Sulfate radical anion: Laser flash photolysis study and application in water disinfection and decontamination

Abstract

[EN] Sulfate radicals (SO4 center dot-) reactivity against gram-negative (E. coli) and gram-positive (E. faecalis) bacteria and Contaminants of Emerging Concern (CECs) (Diclofenac-DCF, Sulfamethoxazole-SMX and Trimethoprim-TMP) was investigated through laser flash photolysis (LFP) technique. Analysis of the lifetime of SO4 center dot- in presence of cell-wall compounds of bacteria and CECs allowed determining reactivity of SO4 center dot- towards these compounds. Results showed that SO4 center dot- reacts with common cell-wall components through H-abstraction mechanism (kSO4 center dot ¿ < 108 M-1s-1). By contrast, kSO4 center dot ¿ > 109 M-1s-1 were found using aromatic amino acids (AAA) only present in Porins of the gram-negative outer-membrane. The intermediates detected from the reaction of SO4 center dot- with the AAA confirmed the involvement of electron transfer processes. Moreover, kSO4 center dot ¿ values determined for DCF, TMP and SMX also agreed with an electron transfer mechanism. Interestingly, bacteria and CECs removal at pilot plant scale by UV-C/SO4 center dot- is in accordance with the kSO4 center dot ¿ obtained using the LFP: E. coli > E. faecalis and DCF > TMP approximately equal to SMX.