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

The feasibility of synthesizing tri-phasic TiO2 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 (A34.6R56.8B8.6) 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 TiO2 Nano-particles within chitosan biopolymer matrix exhibited significantly enhanced sorption performance toward Pb2+ and Cd2+ ions, reaching maximum removal efficiencies of 99.86% for Pb2+ and 97.85% for Cd2+ 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 Pb2+ and 68.72 mg/g for Cd2+. These results highlight the potential of the biopolymer-supported tri-phasic TiO2 Nano-composite as a sustainable and effective material for detoxifying heavy metals in water treatment applications.