Enhanced adsorption of diclofenac sodium on the carbon nanotubes-polytetrafluorethylene electrode and subsequent degradation by electro-peroxone treatment

Abstract

Effective adsorption of pharmaceuticals and then degradation of them in the regeneration process are attractive for their complete removal from water or wastewater. The adsorption of diclofenac sodium (DS) on the prepared carbon nanotubes-polytetrafluorethylene (CNTs-PTFE) anode was enhanced in the presence of applied voltage. Compared with open circuit adsorption, the initial adsorption rate and adsorbed amount of DS in static adsorption experiments increased 2.1 and 1.2 times, respectively. After adsorption, the CNTs-PTFE anode was changed to cathode to in-situ degrade the adsorbed DS, and all DS was degraded after 10min using the electro-peroxone treatment. The mineralization efficiency increased with increasing ozone concentrations and current intensity, and complete mineralization of DS was achieved at 100mA and 27mg/L O3 after 1h treatment. The regenerated CNTs-PTFE electrode kept stable adsorption capacity for DS in five adsorption-degradation cycles. This CNTs-PTFE electrode has a promising application for the removal of pharmaceuticals from water or wastewater via the electrosorption and subsequent oxidative degradation, and the electro-peroxone process is an effective method to regenerate the spent electrode and mineralize the adsorbed pollutants.