Oxidative degradation of Bisphenol A in aqueous solution using cobalt ion-activated peroxymonosulfate

Abstract

The degradation of Bisphenol A (BPA) in aqueous solution by an advanced oxidation process (AOP) involving cobalt ion activation of peroxymonosulfate (PMS) was investigated, in order to optimize the effectiveness of the PMS/Co system for complete mineralization of Bisphenol A in aqueous media. Batch degradation experiments were carried out in a 500 mL capacity quartz reactor under varied conditions of Co2+ ion source, pH, oxidant and catalyst dosage/ratio and time. The effect of humic acid addition on the degradation process was as well assessed. A technique was adapted for monitoring the degradation process by means of high-performance liquid chromatography. Results obtained show clearly that Co-activated PMS was very efficient for the degradation of BPA in water, due to action of strongly oxidizing sulfate radical anion (SO4−) and hydroxyl radical (OH). Both CoSO4 and CoCl2 as catalysts yielded complete degradation of BPA under different conditions. The time interval to complete degradation increased for higher BPA concentrations, whereas the trend of degradation rate with pH was pH 5 > pH 9 > pH 7. The presence of humic acid in water hindered the degradation performance of Co/PMS in a time-dependent manner. Quantum chemical computations performed to assess the local reactivity of the BPA molecule and to identify the reactive regions in terms of radical (F) and electrophilic attack (F−), revealed that radical attack would be initiated on the aromatic ring and olefinic double bonds. The present study has revealed that the PMS/Co2+ oxidation process has the capacity to completely remove and mineralize Bisphenol A from aqueous solution.