Synergistic degradation of bisphenol A by pulsed discharge plasma with granular activated carbon: Effect of operating parameters, synergistic mechanism and possible degradation pathway

Abstract

A hybrid gas-liquid pulsed discharge plasma (PDP) system combined with granular activated carbon (GAC) was established to investigate the bisphenol A (BPA) degradation. The results exhibit excellent synergistic effect in PDP with GAC system (combination system) for BPA degradation. 4 g amount of GAC, 20 mg/L BPA concentration, acidic solution condition and higher gas flow rate are beneficial for BPA degradation; The highest BPA removal efficiency, mineralization and kinetics constants can reach 98.7%, 34.6% and 0.075 min−1 respectively. The decreased O3 and enhanced •OH in water after GAC addition illustrate O3 can be catalyzed by GAC and lead to the formation of •OH. The radical scavenger test illustrates the role of •OH during BPA degradation. The aviation of nature and concentration of fluorophores during BPA degradation is explored by three-dimensional excitation emission fluorescence spectra. Organic acids including formic acid, acetic acids, oxalic acid and inorganic acid including nitric acid and nitrous acid can be produced during pulsed discharge and BPA degradation. The intermediates during the BPA degradation were identified by liquid chromatograph-mass spectrometer (LC-MS). Based on the intermediates, the proposed degradation pathway is presented. The SEM technology demonstrates that GAC can be regenerated by the discharge process.