Sono-photo-assisted heterogeneous activation of peroxymonosulfate by Fe/CMK-3 catalyst for the degradation of bisphenol A, optimization with response surface methodology.

Abstract

The present study examined the removal of bisphenol A (BPA) and total organic carbon (TOC) from aqueous solutions by the Fe/CMK-3 as peroxymonosulfate activator used in the sono-photo-catalytic process. The synthesis of Fe/CMK-3 was carried out using the co-precipitation method, and it was characterized by FTIR, XRD, BET, EDX, and TEM. The results showed that the iron nanoparticles were uniformly embedded in the CMK-3 pores. The effect of factors affecting on the removal of BPA and TOC was evaluated by response surface methodology (RSM) with center composite design (CCD). The analysis of variance of the quadratic model showed that the model is significant (p value<.0001 and R2 >99.4%) and can be used to optimize the removal efficiency of BPA. Optimization results showed that the highest removal efficiency of BPA (100%) and TOC (80.6%) was achieved in optimum conditions of pH 7.8, catalyst dose 0.33g/L, PMS dose 3.35mmol/L, BPA concentration 39.3mg/L, and 78.5min. In addition, statistical analysis of the data showed that, in the studied range, the initial concentration of BPA was the most influential factor, followed by pH and PMS dose. Highest catalytic stability of Fe/CMK-3 showed the potential applicability of catalyst in the treatment of BPA-containing solutions. The quenching test showed that sulfate radical was the main responsible for the removal of BPA. The decrease in IOUR value after the 75-min reaction time indicates that this process has a high ability for oxidation of the pollutant and its intermediates. Generally, the observed results suggest that the Fe-CMK-3/UV/US/PMS system can be a promising procedure for the removal of persistent pollutants such as BPA from aqueous media. PRACTITIONER POINTS: Fe/CMK-3 exhibited prominent catalytic activity and high stability for peroxymonosulfate activation. Effective degradation of bisphenol A was achieved in the Fe-CMK-3/UV/US/PMS system. The effect of five factors at five levels and their interactions during the removal of BPA was evaluated by RSM method coupled with central composite design (CCD). The analysis of variance of the quadratic model showed that the model is very significant (p value<.0001) and can be used to optimize the removal efficiency of BPA. The quenching test showed that sulfate radical was the main responsible for the removal of BPA. Reducing IOUR value after the 75-min reaction time indicates that toxicity of the solution was significantly decreased in this system.