Integrated photocatalysis-adsorption method for chromium wastewater treatment

Abstract

Nowadays, the development of TiO2-based composite materials has received much attention as part of an effort to increase TiO2′s photocatalytic activity so that it can be used in large-scale waste treatment. TiO2-natural zeolite (TiO2-NZ) hybrid composites, as an integrated photocatalysis-adsorption system, have been synthesized using the sol-gel method with varied zeolite masses (1.5, 3.0, and 4.5 g). The photodegradation of Cr(VI) by TiO2-NZ composites was tested, and it was discovered that the sample with a variation of 1.5 g zeolite (TiO2-NZ/1.5) produced the highest Cr(VI) degradation. The combination of natural zeolite adsorption and TiO2 photocatalytic properties has resulted in an increase in the material's photocatalytic ability to degrade Cr(VI). The TiO2-NZ/1.5 sample has the highest Cr(VI) removal rate of up to 97 percent, according to our findings. Crystal changes, morphology, porosity, elemental composition, and optical properties of the composite with superior performance were investigated using XRD, SEM-EDS, the N2-adsorption-desorption isotherm, and UV–vis DRS. TiO2 synthesized by the sol-gel method was in the anatase phase and successfully immobilized on the zeolite surface. The incorporation of TiO2 on the surface of the zeolite has suppressed the crystal size and band gap energy of TiO2. On the other hand, the presence of TiO2 has increased the specific surface area of the zeolite. In general, a larger specific surface area can show better adsorption ability and provide more active sites in photocatalytic reactions.