Efficient microwave-assisted photocatalytic degradation of endocrine disruptor dimethyl phthalate over composite catalyst ZrO_x/ZnO

A highly active ZrO_x/ZnO catalyst for microwave-assisted photocatalytic (MW/PC) degradation of endocrine disruptor dimethyl phthalate (DMP) has been prepared via cetyltrimethylammonium assisted hydrothermal method. The ZrO_x/ZnO was characterized by XPS, XRD, UV-Vis, BET and SEM techniques. The XPS result showed that Zr oxides with different valences (+2, +3, +4) co-existed in ZrO_x/ZnO. By using the ZrO_x/ZnO (0.1 g), the TOC removal efficiency of DMP (100 mL of 50 mg/L) was 88% after 30 min reaction, which was about 15% higher than P25 TiO₂. It was found that the removal process of DMP by MW/PC followed pseudo first-order kinetics in all cases, and ZrO_x/ZnO significantly accelerated the degradation of DMP. The degradation half-life time of DMP was shortened 45% compared with P25 TiO₂. A possible catalytic mechanism was proposed based on microwave response and interfacial charge transfer. ZrO_x/ZnO could be reused for six times without obvious decrease in catalytic activity. The study offers new insights into designing highly efficient catalysts for MW/PC process and is applicable for MW/PC environmental remediation.