Zeolite Na-A supported TiO2: Effects of TiO2 loading on structural, optical and adsorption properties

Abstract

Zeolite Na-A supported TiO2 nanopowders were synthesized via a modified sol–gel technique and the effects of TiO2 loading were characterized for thermal, structural, morphological, optical and textural behaviour. Thermal properties predicted a minimum annealing temperature of 600 °C whereas the X-ray diffraction (XRD) patterns indicated that the composite was highly crystalline, and consisted of both TiO2 and zeolite Na-A peaks. Scanning electron microscopy (SEM) images confirmed that the TiO2 nanoparticles occurred mainly on the surface of the zeolite Na-A support. Nitrogen adsorption–desorption studies portrayed increased porosity and larger surface area for TiO2/zeolite Na-A compared to pure TiO2. The optical band gap decreased with increased TiO2 loading from 3.17 to 2.85 eV. The synthesized nanopowders were applied in photocatalytic dye removal, where by the highest degradation rate for the supported TiO2 was realized at 1.5 %TiO2/zeolite Na-A loading. It was found that loading beyond 1.5 %TiO2 led to a structural collapse and decline in the photodegradation rate.