Low-cost Zeolite/TiO2 composite for the photocatalytically enhanced adsorption of Cd2+ from aqueous solution

Nano-TiO2 (anatase) powders were immobilized on crystalline zeolite (size = 45 µm). The composite material was used for the rapid and efficient adsorption of the Cd2+ ions from an aqueous solution. Furthermore, the composites were exposed to two different calcination temperatures (500 and 700 °C) and were characterized by employing XRD, UV–Vis DRS, EDX, XRF, and pH point of zero charge analyses. Green synthesis, impregnation method was used to obtain zeolite-supported TiO2. The present study demonstrated that the photocatalytic maximum adsorption capacity of Cd2+ by zeolite-supported TiO2 (qm = 59.3 mg/g) was 3.7 times higher than that of bare TiO2 (qm = 16.2 mg/g). The percent removal efficiency of 99.6% was observed using zeolite-supported TiO2 composite under compact fluorescent light. Adsorption and kinetics studies were performed and the results obtained best fitted Langmuir adsorption isotherm and pseudo-second-order kinetics. As the wastewater containing different ionic strength, model dye Methylene Blue (MB) was used as competitive ions in the adsorption process. MB acted as photo-generated positive hole (h+) trapper and enhanced the Cd2+ removal efficiency (qm = 68.8 mg/g) further by reducing electron/hole pairs recombination rate. The easily separable composite showed high reusability by physical (high-temperature combustion) regeneration as compared to chemical (Fenton oxidation) regenerated samples.