Cu nanoparticles grafting on the surface of ZnO nanostructures to boost the porosity and surface area for effective removal of manganese ions from aqueous solutions

Designing highly adsorptive materials for wastewater treatment via facile approaches is still challenging. To boost the recovery of heavy metals from wastewater, surface and structure modification are considered a successful route. Herein, we report the design of ZnO nanoparticles by a simple thermal decomposition method followed by grafting Cu nanoparticles (Cu NPs) over the ZnO surface. Cu/ZnO was prepared with different Cu ratios, 0.01 and 1%. It was found that incorporating Cu into ZnO improved the porosity and surface area of ZnO. The adsorption ability of Cu/ZnO compared with bare ZnO was studied towards removing manganese ions from wastewater. The effects of several parameters, such as pH, temperature, contact time, and initial ion concentrations, were studied. The maximum removal of manganese was found at pH 2, 20 °C after 60 min in the presence of 1 g/L adsorbent. The role of Cu grafted on the surface of ZnO was discussed. The rates of adsorption were found to follow the pseudo-second-order model. The results showed better fitting to Freundlich isotherm. The thermodynamic study revealed that the sorption process is spontaneous, exothermic, and favorable at low temperatures. The free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes were calculated to predict the nature of adsorption.

3D-Printed Filters for Efficient Heavy Metal Removal from Water Using PLA@CS/HAP Composites

Chitosan/Hydroxyapatite composites, enriched with relatively active -NH2 and -OH groups, have emerged as promising adsorbents for heavy metal removal. In this study, we harnessed the potential of CS/HAP composites by developing monolithic PLA@CS/HAP filters utilizing 3D printing and freeze-drying techniques. These filters possess both macroscopic and microscopic porous structures, endowing them with exceptional capabilities for removing heavy metals from water. The adsorption properties of CS/HAP composites were explored by varying the dosage, duration, and initial concentrations of copper ions. The maximum adsorption capacity for Cu2+ was determined to be approximately 119+/-1 mg/g at the natural pH and 298 K. Notably, the monolithic PLA@CS/HAP filters demonstrated remarkable efficiency in the removal of copper ions, with 90% of copper ions effectively removed within a mere 2-h period in a cyclic adsorption experiment. Furthermore, the PLA@CS/HAP filters exhibited a robust dynamic Cu2+ removal capacity (80.8% or even better in less than 35 min) in a dynamic adsorption experiment. Importantly, all materials employed in this study were environmentally friendly. In summary, the PLA@CS/HAP filter offers advantages such as ease of preparation, eco-friendliness, versatility, and broad applicability in diverse wastewater treatment scenarios, thereby presenting a significant potential for practical implementation.

Chitosan-Based Nanocomposite Polymeric Membranes for Water Purification-A Review

During the past few years, researchers have focused their attention on developing innovative nanocomposite polymeric membranes with applications in water purification. Natural and synthetic polymers were considered, and it was proven that chitosan-based materials presented important features. This review presents an overview regarding diverse materials used in developing innovative chitosan-based nanocomposite polymeric membranes for water purification. The first part of the review presents a detailed introduction about chitosan, highlighting the fact that is a biocompatible, biodegradable, low-cost, nontoxic biopolymer, having unique structure and interesting properties, and also antibacterial and antioxidant activities, reasons for using it in water treatment applications. To use chitosan-based materials for developing nanocomposite polymeric membranes for wastewater purification applications must enhance their performance by using different materials. In the second part of the review, the performance's features will be presented as a consequence of adding different nanoparticles, also showing the effect that those nanoparticles could bring on other polymeric membranes. Among these features, pollutant's retention and enhancing thermo-mechanical properties will be mentioned. The focus of the third section of the review will illustrate chitosan-based nanocomposite as polymeric membranes for water purification. Over the last few years, researchers have demonstrated that adsorbent nanocomposite polymeric membranes are powerful, important, and potential instruments in separation or removal of pollutants, such as heavy metals, dyes, and other toxic compounds presented in water systems. Lastly, we conclude this review with a summary of the most important applications of chitosan-based nanocomposite polymeric membranes and their perspectives in water purification.

Scalable Synthesis of Hide Substance-Chitosan-Hydroxyapatite: Novel Biocomposite from Industrial Wastes and Its Efficiency in Dye Removal

A novel porous polymer-inorganic hybrid biocomposite with various functional groups (hide substance/chitosan/hydroxyapatite) has been synthesized in simple, economic, and scalable process utilizing leather industry solid waste and seafood industry waste composed with hydroxyapatite. Physicochemical characterization of the material reveals formation of composites with homogenous distribution of the constituents in the material matrix. The composite is hard and porous (with 0.1632 cm3/g slit-shaped mesopores and micropores) having particle sizes 40-80 μm and a Brunauer-Emmett-Teller surface area of 55.54 m2/g. The material is polycrystalline in nature with a fair amount of amorphous substance and less hydrophilic in character than constituent polymers. The dye removal efficiency of the material has been tested with two model dyes, namely, methylene blue (MB) (cationic/basic dye) and sunset yellow (SY) (anionic/acid dye). Optimum adsorptions of 3.8 mg MB (pH 12, RT ≈ 27 °C) and 168 mg of SY (pH 3, RT ≈ 27 °C) have been found per gram of the composite material. Langmuir isotherm and pseudo second order rate models have been found to be the best-fit models to explain the equilibrium isotherm and kinetics of the adsorption process for both the dyes. However, higher and faster adsorption of SY in comparison with MB indicated higher binding efficiency of the material toward the acidic dye. Desorption of dyes from the dye-adsorbed material was studied using a suitable eluent of appropriate pH and recycling for five times showed without loss of efficiency. The prepared composite showed very high dye removal efficiency toward four different commercially used dyes (496 mg/g of Orange-NR, 477 mg/g of Red-VLN, 488 mg/g of Blue-113 dye, and 274 mg/g of Green-PbS dye) from their individual and cocktail solutions. It was also efficient to decolorize dye-bearing tannery exhaust bath. Hence, waste materials generated during industrial processes could be efficiently used for the decontamination of colored wastewater produced by various industries.

Precipitation, adsorption and rhizosphere effect: The mechanisms for Phosphate-induced Pb immobilization in soils-A review

Lead (Pb) is one of the most toxic heavy metals that pose a direct threat to organisms and it can not been degraded through microbial activities or chemical reaction. Bioavaibility and eco-toxicity of Pb which mostly depend on Pb chemical speciation play an important role in the remediation of Pb-contaminated soils. Phosphate (P) amendments which could transfer Pb from unstable fraction to stable fraction are commonly used to immobilize Pb in soils and have been extensively studied by researchers during decades. Based on the previous study, it can be concluded that three principal mechanisms may be responsible for P-induced Pb immobilization: 1) the precipitation of Pb-phosphates, including direct precipitation, ion-exchange (or substitution) effect and liming effect; 2) the adsorption of Pb, including the direct adsorption and the adsorption of Pb to iron (hydr)oxides; 3) the rhizosphere effect, including acidification effect and mycorrhizae effect. In this review, these mechanisms have been completely discussed and the internal relationships among them were summarized to give a better understanding of P-induced Pb immobilization in soils and promote the development of P-based remediation technology.

Synthesis of guar gum-g-(acrylic acid-co-acrylamide-co-3-acrylamido propanoic acid) IPN via in situ attachment of acrylamido propanoic acid for analyzing superadsorption mechanism of Pb(ii)/Cd(ii)/Cu(ii)/MB/MV

GG-g-(AA-co-AM-co-APA) IPN superadsorbent, characterization of loaded microstructures and individual/synergistic adsorption mechanism of MB/SF/Pb(ii)/Cd(ii)/Cu(ii) are reported.

Selective dissolution of halide perovskites as a step towards recycling solar cells

Most research on perovskite solar cells has focused on improving power-conversion efficiency and stability. However, if one could refurbish perovskite solar cells, their stability might not be a critical issue. From the perspective of cost effectiveness, if failed, perovskite solar cells could be collected and recycled; reuse of their gold electrodes and transparent conducting glasses could reduce the price per watt of perovskite photovoltaic modules. Herein, we present a simple and effective method for removing the perovskite layer and reusing the mesoporous TiO2-coated transparent conducting glass substrate via selective dissolution. We find that the perovskite layer can be easily decomposed in polar aprotic solvents because of the reaction between polar aprotic solvents and Pb(2+) cations. After 10 cycles of recycling, a mesoporous TiO2-coated transparent conducting glass substrate-based perovskite solar cell still shows a constant power-conversion efficiency, thereby demonstrating the possibility of recycling perovskite solar cells.

Mesoporous carbonated hydroxyapatite/chitosan porous materials for removal of Pb(ii) ions under flow conditions

Mesoporous carbonated hydroxyapatite/chitosan porous materials are fabricated for the first time, which show good adsorption properties for Pb(ii) ions even under flow conditions.

Efficient and fast removal of Pb(ii) by facile prepared magnetic vermiculite from aqueous solution

Magnetic modified vermiculite was prepared by a simple one-pot solvothermal method to remove lead from aqueous solution.