Plasma-assisted catalysis decomposition of BPA over graphene-CdS nanocomposites in pulsed gas-liquid hybrid discharge: Photocorrosion inhibition and synergistic mechanism analysis

Abstract In this work, plasma-assisted catalytic degradation of bisphenol A (BPA) has been performed over series of the graphene-CdS (rGO(x)/CdS) nanocomposites in aqueous solution. A pulsed gas-liquid hybrid discharge (PHD) was proposed to induce the “pseudo photocatalysis” effect of the rGO(x)/CdS nanocomposites and promote the formation of ·OH radicals. Compared to pure CdS, the rGO(x)/CdS nanocomposites present narrower band gap, more appropriate conduction band position, and higher separation rate of electron-hole (e−-h+) pairs, which result in higher BPA degradation performance in plasma-assisted catalysis process. The highest degradation efficiency of 87.58% and energy efficiency of 4.22 mg/kJ were obtained after 60 min plasma-assisted catalytic degradation over rGO(5)/CdS, which are 20.05% and 0.97 mg/kJ higher than those in single PHD system. It is also worth noting that rGO can provide perfect protection to CdS, diminishing the photocorrosion and improving the stability of rGO(5)/CdS nanocomposite, and the leaching of Cd2+ greatly decreases from 3.32% to 0.96% in the gas-liquid plasma environment. The possible synergetic degradation mechanism and toxicological evaluation for BPA and its decomposition intermediates in the plasma-assisted catalysis process have been proposed according to the function analysis of reactive species, the identification of organic intermediates, theoretical density functional theory (DFT) calculation, as well as quantitative structure-activity relationship (QASR) analysis. The strategy of integrating PHD with rGO(x)/CdS nanocomposites proposed in this work is expected to offer a feasible and potential technique for the industrial application of organic wastewater treatment.