Sustainable heavy metal (Cr(VI) ion) remediation: Ternary blend approach with chitosan, carboxymethyl cellulose, and bioactive glass

Heavy metal pollution poses a significant environmental challenge to worldwide, especially in developing countries. This study focuses on eliminating the heavy metal chromium (VI) ion from wastewater, employing an eco-friendly and economical ternary blend composed of Chitosan (CS), Carboxymethyl cellulose (CMC), and bioactive glass (BAG). The innovative bioactive glass is crafted from biosilica extracted from biowaste of cow dung ash, calcium oxide from eggshell ash, and phosphorus pentoxide. The CS/CMC/BAG blend is prepared via sol-gel method and characterized using XRD, FT-IR, TGA, BET, TEM and SEM revealing a porous structural morphology during blending. Batch adsorption studies explore various parameters such as pH, adsorbent dose, contact time and initial metal ion concentrations. The results are then evaluated through adsorption kinetics and adsorption isotherms (Langmuir, Freundlich, D-R, and Temkin isotherm modeling). The investigation concludes that the optimal conditions for Cr (VI) removal are pH 3, contact time of 300 min, adsorbent dosage of 0.5 g, and an initial metal ion concentration of 50 ppm. The adsorption isotherm model indicates an excellent fit with the Freundlich isotherm (R2 = 0.9576) and pseudo-second-order kinetics (R2 = 0.981). In summary, the CS/CMC/BAG ternary blend exhibits a remarkable ability to effectively remove heavy metal Cr(VI) ions from industrial wastewater.