Microstructure-guided design of biopolymer-supported tri-phasic TiO2 for sustainable lead and cadmium detoxification

Abstract

Abstract The feasibility of synthesizing tri-phasic TiO 2 Nano-particles via the sol-gel method and their immobilization within chitosan biopolymer matrix was investigated. Structural characterization using XRD, HR-TEM, FTIR, and UV-vis DRS confirmed the successful formation of a stable hetero-structure consisting of anatase, rutile, and brookite phases (A 34.6 R 56.8 B 8.6 ) with strong interfacial interactions within the biopolymer matrix. Reduced direct and indirect band gaps to 2.97 and 2.58 eV, respectively, demonstrated improved optical characteristics under sunlight. The immobilized tri-phasic TiO 2 Nano-particles within chitosan biopolymer matrix exhibited significantly enhanced sorption performance toward Pb 2+ and Cd 2+ ions, reaching maximum removal efficiencies of 99.86% for Pb 2+ and 97.85% for Cd 2+ at pH 7, with equilibrium contact times of 90 and 120 min, respectively. According to the Langmuir isotherm model, the maximum removal capacities were 73.67 mg/g for Pb 2+ and 68.72 mg/g for Cd 2+ . These results highlight the potential of the biopolymer-supported tri-phasic TiO 2 Nano-composite as a sustainable and effective material for detoxifying heavy metals in water treatment applications.