Evaluations of physico-chemical properties of TiO2/clinoptilolite synthesized via three methods on photocatalytic degradation of crystal violet

Abstract

Different preparation routes for TiO 2 -supported natural and synthetic clinoptilolite (TiO 2 /CP) composites were thoroughly investigated on the basis of sol–gel, hydrothermal, and in-situ hydrothermal methods. The micro-structural features and physicochemical properties of resultant TiO 2 /CPs were characterized via X-ray diffraction patterns, scanning (transmission) electron microscope images, Fourier transform infrared spectra, inductively coupled plasma-optical emission spectrometry methods, BET-isotherms, UV–visible spectra, and surface charge potential distributions. The results showed that in-situ hydrothermal method led to well dispersions of loaded-TiO 2 particles on the surface of leaf-like CP, while obviously aggregated TiO 2 on a relatively distorted structure of CP was obtained using sol–gel and hydrothermal methods. Their adsorptive and photocatalytic efficiencies for removal of crystal violet (CV) dye in aqueous solution were also explored under UV-irradiations. The results demonstrated that TiO 2 /CPs synthesized via sol–gel and in-situ hydrothermal methods presented the excellent performances with 98% removal efficiencies as compare to the bare commercial TiO 2 which achieved 53% removal of CV dye. While, the in-situ hydrothermally synthesized TiO 2 /CPs were the best due to their moderate energy cost, highest adsorption capacities and removal efficiencies. Particularly, the synthetic CPs as supports exhibited synergetic photocatalytic activities for the degradation of CV dye, which is attributed to their high surface areas, better adsorption capability, and fine dispersion of TiO 2 particles. Adsorption and degradation kinetics of CV dye were found to follow the pseudo-second and pseudo-first order models, respectively.