The application of molecularly imprinted polymers in passive sampling for selective sampling perfluorooctanesulfonic acid and perfluorooctanoic acid in water environment

Abstract

Modeling and predicting of a novel polar organic chemical integrative sampler (POCIS) for sampling of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) using molecularly imprinted polymers (MIPs) as receiving phase are presented in this study. Laboratory microcosm experiments were conducted to investigate the uptake kinetics, effects of flow velocity, pH, and dissolved organic matter (DOM), and also the selectivity of the POCIS. In this study, uptake study of PFOA and PFOS sampling on MIP-POCIS, over 14 days, was investigated. Laboratory calibrations of MIP-POCIS yielded sampling rate (R_s) values for PFOA and PFOS were 0.387 and 0.229 L/d, higher than POCIS using commercial sorbent WAX as receiving phase (0.133 and 0.141 L/d for PFOA and PFOS, respectively) in quiescent condition. The R_s values for PFOA and PFOS sampling on MIP-POCIS were increased to 0.591 and 0.281 L/d in stirred condition (0.01 m/s), and no significant increase occurred when the flow velocity was further increased. The R_s values were kept relatively high in the solution of which the pH was lower than the isoelectric point (IEP) of MIP-sorbent and decreased when the solution pH was extend the IEP value. Under the experimental conditions, DOM seemed to slightly facilitate the R_s values of PFOA and PFOS in MIP-POCIS. The results showed that the interaction between the target compounds and the receiving phase was fully integrated by the imprinting effects and also the electrostatic interaction. Finally, comparing the sampling rate of WAX-POCIS and the MIP-POCIS, the MIP-POCIS offers promising perspectives for selective sampling ability for PFOA and PFOS.

Keywords: Molecularly imprinted polymers; POCIS; Sampling rate; Selective sampling; Typical perfluoroalkyl substance.