Degradation of rhodamine B by UV combined with sodium percarbonate (SPC): influencing factors and mechanism studies

The UV/SPC process was employed for the removal of rhodamine B (RhB), and the influences of reaction parameters and natural water components on the degradation of RhB were systematically studied. The results demonstrate that RhB can be efficiently eliminated in the UV/SPC system compared to using UV photolysis or SPC oxidation alone, with •OH and CO 3 •− being the main radicals to degrade RhB. The degradation efficiency of RhB was enhanced with increasing SPC concentration but decreased with increasing initial RhB concentration. Moreover, the degradation efficiency of RhB decreased with the increasing initial pH. When pH increased from 3 to 11, the degradation efficiency of RhB declined from nearly 100 to 81.93% within 20 min. Natural organic matter (NOM) and anions (Cl − and HCO 3 − ) exhibited an inhibitory effect on the degradation of RhB in the UV/SPC system, and the inhibitory effect was aggravated with the increase of NOM and anion concentrations. Consequently, there was a decrease in the degradation efficiency of RhB in the UV/SPC system in real water compared to pure water. The byproducts generated during the degradation of RhB were attributed to hydroxylation, N -deethylation, and C-O bond cleavage. Some intermediate products from RhB degradation still pose relatively high environmental risks, while most have low environmental hazards.