Comparison of UV/H2O2, UV/PMS, and UV/PDS in Destruction of Different Reactivity Compounds and Formation of Bromate and Chlorate

Abstract

In this study, we compared the decontamination kinetics of various target compounds and the oxidation by-products (bromate and chlorate) of PMS, PDS, and H 2 O 2 under UV irradiation (UV/PMS, UV/PDS, UV/H 2 O 2). Probes of different reactivity with hydroxyl and sulfate radicals, such as benzoic acid (BA), nitrobenzene (NB), and trichloromethane (TCM), were selected to compare the decontamination efficiency of the three oxidation systems. Experiments were performed under acidic, neutral, and alkaline pH conditions to obtain a full-scale comparison of UV/peroxides. Furthermore, the decontamination efficiency was also compared in the presence of common radical scavengers in water bodies [bicarbonate, carbonate, and natural organic matter (NOM)]. Finally, the formation of oxidation by-products, bromate, and chlorate, was also monitored in comparison in pure water and tap water. Results showed that UV/H 2 O 2 showed higher decontamination efficiency than UV/PDS and UV/PMS for BA degradation while UV/H 2 O 2 and UV/PMS showed better decontamination performance than UV/PDS for NB degradation under acidic and neutral conditions. UV/PMS was the most efficient among the three processes for BA and NB degradation under alkaline conditions, while UV/PDS was the most efficient for TCM degradation under all pH conditions. In pure water, both bromate and chlorate were formed in UV/PDS, small amounts of bromate and rare chlorate were observed in UV/PMS, and no detectable bromate and chlorate were formed in UV/H 2 O 2. In tap water, no bromate and chlorate were detectable for all three systems.

Chloride-Mediated Enhancement in Heat-Induced Activation of Peroxymonosulfate: New Reaction Pathways for Oxidizing Radical Production

“…Despite the lower BrO 3 – formation yields observed with heat/PMS-Cl – , the BrO 3 – levels detected under varying R Cl/Br conditions (Figure S16) substantially exceeded the maximum contaminant level for BrO 3 – in drinking water (10 μg/L) in most cases. This appears to be linked with the earlier findings that the use of persulfate instead of H 2 O 2 in photoinduced activation facilitated the occurrence of oxyhalides such as ClO 3 – and BrO 3 – . , BrO 3 – more effectively formed during persulfate activation due to (i) the preferred one-electron oxidation of Br – by SO 4 •– and (ii) direct oxidation of Br – to HOBr by PMS . As a countermeasure to mitigate BrO 3 – formation, the potentials roles of PMS and SO 5 •– /S 2 O 8 •– in scavenging X • /X 2 •– and reducing HOBr, respectively, could be explored.…”

“…− and BrO 3 − . 57,58 BrO 3 − more effectively formed during persulfate activation due to (i) the preferred one-electron oxidation of Br − by SO 4…”

Comparison of ribavirin degradation in the UV/H2O2 and UV/PDS systems: Reaction mechanism, operational parameter and toxicity evaluation

“…Meanwhile, NOM also could scavenge SO 4 •- under UV/PDS [12] . Meanwhile, the scavenging effect of NOM on SO 4 •- was also significant [15] , [16] . But based on our calculations, we found the contribution of sulfate radicals to the degradation of ribavirin is slightly increased from 0.03 to 0.06%.…”

New Insight into the Degradation of Sunscreen Agents in Water Treatment Using UV-Driven Advanced Oxidation Processes

“…The data revealed that the ε values for H2O2 and its dissociated form HO2 − were 19.6 and 229 M −1 cm −1 were higher than those for HSO5 − (the monovalent form of PMS) and SO5 2− , the divalent form of PMS (13.8 and 149.5 M −1 cm −1 , respectively). Furthermore, the quantum yield of H2O2 photolysis at 254 nm was determined to be Φ = 0.5, whereas the quantum yield of PMS photolysis at the same wavelength was measured as Φ = 0.52 [58]. Consequently, the slightly better performance of the UV/PMS/H2O2 system can be attributed to the efficient absorption of UV light facilitating H2O2 and PMS photolysis, which leads to an increased amount of ROS.…”