsorption adhered to the Temkin model. Kinetics for both ions conformed to the pseudo-second-order model, demonstrating the potential of Ba and Sb co-doped ferrite nanoparticles for efficient radioactive-water purification.

Performance Evaluation of Desalination Battery Systems based on Synthesis Method of Carbon Nanotube-Carbon Felt Composite Electrodes

To enhance chlorine ion removal and increase the current charging capacity of a desalination battery system, carbon nanotubes were applied to a carbonaceous electrode. Two types of composite electrodes were fabricated by attaching multiwalled carbon nanotubes (MWCNTs) to a carbon felt (CF) electrode via dip coating (D-CNT@CF) and electrophoresis (E-CNT@CF). These composite electrodes were then tested within a desalination battery system to evaluate their chlorine ion removal efficiency and current charging performance during the charging process. Microflocs of MWCNTs were observed on the surface of D-CNT@CF, whereas a uniform coating of MWCNTs was achieved on the surface of E-CNT@CF. Performance evaluations revealed that chlorine ion removal rates improved by 3.5% for D-CNT@CF and by 19.4% for E-CNT@CF compared to that of CF. Furthermore, the time required to reach maximum current charge was 40.0% for D-CNT@CF and E-CNT compared to CF. @CF decreased by 60.0%. These findings suggest that surface modification of carbonaceous electrodes through electrophoresis can result in a more stable coating and improve the performance of desalination battery systems.

Enhanced Cu-EDTA degradation with trace Cu(II) in limestone via activating PMS

Effective removal of heavy metal complexes from contaminated water remains a challenging task. In this work, a limestone/PMS system was constructed for the efficient degradation of Cu-EDTA. Under the conditions of 3.0 g/L limestone and 1.0 mM PMS, the degradation efficiency of 10.0 mg/L Cu-EDTA reached 99.0 % in 60 min, and the removal efficiency of Cu ions approached 50.0 %. The main active specie revealed by quenching and EPR experiments was the singlet oxygen (1O2). Interestingly, Trace amounts of Cu(II) in limestone react with PMS enhancing the degradation of Cu-EDTA. The results of the HPLC-MS analysis showed that the reactive species attacked the Cu–O and Cu–N bonds, as well as triggered a decarboxylation process, resulting in the decomposition of Cu-EDTA into six intermediates. Meanwhile, SEM and XPS analyses revealed that Cu ions released during the degradation of Cu-EDTA are deposited on the limestone surface as Cu(OH)2 and Cu2(OH)2CO3. In addition, the initial pH and co-existing ions have a weak effect on the system. Finally, a one-month continuous flow experiment showed that the degradation efficiency of Cu-EDTA was about 95.0 % and the removal efficiency of Cu ions was 40.0 %. In conclusion, this study provides a new approach for the destruction of metal complexes and the removal of heavy metals.

Evaluation and comparison of UiO66 and its functionalized variants for the removal of Cu (II) ions from wastewater

This study examined the effectiveness of polyvinyl chloride (PVC) mixed matrix membranes incorporating UiO66 and UiO66-NH2 metal-organic frameworks (MOFs) for removing varying concentrations of Cu (II) ions from wastewater. The findings indicated that adding UiO66-NH2 to the functionalized UiO (FUiO) membrane enhanced its porosity, pore size, hydrophilicity, and pure water flux. Furthermore, integrating UiO66-NH2 into the PVC matrix led to an impressive Cu (II) ion removal efficiency exceeding 99 %. The PVC-FUiO2 membrane also demonstrated about 93.5 % reusability after the first cycle. Overall, the results confirmed that the PVC-FUiO2 (Functionalized UiO66) membrane exhibited superior performance in terms of Cu (II) removal efficiency and shorter separation times across various Cu (II) concentrations compared to the unmodified membrane.

Ornamental Plant Growth in Different Culture Conditions and Fluoride and Chloride Removals with Constructed Wetlands

Natural water resources often contain fluorides and chlorides due to wastewater discharge; however, excessive exposure to fluorides can pose health risks to humans. Elevated chloride levels can negatively affect aquatic fauna and disrupt the reproductive rates of plants. This study assessed constructed wetlands (CWs) featuring monocultures (including Canna hybrid, Alpinia purpurata, and Hedychium coronarium) and polycultures (combinations of species from the monoculture systems) of ornamental plants (OPs) to evaluate their efficiency in removing fluorides and chlorides. The results revealed that the ornamental plants flourished in the CW conditions without sustaining any physical damage. C. hybrid demonstrated the longest roots and the highest volume, as well as greater height compared to other species. However, this did not affect the ion removal efficiency. In polyculture systems, 42.2 ± 8.8% of fluoride was removed, a result that was not significantly different (p &gt; 0.05) from the removal rates observed in monocultures of C. hybrid (42.5 ± 7.5%), H. coronarium (36.8 ± 7.0%), or A. purpurata (30.7 ± 7.9%). For chloride, a similar pattern emerged, with 32.4 ± 4.8% removed in constructed wetlands (CWs) using a polyculture of ornamental plants, a figure that was also not significantly different (p &gt; 0.05) from the removal percentages in monocultures of C. hybrid (29.1 ± 5.3%), H. coronarium (28.1 ± 5.0%), or A. purpurata (32.0 ± 5.7%). Our results indicate that CWs with polyculture species contribute to pollutant removal at levels comparable to those found in monoculture systems. However, polyculture systems offer enhanced aesthetic appeal and biodiversity, incorporating various ornamental flowering plants. The use of this eco-technology for removing fluoride and chloride pollutants helps prevent river contamination and associated health issues.

&amp;nbsp;Synthesis and Characterization of Chitosan-Based Schiff Base and Cu(II) Complex from Shrimp Shells and its Application on Catalysis and Bio-sorption

In recent years, metal complexes and biopolymers have gained significant attention in environmental applications such as catalysis and heavy metal removal. Chitosan, a biopolymer derived from chitin, is well-known for its biodegradability, non-toxicity, and strong metal ion affinity, which can be further enhanced through Schiff bases to improve its catalytic and adsorption capabilities. The primary objectives of this study were to investigate whether Cu(II) complex of Chitosan Salicylaldehyde Schiff Base CSSB-Cu(II) can act as an efficient catalyst in hydrogen peroxide decomposition reaction and to find out the raw absorbent which has the highest Cadmium ion removal efficiency from among the absorbents Chitin (CT), Chitosan (CS) and Chitosan Salicylaldehyde Schiff Base (CSSB). CSSB was synthesized using the Schiff condensation reaction between the amino group of CS and the carbonyl compound of salicylaldehyde with the elimination of water molecules and it was complexed with Cu(II) ion to produce CSSB-Cu(II) complex. The catalytic effect of the CSSB-Cu(II) complex on the kinetics of the decomposition of hydrogen peroxide was investigated and compared with CSSB. CSSB-Cu(II) showed a better catalytic effect than CSSB and has a pseudo-first-order catalytic decomposition for H2 O2 . CT, CS, and CSSB were investigated as adsorbents for the Cd(II) removal to determine their cadmium removal efficiencies. This study concludes that the removal efficiency of CSSB was greater than that of CS and CT. The equilibrium data agreed more with the Langmuir model than with the Freundlich model. The IR and electronic spectral data confirm the presence of an imine bond and the existence of the complex in square planar geometry.

Optimization of Electrodialysis for Ammonium Removal From NH4Cl-Doped Groundwater Samples Using the Response Surface Method.

This study aims to optimize ammonium removal from NH4Cl-enriched groundwater at different concentrations using an electrodialysis (ED) process. A customized design (CD) based on response surface methodology (RSM) was employed to develop predictive models and improve the performance of the demineralization system. Ion removal efficiency was evaluated in 32 unique experimental configurations, taking into account variations in three input parameters: voltage (A), initial ammonium concentration (B) and demineralization rate (C). These parameters were selected for their impact on two response variables: electric conductivity (Y1) and final ammonium concentration (Y2). An in-depth analysis of variance (ANOVA) was performed to examine the variables and their interactions. The results indicated that Y1 was significantly influenced by C, while Y2 was influenced by B. In addition, the predictive models demonstrated strong correlations, with a coefficient of determination (R2) greater than 0.88 for both response variables. The RSM approach applied to optimize the parameters studied identified the following optimum values: 14.17 V for A, 1 mg/L for B and 70 % for C, giving Y1 of 215.377 μS/cm and Y2 of 0.279 mg/L.

Exploiting RSM and ANN modeling methods to optimize phosphate ions removal using LDH/alginate composite beads

In the present work, layered double hydroxide (MgAl) and alginate composite beads (LDH/alginate) were developed and used as low-cost and environmentally friendly adsorbent for phosphate ions removal. The successful incorporation of sodium alginate into the LDH structure was confirmed through SEM analysis. The dried beads exhibited a notably rough surface, which promotes molecular movement and potentially enhances pollutant adsorption. The pH of zero charge point (pHPZC) of the composite was found to be 7.41. This result implies that negative ions have a tendency to draw positive charges on the adsorbent surface via electrostatic interaction forces when the pH is lower than the pHPZC. On the other hand, a surface that has a pH higher than pHPZC mostly has a negative charge. The percentage removal and adsorption capacity were investigated as a function of contact time.Experiments were carried out by simultaneously varying three factors, in order to evaluate and compare the predictive capabilities of the response surface methodology (RSM) and the artificial neural network approach (ANN) for the adsorption process. Both methods demonstrated a strong ability to accurately predict the adsorption process. However, the response surface methodology exhibited a lower prediction error compared to the artificial neural network approach.The central composite design within response surface methodology (CCD-RSM) was employed to optimize the experimental conditions for the adsorption process. The model, which considers three factors: adsorbent dose (A), initial concentration (B), and contact time (C), proved to be significant. Among these, the quadratic term (B2) had the most substantial impact on the phosphate ion adsorption rate. The analysis yielded an R2 value of 0.94, indicating an excellent fit to the data. The findings suggest that increasing contact time and reducing the initial concentration improve phosphate ion removal efficiency, while the adsorbent dose has little to no effect. The Artificial Neural Network (ANN) model effectively predicted the adsorptive remediation of phosphate ions onto LDH/alginate composite beads, achieving a high coefficient of determination (R2 = 0.984) between the model outputs and the experimental data. The study highlights the significant potential of LDH/alginate composite beads as a natural adsorbent for the removal of phosphate ions from aqueous solutions. These results underscore the environmental friendliness and efficiency of the adsorbent used for phosphate adsorption.

Mechanism of Enhanced Fluoride Adsorption Using Amino-Functionalized Aluminum-Based Metal–Organic Frameworks

Due to the increasing fluoride concentrations in water bodies, significant environmental concerns have arisen. This study focuses on aluminum-based materials with a high affinity for fluorine, specifically enhancing metal–organic frameworks (MOFs) with amino groups to improve their adsorption and defluorination performance. We systematically investigate the factors influencing and mechanisms governing the adsorption and defluorination behavior of amino-functionalized aluminum-based MOF materials in aqueous environments. An SEM, XRD, and FT-IR characterization confirms the successful preparation of NH2-MIL-101 (Al). In a 10 mg/L fluoride ion solution at pH 7.0, fluoride ion removal efficiency increases with the dosage of NH2-MIL-101 (Al), although the marginal improvement decreases beyond 0.015 g/L. Under identical conditions, the fluoride adsorption capacity of NH2-MIL-101 (Al) is seven times greater than that of NH2-MIL-101 (Fe). NH2-MIL-101 (Al) demonstrates effective fluoride ion adsorption across a broad pH range, with superior fluoride uptake in acidic conditions. At a fluoride ion concentration of 7 mg/L, with 0.015 g of NH2-MIL-101 (Al) at pH 3.0, adsorption equilibrium is achieved within 60 min, with a capacity of 31.2 mg/g. An analysis using adsorption isotherm models reveals that the fluoride ion adsorption on NH2-MIL-101 (Al) follows a monolayer adsorption model, while kinetic studies indicate that the predominant adsorption mechanism is chemical adsorption. This research provides a scientific basis for the advanced treatment of fluoride-containing wastewater, offering significant theoretical and practical contributions.

Synthesis and characterization of allyl mannitol cross-linker based novel hydrogel for capturing of toxic metal ions from aqueous solution

ABSTRACT Three grades of allyl-mannitol cross-linker-based hydrogel (AMCLHs hydrogel) have been synthesized with the help of acrylic acid and acrylamide monomers using a free radical co-polymerization technique. The three prepared grades of AMCLHs hydrogel have been referred to as AMCLHs-1, AMCLHs-2, and AMCLHs-3, respectively. The prepared AMCLHs hydrogels have been characterized by several analytical techniques viz. Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) analysis, point of zero charge (ΔpHPZC), analysis, and scanning electron microscope (SEM) analysis, respectively. The synthesized hydrogels have been utilized for the elimination of Cu2+ and Co2+ ions from wastewater. The properties of prepared AMCLHs hydrogels, i.e. swelling and water retention ratio have been studied in distilled water under optimized conditions. The maximum swelling ratio of the best grade of hydrogel (AMCLHs-1) has been found to be 400.5 g/g with the water retention ratio of 75.09% during 24 h. These findings indicate the AMCLHs-1 hydrogel has remarkable swelling and water retention capacity. The maximum metal ion removal efficiency of AMCLHs-1 hydrogel from aqueous solutions has been found to be 96.6% for Cu2+ and 94.2% for Co2+ ions under optimum conditions. The experimental data fitted well with the Langmuir and Freundlich adsorption models, revealing maximum adsorption capacities of 431.03 mg/g for Cu2+ ions and 414.93 mg/g for Co2+ ions, respectively. In addition, the rate for the adsorption of Cu2+ and Co2+ ions onto AMCLHs-1 hydrogel follows both Pseudo first and second-order kinetic models. The negative ΔG values indicate that the adsorption process occurs spontaneously, while positive ΔH values suggest that the adsorption process is exothermic in nature. The prepared AMCLHs hydrogel is reusable and exhibits high desorption efficiency with 87.63% for Cu2+ and 85.21% for Co2+ metal ions even after the fourth cycle. Overall, AMCLHs hydrogel is a cost-effective and reusable adsorbent that possesses a significant potential for heavy metal ion removal from aqueous solutions.

INVESTIGATION OF THE EFFICIENCY OF RHENIUM ION SORPTION USING ION-EXCHANGE RESINS POLYACRYLIC ACID: POLY-4-VINYLPYRIDINE IN VARIOUS RATIOS

This study is devoted to the study of the efficiency of sorption of rhenium ions using ion-exchange resins containing polyacrylic acid (PAK) and poly-4-vinylpyridine (P4VP) in various composition ratios. Goals and objectives. To investigate synthesized resins with different ratios of PAK:P4VP and to study their sorption capacity, kinetics and selectivity with respect to rhenium ions. Methods. Thanks to a comprehensive experimental analysis, including periodic sorption experiments and characterization methods such as spectrophotometry and atomic emission spectroscopy, the effect of resin composition on sorption efficiency was clarified during the study. Results and discussion. Optimal ratios have been determined to ensure maximum efficiency of rhenium ion removal. In addition, the study examines the main mechanisms governing sorption properties, with an emphasis on the relationship between resin composition, surface chemical composition and ion interaction. Conclusion. The results obtained contribute not only to the development of special ion-exchange materials for the effective extraction and purification of rhenium, but also contribute to a deeper understanding of ion sorption processes. This research has important implications for rhenium-dependent industries, offering strategies for solving problems related to its extraction, purification and use.