rGO/NF as anode electrocatalytically activates persulfate combined coagulation process for tetracycline hydrochloride wastewater removal

Abstract

In this paper, reduced graphene oxide-modified nickel foam (rGO/NF) was utilised as an activator for peroxymonosulfate (PMS) in the electrocatalytic oxidation reaction and combined with a coagulation process to form the combined system of E-rGO/NF-PMS and coagulation in order to improve the pollutant degradation efficiency and shorten the reaction residence time. Various analytical methods were employed to characterise the electrode materials and the formed flocs in detail, and the effects of key parameters, such as applied voltage, PMS dosage, pH, and coagulant dosage, on the whole system were investigated by orthogonal experimental design. The results showed that the coagulation performance of the wastewater was enhanced by the electrocatalytic oxidation treatment, and tetracycline hydrochloride was effectively degraded by the addition of coagulant through adsorption of electro-neutralisation and net trapping and sweeping, and the concentration and chemical oxygen demand (COD) removal were 97.19 % and 91.97 %, respectively. In addition, the intermediate products generated from the degradation of pollutants were analysed in depth by using electron spin resonance (ESR), liquid chromatography-mass spectrometry (LC-MS), Fourier transform infrared spectroscopy (FTIR) and other techniques, focusing on the mechanism of action and degradation pathway of the combined coagulation process of electrocatalysis. In conclusion, the combined system of E-rGO/NF-PMS and coagulation overcame the shortcomings of long electrocatalytic oxidation time and coagulation time, and poor COD treatment effect, and provided new ideas and technical references for the future practical wastewater treatment engineering.