Effect of Calcium and Magnesium on the Photocatalytic Oxidation of Humic Acid in Water over TiO_2
钙镁离子对二氧化钛光催化氧化水中腐殖酸的影响

Photocatalytic oxidation of humic acid in water was studied in the presence of calcium and magnesium using TiO2 powder as photocatalyst. The adsorption of humic acid on the photocatalyst was also studied. A cylindrical borosilicon reactor was used as batch photoreactor and a 125 W UV lamp(Emax=365 nm) was used as central light source. The results showed that the photocatalysis is an effective method for removal of humic acid as trihalomethanes precursor in water. The photocatalytic removal rate of humic acid was enhanced in the presence of calcium and magnesium, this may be due to cationic ion bridging between humic acid molecules as well as between humic acid molecule and the surface of titanium dioxide particle, led to the increase of adsorption amount of humic acid on TiO2. The effects of cations concentration and TiO2 dosage on the photocatalytic process were also discussed. Based on the following experimental conditions: HA C0=20 mg/L, Ca2+]=80 mg/L, pH=7, TiO2]=1 mg/ml, 100% color, almost 100% HA concentration and >95% TOC were removed under irradiation 2.5 h.