Degradation of Bisphenol A and S in Wastewater during Cold Atmospheric Pressure Plasma Treatment

Abstract

Developing novel, fast and efficient ecologically benign processes for removing organic contaminants is crucial for pawing the sustainable development in water treatments. For this reason, this study investigates the implementation of Cold Atmospheric pressure Plasma (CAP) generated in ambient air as an efficient agent for removal of Bisphenol A (BPA) and Bisphenol S (BPS)—known endocrine disrupting compounds in water and wastewater, by monitoring degradation kinetics and its transformation products. The highest removal efficiencies of BPA (>98%) and BPS (>70%) were obtained after 480 s of CAP exposure. A pseudo-first-order kinetic revealed that BPA (-kt = 0.0044 ̶ 0.0090 s−1) degrades faster than BPS (-kt = 0.0004 ̶ 0.0023 s−1) and that the degradation is also time- and CAP power-dependent, while the initial concentration or matrix type had a negligible effect. This study also tentatively identified three previously reported and one novel transformation product of BPA and four novel transformation products of BPS. Their postulated structures suggested similar breakdown mechanisms, i.e., hydroxylation followed by ring cleavage. The results demonstrate that CAP technology is as efficient or better in process duration and removal efficiency than other advanced oxidation processes but has the advantage of not requiring additional chemicals and needs a modest amount of electrical energy, making it a highly promising treatment for water and wastewater remediation.