Efficient degradation of chlortetracycline in water by ultrasound activation of flexible ZnCoO doped PVDF membranes with high β phase

Abstract

Piezo-catalysis technology is considered an emerging technology to remove organic pollutants from wastewater. In this study, a ZnCoO@PVDF membranes with high-voltage electrical properties was prepared for the piezo-catalytic degradation of chlortetracycline (CTC) in wastewater. The entry of Co into the main lattice of ZnO changes the electrical properties of ZnO. The d33 test shows that Co increases the piezoelectric coefficient of ZnO by 6.5 times. Under ultrasonic conditions, the Zn0.8Co0.2O@PVDF membranes exhibit the best piezo-catalytic activity, with a degradation rate constant of 0.2027 mM−1, which is 34.94 times higher than that of pure PVDF. At the same time, the doping of Zn0.8Co0.2O caused the change of the crystal form of PVDF, the β phase with piezoelectric properties increased significantly, and the piezoelectric coefficient increased from 27.3 pC/N of PVDF to 44.7 pC/N. Multiple by-products and degradation pathways were identified using LC-MS, and two main degradation pathways were proposed based on density functional theory (DFT) calculations. The toxicity of CTC and its by-products was estimated using Toxicity Estimation Software Tool (TEST) software, which further confirmed the reduction of environmental risk after piezoelectric catalytic degradation. This study provides new insights into the efficient piezo-catalytic treatment of antibiotic wastewater.