A novel chitosan-glutamic acid membrane for multi-pollutant amputation: Investigational and RSM optimizations

Novel ACS film for efficient dual adsorption of Cr(VI) and SDS: Mechanistic insights and practical applications

The current study introduces a novel ACS film as a dual-functional adsorbent for the efficient elimination of hexavalent chromium (Cr(VI)) and sodium dodecyl sulphate (SDS) from aqueous systems. Comprehensive batch experiments were directed, and the results were rigorously validated using Response Surface Methodology (RSM). The maximum adsorption capacity was found to be 467.14 and 244.47 mg g-1 for Cr(VI) and SDS, respectively. The adsorption of Cr(VI) followed the Freundlich isotherm model (R2 = 0.985), indicating multilayer adsorption, while SDS adhered to the Langmuir isotherm (R2 = 0.935), suggesting monolayer adsorption. Kinetic studies revealed that Cr(VI) adsorption was best defined by the Pseudo Second Order model (R2 = 0.994), whereas SDS adsorption conformed to the Pseudo First Order model (R2 = 0.975), elucidating distinct adsorption mechanisms. Thermodynamic analyses confirmed that the adsorption processes for both Cr(VI) and SDS were spontaneous and enthalpy-driven. The film performance was evaluated using real effluent samples from textile industries, demonstrating its practical applicability in complex matrices. Additionally, regeneration studies showed sustained adsorption efficiency across five cycles, highlighting the materials reusability and economic viability. This work emphasizes the potential of the ACS film as a versatile and sustainable material for addressing dual pollution challenges, paving the way for scalable applications in environmental remediation.

Enhanced fluoride removal with sequentially modified alginate biopolymer: Insights from mathematical and column models

This study investigates the use of brown algae-derived alginate biopolymer to improve fluoride (F-) removal in water treatment. It compares two modified alginate-based adsorbents: zirconium-crosslinked alginate (AZ) and a newly developed material created by combining ferric aluminosilicate laterite (FASL), a mining by-product, with alginate and crosslinking it with zirconium, called ALZ. Both AZ and ALZ were synthesized and characterized using SEM-EDX, FT-IR, TGA-DTA, XRD, XRF, and BET. Their ability to remove fluoride from aqueous solutions was tested, achieving over 70 % removal efficiency through process optimization with response surface methodology (RSM). The adsorption process followed the Langmuir isotherm and pseudo-second-order kinetics. Increasing temperature improved fluoride adsorption for both materials, with maximum capacities at 30 °C and 50 °C: 70.27 mg g-1 and 117.64 mg g-1 for AZ, and 170.14 mg g-1 and 410.81 mg g-1 for ALZ, respectively. Thermodynamic analysis confirmed the process was spontaneous across all temperatures. Mathematical modelling was also used to predict fluoride breakthrough. This research provides valuable insights for developing efficient methods to address fluoride contamination, with both industrial and drinking water samples tested. The synthesis process demonstrated environmental sustainability, with a low environmental-factor (E-factor) of 0.023, highlighting its eco-friendly nature.

Chitin extraction from crab shells and synthesis of chitin @metakaolin composite for efficient amputation of Cr (VI) ions

The present research study combines chitin from shrimp waste with the oxide-rich metakaolin. Metakaolin is a blend of mixed oxides rich in silica and alumina with good adsorbent properties. The chitin@metakaolin (CHt@M.K.) composite was synthesized and characterized using FTIR, SEM, TGA, XRD and XPS techniques. Cr(VI) removal studies were compared for chitin and CHt@M.K. through adsorption. It was found that the adsorption capacity of CHt@M.K. is 278.88 mg/g, almost double that of chitin, at pH 5.0 in just 120 min of adsorption. Isotherm models like Langmuir, Freundlich, Temkin and Dubinin-Radushkevich were investigated to comprehend the adsorption process. It was revealed that Langmuir adsorption isotherm is most suitable to elucidate Cr(VI) adsorption on CHt@M.K. The adsorption kinetics indicate that pseudo first order was followed, indicating that the physisorption was the process that limited the sorption process rate. The positive enthalpy change (20.23 kJ/mol) and positive entropy change (0.083 kJ/mol K) showed that the adsorption process was endothermic and more random at the solid-liquid interface. The negative free energy change over entire temperature range was an indicator of spontaneity of the process. Apart from all these, the non-covalent interactions between Cr(VI) and composite were explained by quantum calculations based models.

Granulation of hydrometallurgically synthesized spinel lithium manganese oxide using cross-linked chitosan for lithium adsorption from water

A drastic increase in demand for electric vehicles and energy storage systems increases lithium (Li) need as a critical metal for the 21st century. Lithium manganese oxides stand out among inorganic adsorbents because of their high capacity, chemical stability, selectivity, and affordability for lithium recovery from aqueous media. This study investigates using hydrometallurgically synthesized lithium manganese oxide (Li1.6Mn1.6O4) in granular form coated with cross-linked chitosan for lithium recovery from water. Characterization methods such as SEM, FTIR, XRD, and BET reveal the successful synthesis of the composite adsorbent. Granular cross-linked chitosan-coated and delithiated lithium manganese oxide (CTS/HMO) adsorbent demonstrated optimal removal efficiency of 86 % at pH 12 with 4 g/L of adsorbent dosage. The Langmuir isotherm at 25 °C, which showed monolayer adsorption with a maximum capacity of 4.94 mg/g, a better fit for the adsorption behavior of CTS/HMO. Adsorption was endothermic and thermodynamically spontaneous. Lithium adsorption followed the pseudo-first-order kinetic model.