Experimental and theoretical assessment of selected pollutants treated with gamma radiation and hydrogen peroxide

Abstract

Degradation of ibuprofen, triclosan, diclofenac, and ketoprofen in real wastewater effluent by gamma radiation/hydrogen peroxide was investigated on the basis of removal efficiencies, G-values, and kinetics. Gamma irradiation was performed using a60Co source irradiator in the presence of different concentrations of hydrogen peroxide. The analyses of the pollutants were performed before and after irradiation treatment using a Liquid Chromatography-Mass Spectrometry (LC-MS) system. The addition of 0.5% hydrogen peroxide resulted in an enhanced removal efficiency of the target pollutants (93.92% for ibuprofen, 99.47% for triclosan, 86.65% for diclofenac, and 86.32% for ketoprofen) compared with the performance of the gamma irradiation process alone. The rate constants (k) of ibuprofen, triclosan, diclofenac, and ketoprofen increased by 1.42, 2.38, 1.38, and 3.37 times with 0.5% hydrogen peroxide addition, respectively. Moreover, the 90% decomposition of the target pollutants was achieved at lower doses in the gamma-ray/hydrogen peroxide system in comparison with the gamma treatment without hydrogen peroxide. Fukui functions and dual descriptor were calculated using density functional theory (DFT) to investigate the sensitivity of the target pollutants to hydroxyl radical attacks, to identify the initial reaction pathway, and to predict the degradation by-products. The findings were consistent with literature mechanisms and observed by-products.