Photocatalytic degradation in aqueous solution using quantum-sized ZnO particles supported on sepiolite

Quantum-sized ZnO particles supported on sepiolite (ZnO/sepiolite) was prepared by sol-gel method using the sepiolite of acid activation as carrier, zinc acetate dihydrate (Zn(CH₃COO)₂·2H₂O) and lithium hydroxide monohydrate (LiOH·H₂O) as raw material. The size of ZnO which supported on fibrous sepiolite is about 5nm when calcined at 200°C. The behavior of ZnO/sepiolite composites in the degradation of C.I. Reactive Blue 4 was investigated. Under the optimal preparation conditions, when the content of ZnO was about 70wt.% in the nanocomposites, the photocatalytic property of the ZnO/sepiolite was excellent. The degradation rate of 20mg/L C.I. Reactive Blue 4 could get to 98% in 120min at room temperature when the concentration of catalyst was 0.2g/L. The photocatalytic decomposition of organic pollutants accords with a pseudo first-order kinetic. The pH and H₂O₂ influence the degradation rate of the ZnO/sepiolite. The experiment indicated that after the catalyst had been used 5 times repeatedly, the degradation rate had been still above 80%.