Roles of Activated Carbon in UV/Chlorine/Activated Carbon-TiO 2 Process for Micropollutant Abatement and DBP Control.

The ultraviolet (UV)/chlorine process has attracted increasing attention for micropollutant abatement. However, the limited hydroxyl radical (HO • ) generation and the formation of undesired disinfection byproducts (DBPs) are the two major issues in this process. This study investigated the roles of activated carbon (AC) in the UV/chlorine/AC-TiO 2 process for micropollutant abatement and DBP control. The degradation rate constant of metronidazole by UV/chlorine/AC-TiO 2 was 3.44, 2.45, and 1.58 times higher than those by UV/AC-TiO 2 , UV/chlorine, and UV/chlorine/TiO 2 , respectively. AC acted as an electron conductor and dissolved oxygen (DO) adsorbent, resulting in the steady-state concentration of HO • that was ∼2.5 times that of UV/chlorine. Compared with UV/chlorine, the formation of total organic chlorine (TOCl) and known DBPs in UV/chlorine/AC-TiO 2 was reduced by 62.3 and 75.7%, respectively. DBP could be controlled via adsorption on AC, and the increased HO • and decreased chlorine radical (Cl • ) and chlorine exposure reduced DBP formation. UV/chlorine/AC-TiO 2 efficiently abated 16 structurally different micropollutants under environmentally relevant conditions owing to the enhanced generation of HO • . This study provides a new strategy for designing catalysts with photocatalytic and adsorption properties for UV/chlorine to promote micropollutant abatement and DBP control.