Degradation of triclosan in the combined reaction of Fe²⁺ and UV-C: Comparison with the Fenton and photolytic reactions

The degradation mechanism of triclosan, which is a potent broad-spectrum antimicrobial agent considered to be an emerging pollutant, was investigated using the Fenton reaction, UV-C only, and the combined reaction of Fe ²⁺ and UV-C. In the Fenton, UV-C only, and combined reactions, triclosan was almost completely removed within 60 min, whereas total organic carbon (TOC) was degraded by only 48.2, 58.7, and 79%, respectively, within 150 min. The production of chloride as the ionic byproduct in the Fenton, UV-C only, and combined reactions reached 54, 62, and 78%, respectively, after 150 min. In the presence of methanol as an OH radical scavenger, the efficiencies of triclosan removal and chloride production decreased significantly in all reactions, indicating that the OH radical is the main oxidizing compound in these reactions. The concentration of Fe²⁺ decreased continuously during the Fenton reaction, whereas it increased after 90 min in the combined reaction, indicating that a reversible reaction between Fe²⁺ and Fe³⁺ occurred. The more efficient removal of TOC and the generation of more OH radicals by the combined reaction indicate that it is superior to other reactions for the degradation of triclosan.