Pesticide contamination of surface waters is a critical concern for potential impacts on the ecosystem and drinking water supplies. Current passive sampling techniques, like POCIS, often need deployment times around 4-6 weeks, and may not be well-suited for analysis of small, polar organic contaminants and charged species. Here, we fabricated electrospun polymer nanofiber mats, or ENMs, with embedded carbon nanotubes for use as fast-equilibrating passive sampling materials. Using polyacrylonitrile (PAN) with embedded carboxylated carbon nanotubes, we show that these composite ENMs can quickly achieve equilibrium with a range of organic chemicals, including common pesticides. Moreover, through rapid, reversible uptake, ENMs are responsive to temporal changes in dissolved pollutant concentrations that occur over short timescales compared to more traditional passive samplers. The extent of pollutant uptake can also be tuned through integration of additional species into the ENMs including surface-segregating surfactants and the use of porogens to increase pore volume and specific surface area. Ongoing work includes field performance validation, where ENMs are being deployed in an agriculturally impacted creek over short timescales (1-2 h) to study temporal trends in the concentration of atrazine and other widely used pesticides. Results from ENMs are being compared to corresponding grab samples collected across the deployment period. Ultimately, these materials represent a promising passive sampling technology that complements existing approaches for its ability to capture shorter temporal trends and tighter spatial resolution.

Using electrospun polymer nanofiber-carbon nanotube composites as equilibrium passive samplers to study temporal trends in Atrazine surface water concentrations

ACS Spring 2022

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