Development And Application Of Passive Sampling Device For Water Based On Cyclodextrin Polymer Membranes

Concentration of chemicals in environment is indispensable data for the ecological risk assessment.Accurate measurement of the chemicals’ concentration can provide scientific basis for the environmental management and decision-making,thereby effectively preventing and controlling the environmental pollution.Due to the randomness,uncertainty and limitations of active sampling technology,in recent years,passive sampling technology has become a hot research topic.Thus,developing the passive sampling technology is of great significance for the distribution and migration of chemicals in environmental media.In this study,on the basis of the unique inclusion ability,cyclodextrins were selected as the matrix of functional material,and a clodextrin polymer membrane was prepared.Taking the cyclodextrin polymer membrane as the binding phase,a novel passive sampling device was developed,and futher be used for monitoring the chemicals’ concentration in water environment.The stability of host-guest complex is often quantified by the inclusion constant(K).In this study,a quantitative structure-property relationship(QSPR)model was developed based on stepwise multiple linear regression(MLR)analysis,which used K as the dependent variable and the Dragon descriptor of the guest molecule as an independent variable,to predict the inclusion ability of cyclodextrin to variety of chemicals.The model statistics parameters indicated that the established model had a good determination coefficient of 0.857,a high cross-validation coefficient of 0.835,a low root mean square error of 0.380,together with the acceptable results of external validation,which indicate a satisfactory goodness of fit,robustness and predictive ability of the model.Based on the screened eight descriptors,we propose an appropriate mechanism interpretation for the inclusion interaction.Additionally,the applicability domain of the current model was characterized by the Euclidean distance-based method and Williams plot,and results indicated that the model covered a large number of structurally diverse chemicals belonging to 13 different classes.Comparing with the previous reported models,this model has obvious advantages with a larger dataset,a higher value of correlation coefficient and a wider application domain.In recent years,due to the high detection rate of pharmaceuticals and personal care products(PPCPs)in the environmental medium,we selected triclosan(TCS),triclocarban(TCC)and methyl triclosan(MTCS)as the representative compounds,and further explored the inclusion ability of(3-cyclodextrin(β-CD)and hydroxypropyl-β-cyclodextrin(HP-β-CD)to the three compounds.The β-CD membrane and HP-β-CD membrane were prepared by phase inversion method and characterized by a series of means.Results indicated that both of them had good hydrophilicity and thermal stability.The adsorption dynamics results showed good adsorption properties of membranes for TCS,TCC and MTCS.The adsorption process followed the pseudo-second order model.The adsorption isotherms of TCS and TCC on membranes fitted into the Freundich and Langmuir model,while MTCS only fitted into the Freundich model.It shows that there are differences in adsorption mechanism between MTCS and the other two compounds,which maybe ascribed to the different inclusion ability of cyclodextrins to them.Based on the above study,a novel dynamic passive sampling device for water was developed with the cyclodextrin polymer membrane as binding phase,the agarose membrane as diffusion phase and the glass fiber membrane as protection phase.Optimal sampling parameters is a prerequisite for quantifing passive sampling data accurately.The sampling rates(Rs)were studied by experiment and theoretical calculation.Results showed that the data determined by different methods had a good consistency.The influence of ion effect and dissolved organic matter on the sampling rates was also investigated.In this case,we selected Jiuxiang River and Qinhuai River in Nanjing as the sampling sites,and deployed the sampling devices to verify the feasibility of the devices.Meanwhile,we collected the water samples at the sampling sites,and determined the compounds’ concentration by active sampling-solid phase extraction method.By comparison,there is no significant difference between the concentrations measured by passive sampling and active methods,which confirms the feasibility the passive sampler for monitoring the compounds’ concentration in natural waters.