Synthesis of natural porous minerals supported TiO2 nanoparticles and their photocatalytic performance towards Rhodamine B degradation

Natural porous mineral supported (TiO2/diatomite) photocatalyst was prepared via a modified sol–gel method using titanium (IV) butoxide (TBOT) and diatomite. The effect of TBOT dosage on adsorption capacity and photocatalytic activity for Rhodamine B (RhB) solution was investigated. The morphology and elemental distribution were determined by scanning electron microscopy with attached energy-dispersive X-ray detector. The porous and crystalline structures were characterized using nitrogen adsorption–desorption and X-ray diffraction techniques, respectively. The prepared TiO2/diatomite hybrid catalyst has shown relatively even porous structure and dispersion of TiO2 over the surface. This suggests that the diatomite matrix prevented the agglomeration of TiO2 particles. Initially, the surface area and pore volume of the hybrid catalyst were increased by adding TBOT then decreased for dosages higher than 1.0 ml. The crystalline size of TiO2 immobilized on diatomite matrix by sol–gel method was around 20 nm. When the experiments were carried out in the absence of diatomite, this value was increased to 33.73 nm. The use of diatomite also promoted an increase of the transformation temperature of the crystalline phase anatase to rutile for the TiO2. The as-prepared TiO2/diatomite composite exhibited high photocatalytic activity (96.0% for 0.5 h UV-light irradiation) for the degradation of RhB from wastewater as a result of its unique porous structure and optimum TiO2 loading. In addition, it can be easily separated from suspension and possess a good durability. This hybrid material holds great promise in the engineering field for the environmental remediation.