基于kintecus模型的紫外/次氯酸降解MC-LR的自由基稳态浓度及反应动力学模拟

Simulation of steady-state radical concentration and reaction kinetics of MC-LR degradation by UV/hypochlorous acid based on kintecus model

蓝藻代谢产生的微囊藻毒素-LR(MC-LR)会污染饮用水源,并对人类健康构成威胁。紫外/次氯酸技术能产生氯自由基(Cl·)和羟基自由基(HO·)等强氧化性物质来降解MC-LR。但该技术的最优参数尚不可知,已报导的实验结果仅能提供部分参数,亟需通过数值模拟来确定更多重要参数。因此,采用kintecus化学动力模型模拟了先前报导过的实验数据并对未报导数据进行了预测。结果表明,模型预测值与实验值的变化趋势一致,误差在1.5倍以内。在pH为6时,紫外/次氯酸技术对MC-LR的降解效果最好,7 min左右降解率可达到90%。HO·和Cl·的稳态浓度分别为6.59×10^(-14) mol·L^(-1)和1.22×10^(-14) mol·L^(-1),与原文献实验结果较为吻合(7.89×10^(-14) mol·L^(-1),0.93×10^(-14) mol·L^(-1))。在次氯酸添加量超过40μmol·L^(-1)之后,降解效果提升并不明显。当紫外光波长由257.7 nm增加到301.2 nm时,MC-LR的表观降解速率常数由5.07×10-3 s^(-1)下降到4.69×10-3 s^(-1),下降了7.5%。而在波长为257.7 nm、pH由6提升至8时,表观降解速率常数由5.07×10^(-3) s^(-1)下降到3.84×10^(-3) s^(-1),下降了24%。因此,改变pH对降解效率的影响大于改变紫外光波长的情况。

Microcystin-LR(MC-LR) produced by the metabolism of cyanobacteria will contaminate drinking water sources and threaten the human health. UV/Hypochlorous acid technology can generate strong oxidizing substances such as chlorine radicals(Cl·) and hydroxyl radicals(HO·) to degrade MC-LR. However, the optimal parameters of this technology have not yet been known, and the reported experimental results can only provide some parameters. Thus, numerical simulation is urgently needed to determine more important parameters.Therefore, the kintecus chemical kinetic model was used to simulate the previously reported experimental data and predict the unreported data. The results showed that the predicted values of the model were consistent with the experimental values, and the errors were within 1.5 times. When the pH was 6, the UV/hypochlorous acid technology had the best performance on MC-LR degradation, and the degradation rate could reach 90% within7 minutes. The steady-state concentrations of HO· and Cl· were 6.59×10^(-14) mol·L^(-1) and 1.22×10^(-14) mol·L^(-1),respectively, which were in accordance with the experimental results of the original literatures(7.89×10^(-14) mol·L^(-1), 0.93×10^(-14) mol·L^(-1)). After the concentration of hypochlorous acid exceeded 40 μmol·L^(-1), the degradation rate remained constant. When the wavelength of ultraviolet light increased from 257.7 nm to301.2 nm, the apparent degradation rate constant of MC-LR decreased from 5.07×10^(-3)s^(-1) to 4.69×10^(-3)s^(-1), a decrease of 7.5%. When the wavelength was 257.7 nm and the pH increased from 6 to 8, the apparent degradation rate dropped from 5.07×10^(-3)s^(-1) to 3.84×10^(-3)s^(-1) with a decrease rate of 24%. Therefore, the effect of pH on the degradation efficiency was greater than that of ultraviolet light wavelength.