Removal of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) in water by oxidative, reductive, thermal or photochemical treatments

Removal of a highly potent Ames mutagen, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) with decrease of its mutagenic potency from an aqueous solution by oxidative (ozonation and addition of H 2O 2 with or without ferrous ion), reductive (addition of Na 2SO 3, Na 2S 2O 4 and ascorbic acid), thermal (heating in a boiling water bath) and photochemical (UV irradiation) treatments were investigated. More than 97% of removal of MX (initial amount of 1 mM) and its mutagenicy was achieved by the treatments with O 3 Fe 2+ and H 2 O 2 Fe 2+ . Hydroxyl radical was an important reactant in these treatments, since the removal of MX was strongly inhibited by the addition of typical hydroxyl radical scavengers, mannitol and L-tryptophan methyl ester. The removal of 1 mole of MX required 2 moles of hydroxyl radical accompanied by the release of 2 moles of chloride ion. In the thermal and photochemical treatments, 59% and 76% of MX and the same portions of its mutagenic potency were removed during 60 min, respectively. The release of 2 moles of chloride ion from 1 mole of MX were also observed in these treatments, but hydroxyl radical did not participitate in the decomposition. In the reductive treatments, 68% of MX was removed by the addition of Na 2SO 3 during 60 min. However, the decrease of mutagenic potency was 48%. It was strongly suggested that the lack of regularity between the amount of removed MX and the decrease of its mutagenic potency is due to weak addition of SO 3 2− to MX rather than reduction of MX.