Removal of Lead from Contaminated Water Using a Green-Synthesized Carboxylated Cellulose Ion Exchange Adsorbent

This technical report describes ongoing research on the development of a green-synthesized, cellulose-based weak acid ion-exchange resin for the removal of Pb2+ from industrial effluent. Cellulose oxalate (COX) was prepared via esterification of cellulose in a choline chloride–oxalic acid deep eutectic solvent (DES), aiming to produce a high-capacity, regenerable, and environmentally benign ion-exchange material. Wheat straw was investigated as a sustainable cellulose feedstock, while analytical-grade cellulose served as a reference for synthesis optimization and adsorption studies. COX synthesis was optimized using response surface methodology based on a central composite design, with carboxyl content as the primary response variable. Material characterization included Fourier transform infrared spectroscopy (FTIR), optical microscopy, yield analysis, and titrimetric determination of carboxyl functionality. The adsorption performance of COX toward Pb2+ was evaluated through batch kinetic and isotherm studies, followed by preliminary fixed-bed column experiments to assess dynamic adsorption behavior under continuous-flow conditions. Metal ion concentrations were quantified using UV–Vis spectrophotometry based on dithizone complexation. This report summarizes the current methodology, preliminary results, and experimental framework, with additional performance validation, regeneration studies, and pilot-scale analysis ongoing.