ZnO-based solar photocatalysis for treatment of Cr(VI) contamination

A novel photocatalytic technique was developed for the removal of Cr(VI) from electroplating discharge. Semiconductor dioxide (ZnO) was used to displace traditional TiO2 as a catalyzer. Solar irradiation was applied instead of the UV light for easier technical transfer to the industry in the future. After the optimization process of experimental conditions, solar photoreduction was performed and the concentration of Cr(VI) in electroplating discharge decreased from original 17.2 mg/L to 0.05 mg/L, leading to a removal rate of 99.7%. Cr(VI) concentration in final discharge after the treatment was far below the standard stated in National Industry Discharge Criteria of China.