State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237, China.
Environ Technol. 2011 Jul;32(9-10):1063-71. doi: 10.1080/09593330.2010.525750.
Clofibric acid (CA), a metabolite of lipid regulators, was investigated in ultra-pure water and sewage treatment plant (STP) effluent at 10 degrees C under UV, vacuum UV (VUV), UV/H2O2 and VUV/H2O2 processes. The influences of NO3-, HCO3- and humic acid (HA) on CA photolysis in all processes were examined. The results showed that all the experimental data well fitted the pseudo-first-order kinetic model, and the apparent rate constant (k(ap)) and half-life time (t(1/2)) were calculated accordingly. Direct photolysis of CA through UV irradiation was the main process, compared with the indirect oxidation of CA due to the slight generation of hydroxyl radicals dissociated from water molecules under UV irradiation below 200 nm monochromatic wavelength emission. In contrast, indirect oxidation was the main CA degradation mechanism in UV/H2O2 and VUV/H2O2, and VUV/H2O2 was the most effective process for CA degradation. The addition of 20 mg L(-1) HA could significantly inhibit CA degradation, whereas, except for UV irradiation, the inhibitive effects of NO3- and HCO3- (1.0 x 10(-3) and 0.1 mol L(-1), respectively) on CA degradation were observed in all processes, and their adverse effects were more significant in UV/H2O2 and VUV/H2O2 processes, particularly at the high NO3- and HCO3- concentrations. The degradation rate decreased 1.8-4.9-fold when these processes were applied to a real STP effluent owing to the presence of complex constituents. Of the four processes, VUV/H2O2 was the most effective, and the CA removal efficiency reached over 99% after 40 min in contrast to 80 min in both the UV/H2O2 and VUV processes and 240 min in the UV process.
氯贝酸（CA）是一种脂质调节剂的代谢物，在 10°C 下，分别在紫外线、真空紫外线（VUV）、紫外线/过氧化氢（UV/H2O2）和 VUV/H2O2 工艺中，于超纯水和污水处理厂（STP）废水中进行了研究。考察了 NO3-、HCO3-和腐殖酸（HA）对所有过程中 CA 光解的影响。结果表明，所有实验数据均符合准一级动力学模型，并相应计算了表观速率常数（k（ap））和半衰期（t（1/2））。与在低于 200nm 单色波长发射的 UV 辐射下从水分子中解离出的羟基自由基对 CA 的间接氧化相比，通过紫外线照射直接光解 CA 是主要过程。相比之下，在 UV/H2O2 和 VUV/H2O2 中，间接氧化是 CA 降解的主要机制，而 VUV/H2O2 是 CA 降解最有效的工艺。添加 20mgL（-1）的 HA 会显著抑制 CA 的降解，而除了紫外线照射之外，在所有过程中，NO3-和 HCO3-（分别为 1.0x10（-3）和 0.1molL（-1））对 CA 降解的抑制作用也有所观察，并且在 UV/H2O2 和 VUV/H2O2 工艺中，其不利影响更为显著，特别是在高浓度的 NO3-和 HCO3-的情况下。由于实际 STP 废水中存在复杂的成分，这四个过程的降解速率降低了 1.8-4.9 倍。在这四个过程中，VUV/H2O2 是最有效的，与 UV/H2O2 和 VUV 工艺分别需要 80min 和 40min 相比，在 40min 后 CA 的去除效率超过 99%，而在 UV 工艺中则需要 240min。
