Abstract:

A CaMoO₄ photocatalyst with high activity for degradation of aureomycin hydrochloride was prepared by sol-gel method. The phase structure, purity, functional group, surface morphology, optical properties and photocatalytic activity of the CaMoO₄ photocatalyst were investigated by various characterization methods. The results showed that the CaMoO₄ photocatalyst was tetragonal phase, and a small amount of C-O functional groups were present in the sample. The particles were approximately spherical, which consisted of large particles and fine particles. It had high visible-light response with an optical band gap value of 3.21 eV. The photocatalytic activity of CaMoO₄ photocatalyst was studied at different drug concentrations, catalyst dosages and pH values using aureomycin hydrochloride as the target for degradation. The results showed that the degradation percentage reached 94% at the drug mass concentration of 200 mg/L, photocatalyst dosage of 1 g/L and pH of 7. The photocatalytic mechanism of the CaMoO₄ photocatalyst was proposed based on experimental results and band theory. The mechanism study showed that the C-O functional groups provided extra energy for electron transition to the conduction band of the CaMoO₄ photocatalyst and promoted the generation of electron hole pairs. Holes, hydroxyl radicals and superoxide radicals were the key factors to promote the degradation of aureomycin hydrochloride.

Key words: sol-gel method, CaMoO₄, photocatalytic mechanism, conduction band, free radical