摘要
采用镍铁双金属为还原剂,对土壤中共存的7种多氯联苯（PCBs）的还原降解速率及其影响因素进行了试验研究和建模分析。试验结果表明,随着与镍铁双金属反应时间延长,7种PCBs呈现不同的还原降解速率和竞争还原态势并趋于稳定,降解反应符合一级反应动力学方程,降解速率由快到慢依次为PCB180、PCB138、PCB153、PCB52、PCB118、PCB101、PCB28,大体呈现氯原子数越多降解速率越快的趋势。试验条件下PCBs各异构体的降解半衰期为75-121 h。为从分子水平上分析不同含氯水平PCBs共存的竞争体系中PCBs还原降解速率的主要影响因素,采用高斯软件DFT方法求得7种多氯联苯的20个量子化学参数,通过偏最小二乘回归分析建立了PCBs的还原降解速率与分子结构的定量结构-性质关系模型。模型结果表明,Ehomo、△fH-Θ、△fG-Θ和Polar的VIP大于1,是影响体系中PCBs降解速率的主要因素。此模型可以较好地预测多氯联苯污染场地土壤化学修复过程中PCBs各同系污染物的化学降解潜力和残留趋势。
The given paper is aimed at presenting a few experimental results and a model of the degradation rate of polychlorinated biphenyls in the soils as well as the influential factors for the model building-up analysis.The results of our study indicate that the nickel-iron bimetal enjoys nice ability for the reductive degradation of PCBs,which proves that the different degradation rates and the reductive competitive situations with the increase of the reaction time,because the actual degradation reaction situation proves consistent with the first order of the reaction kinetic equation.The experimental reductive degradation rates in the descending order turn out to be in the following manner：PCB180 PCB138 PCB153 PCB52 PCB118 PCB101 PCB28 in the competitive reductive system.In addition,the degradation rates prove also to be generally correlated with the degree of chlorination of the halogenated organics.That is,the more in number the chlorine atoms,the faster the rate degrades.The half-life of PCBs isomers turns out to be 75-121 h under the experimental conditions.As regard to the major influential factors on the reductive degradation rates,we have worked out so far there are 20 quantum chemical descriptors with the density functional theory at B3LYP/6-31 G＊level,which proves to be characteristic with the different molecular structures and physicochemical properties of PCBs.Furthermore,we have also established a quantitative structure-property relationship model correlated with the reductive degradation properties of pollutants with their structural descriptors,which also helps us to establish an optimal model with the partial least squares analysis.Thus,it can be seen from the above model study that the VIP size of Ehomo,△fH~Θ,△fG~Θ and Polar should be greater than 1.They are actually the main influential factors that may affect the degradation rate of PCBs.Therefore,the above said optimal model has to be stable with very nice predictability,for which it can be adopted to be interpretable to account for the d
作者
丛鑫
朱含露
梅傲雪
张悦
CONG Xin;ZHU Han-lu;MEI Ao-xue;ZHANG Yue(College of Environmental Science and Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2018年第2期716-720,共5页
Journal of Safety and Environment
基金
国家自然科学基金项目(41403100)
关键词
环境学
镍铁双金属
土壤
多氯联苯
定量-结构性质关系
environmentalology
nickel iron bimetal
soil
poly- chlorinated biphenyls
quantitative structure-property relationship
