固定在颗粒活性炭中的TiO_2光催化降解阿特拉津

Photocatalytic Degradation of Atrazine with TiO_2 Fixed on Granular Activated Carbon(GAC)

利用30W低压汞灯作光源,采用固定颗粒活性炭中的TiO2(TiO2/GAC)作光催化剂,在浅盘反应器中考察了阿特拉津溶液的光催化降解。结果表明,在平均光强为4.38mW·cm-2,光催化剂投加量为7.0g·L-1,阿特拉津初始浓度为21.9mg·L-1,3wt%H2O2用量为30μL·15mL-1,投加方式为1次·2h-1,光照时间为6～10h时,去除率可达92.7%～94.7%,TOC去除率可达67.1%～78.3%。光催化剂增至10g·L-1,H2O2用量一次性加60μL,光照时间为3～4h时,去除率可达91.6%～93.7%,TOC去除率可达65.9%～73.9%。通过组合实验和紫外光谱图分析,估计了体系中影响去除率的光催化、吸附、光降解、H2O2的作用性质和大小,并估计了降解途径,认为同时存在侧链脱烷基反应和OH取代Cl的反应,在有H2O2存在时,使前反应较强。TOC值测定表明阿特拉津已从8个碳降至含2～3个碳的物质。

The photocatalytic degradation of atrazine under UV radiation with TiO2/GAC was investigated, in terms of irradiation average intensity, amount of TiO2/GAC used, initial concentration of atrazine and amount of 3wt% H2O2. The results showed that under the following conditions, namely, 4.38 mW· cm- 2, 7.0 g· L- 1, 21.9 mg· L- 1 and 30 μ L· 15 mL- 1 ( one time· 2 h- 1), respectively, after 6～ 10 h irradiation, the removal rates achieved 92.7% ～ 94.7 % , TOC removals were 67.1% ～ 78.3 % , respectively. When the amount of TiO2/GAC increased to 10 g· L- 1 and amount of H2O2 was 60 μ L ( one time), after 3～ 4 h irradiation, the removal rates could achieve 91.6% ～ 93.7% . Based on the combination experiments and analysis of UV spectrums, the extent and characteristic of the effects of photocatalysis, adsorption and photolysis existed in present system on the removal rates and the degradation rates were estimated. It may be proposed that the replacement reaction of Cl by OH and dealkylation exist together. Addition of H2O2 made dealkylation stronger than the replacement reaction. The result of TOC measurement also showed that atrazine was degraded from 8 carbon atoms into the substance contained 2～ 3 carbon atoms.