Mineralization of sucralose by UV-based advanced oxidation processes: UV/PDS versus UV/H2O2

Abstract

Mineralization of sucralose (SUC) in water by UV-based photolysis processes (i.e., direct UV, UV/peroxydisulfate (PDS) and UV/H2O2) was explored in this work. The effects of oxidant concentration, initial sucralose concentration and pH on TOC removal were investigated. The results indicated that the mineralization of sucralose increased with higher concentrations of oxidant and decreased with the increase of initial sucralose concentration and it is reported that the UV/PDS system can completely mineralize SUC after 60min using a 30-fold excess of oxidant over SUC molar concentration. Raising the solution pH from 3 to 11 inhibited the mineralization of SUC slightly in the UV/PDS process, while the mineralization rate increased from pH 3 to 7 and decreased in alkaline conditions in the UV/H2O2 process. TOC removal of 2%, 70% and 93% of sucralose (initial concentration 0.126mM) were achieved in 60min by the UV, UV/H2O2 and UV/PDS processes, respectively, when 2.520mM oxidants were used at neutral pH. Different inorganic anions were found to have an effect on the efficiency of these UV-based AOPs in the order NO2−>NO3−>Cl−. Contrary to previous work, where the presence of NO2− almost completely inhibited the mineralization of SUC by UV-based AOPs systems, it has been found that the mineralization rates decreased dramatically to 0.0005min−1, especially when the concentration of NO2− exceed 1mM. Toxicity tests with activated sludge investigated the efficiency of the UV-based AOPs on the detoxification of the solutions as the oxidation proceeded.