Effects of UV/PS and UV/H2O2 on Degradation of Natural Organic Matter and Formation Potential of Haloacetonitriles in Surface Water

Abstract

This study aimed to investigate how degradation of organic matters in surface water by ultraviolet-activated persulfate (UV/PS) contributed to mitigation of formation of haloacetonitriles (HANs) comparing with conventional UV-activated hydrogen peroxide (UV/H 2 O 2 ). A surface water sample containing 10 mM of PS or H 2 O 2 was irradiated up to 3,000 mJ/cm 2 of 254 nm UV lump. Consequently, 3,000 mJ/cm 2 of UV/PS reduced formation potentials (FP) of dichloroacetonitrile (DCAN) and bromochloroacetnitrile (BCAN) from 3.8 to 0.2 µg/L and 2.8 to 0.6 µg/L, respectively. UV/H 2 O 2 also showed similar tendencies but reductions of DCAN and BCAN were less significant. However, both UV/PS and UV/H 2 O 2 were likely to increase FP of dibromoacetonitrile (DBAN). Additionally, correlation coefficient tests indicated that degradation of chromophore aromatic compounds and ful - vic acid-like substances by both UV/PS and UV/H 2 O 2 showed significant correlations with reduction of DCAN-FP. Degradation of some fluorophore aromatic proteins by UV/PS correlated to reduction of BCAN-FP, while increase of other portions of fluorophore aromatic proteins by UV/H 2 O 2 correlated to increase of DBAN-FP. Precursors of DCAN were easily decomposed by both treatments, whereas precursors of brominated HANs (BCAN and DBAN) were not preferentially attacked by them. However, strong oxidation potential of UV/PS achieved decomposition of these organic moieties.