QSAR Study On Diffusion Coefficient Of Typical Organic Pollutants In LDPE

In recent years,passive sampling technology has been widely used in the monitoring of trace organic pollutants in water.In the passive sampling technology of water body,the molecular diffusion coefficient is an important parameter to calculate the concentration of target compounds in water body through the dynamic diffusion control method,and it is also one of the very important quantitative parameters to describe the toxic effect of hydrophobic organic pollutants.Because most of the diffusion coefficients of pollutants need to be obtained by tedious experimental measurements,and the relevant experimental data are far from meeting the needs of the growing monitoring of organic pollutants,it is necessary to develop a more simple,efficient and accurate prediction model to quantitatively predict the diffusion coefficients.Based on the pp-LFER model and PaDEL descriptors,the prediction model of diffusion coefficient of organic pollutants in LDPE was built according to the guidelines of QSAR construction and validation issued by OECD.The main contents and results are as follows:The experimental values of diffusion coefficients of 120 typical organic pollutants on LDPE membrane were collected and sorted out by referring to relevant literature,covering five different chemical categories,including polycyclic aromatic hydrocarbons,polychlorinated biphenyls,organochlorine pesticides,new pollutants and polybrominated diphenyl ethers.Based on the pp-LFER model,the prediction model is established by stepwise multiple linear regression.The model was validated,characterized,applied domain analyzed and mechanism explained.The pp-LFER model has good goodness of fit(Radj2=0.815)and robustness(QLOO2 and QBOOT2 of 0.776 and 0,791,respectively).It can predict a variety of typical organic pollutants including polycyclic aromatic hydrocarbons,polychlorinated biphenyls,organochlorine pesticides,new pollutants and polybrominated diphenyl ethers.The model shows that in the diffusion process of polymer structure,the compounds with smaller molecular volume are easier to diffuse than those with larger molecular volume,and the diffusion coefficient and mass transfer coefficient are larger,which may be due to the less energy required for the formation of holes in the polymer by the target molecules with smaller volume.In order to further improve the statistical index of the model,an optimal QSAR model with five molecular descriptors(ETA Alpha,ASP-6,IC1,TDB6r and ATSC2v)was constructed based on padel descriptors.The goodness of fit(Radj2)is 0.949,the robustness(QLOO2)and the robustness(QBOOT2)are 0.941 and 0.784,respectively.Among them,ETA_Alpha is the most important factor affecting the diffusion coefficient of organic pollutants on LDPE.In addition,molecular volume,hydrophobic interaction,topological path and distance,van der Waals volume and other factors are conducive to the diffusion behavior of HOCs in LDPE.Compared with the previous studies,the two QSAR model developed in this study has more kinds and quantities of selected compounds,and the molecular structure parameters can be obtained by calculation,independent of experimental determination.In addition,the model established in this study is validated and characterized in application domain,and the mechanism is explained.The statistical parameters of these two models have good performance in goodness of fit,robustness and prediction ability.Therefore,the proposed model can be used to predict the applicability of other compounds?...