Degradation of dimethyl phthalate by peroxomonosulfate ion activated by Zn–NiO x catalyst

Abstract

Zn–Ni oxide (Zn–NiO x ) was prepared by the sol–gel method using egg white. The degradation process of the reactants was studied to remove dimethyl phthalate by using Zn–NiO x catalysts to generate powerful radicals from peroxomonosulfate. The results showed that the best experimental conditions were that Zn–NiO x concentration, the ratio between peroxomonosulfate ion and dimethyl phthalate and initial pH was 100 mg/L, 30:1 and 4.4 ± 0.1, with 79.16% dimethyl phthalate degraded. The X-ray diffraction (XRD) pattern of the catalysts showed Ni2O3, NiO, ZnO and Zn phases. X-ray photoelectron spectroscopy (XPS) showed that relative ratio of Zn, Ni2+ and surface hydroxyl groups (–OH) decreased by 2.7, 9.0 and 10.4% after the reaction, indicating that the electron transfer between multivalence as well as the existence of –OH might enhance the degradation process during the advanced oxidation system. Besides, the average grain size was in the 25–45 nm range as determined by scanning electron microscopy (SEM), which was nearly the same as that calculated using the Scherrer formula through XRD.