The absorption of water at 25.0" f 0.1" C was examined on samples of boron phosphate preheated to loo", 200", or 300°C. The BET (nitrogen) surface areas and the total amount of water adsorbed increase with preheat temperature. The quantity of water physically adsorbed and that chemisorbed are both much greater than would be expected from the nitrogen surface areas. However, the amount of water chemisorbed may be accounted for on the basis of a single layer of water molecules.
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.
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