摘要
介绍了一种UV/H2O2光氧化体系降解微囊藻毒素MC-LR的动力学模型。根据UV光分解、H2O2和·OH氧化MC-LR的反应以及稳态近似法,导出了MC-LR降解的动力学方程。解释了体系中H2O2、HO-2、CO2-3、HCO-3等对降解MC-LR动力学的影响。实验结果表明,在一定的光强和H2O2浓度情况下,由于反应产生的CO2-3、HCO-3和HO-2等离子的影响,UV/H2O2光氧化MC-LR的过程只能近似用准一级动力学方程描述。
The paper aims to present a kinetic model for MC-LR degradation by processing UV/H_2O_2 developed by the authors to predict the microcystins destruction in drinking water supply. The degradation process of MC-LR by UV/H_2O_2 actually include the known elementary chemical and photochemical reactions, in which there exist synergetic effects between UV photolysis and H_2O_2 oxidation, In order to develop the model, the degradation process has to be divided into three sections, that is, UV photolysis, H_2O_2 oxidation and hydroxyl radical oxidation. The hydroxyl radical generated from the decomposition of H_2O_2 under the UV irradiation is responsible for the synergetic effect. The concentration of hydroxyl radical and the observed rate constant can be deduced by using the steady-state approximation in the hydroxyl radical oxidation in accordance with a series of reactions initiated by hydroxyl radicals. And, then, the effect of UV light intensity, the dosage of H_2O_2, the concentration of carbonate and bicarbonate anion on the observed rate constant can be analyzed in detail. With the amount of hydroxyl radical increased and the UV photolysis action enhanced, the UV light intensity will in turn strengthened, which can then help to improve the degradation markedly to some extent. However, the UV light intensity does not enhanced in direct proportion to the degradation rate of MC-LR. At lower range of the H_2O_2 dosage, the degradation of MC-LR seems to get improved significantly with the increase of H_2O_2. Nevertheless, the degradation of MC-LR tended to get retarded obviously with H_2O_2 increased to a larger dosage due to the hydroxyl radical scavenged by the ions and radicals in the solution. The concentration of carbonate and bicarbonate anion generated in the solution tends to increase along with the degradation process, which would inhibit the degradation of MC-LR due to the scavenging effect to hydroxyl radical. And, finally, a simplified kinetic model for the degradation of MC-LR with UV/H_2O_2 is described, which can help to better understand for MC-LR degradation.
出处
《安全与环境学报》
CAS
CSCD
2005年第3期33-36,共4页
Journal of Safety and Environment
基金
教育部南开大学-天津大学共建项目"废水和微污染水处理创新技术研究"
