Efficacies of UVC and VUV photolysis for mineralization of pharmaceutical compounds in mixed aqueous solution

The usefulness of ultraviolet-C (UVC: 254 nm) and vacuum UV (VUV: 185 + 254 nm) photolysis for elimination and mineralization of four selected pharmaceutical compounds (PhCs) in mixed aqueous solution were tested in laboratory batch experiments. UVC photolysis was unable to eliminate moderate and refractory PhCs. Moreover, it was not at all useful for mineralization of the PhCs (<10% TOC removal, 30 min reaction) and longer reaction period (i.e. 60 min) had no significant positive impact on the mineralization efficiency. On the other hand, VUV photolysis eliminated the PhCs almost completely in a short reaction period irrespective of their nature, and 90% mineralization was achieved in an hour. The greatly enhanced elimination and mineralization efficiencies for VUV photolysis were attributed to accelerated direct and indirect photolysis reactions. Based on the results, it was concluded that VUV photolysis was very promising over UVC photolysis for mineralization of PhCs in mixed aqueous solution. However, more studies are necessary for practical applicability of the method in wastewater treatments.