Polymeric Nanofiber-Carbon Nanotube Composite Mats as Fast-Equilibrium Passive Samplers for Polar Organic Contaminants

• Published in: Environmental science & technology 2020-06, Vol.54 (11), p.6703-6712
• Main Authors: Qian, Jiajie, Martinez, Andres, Marek, Rachel F, Nagorzanski, Matthew R, Zhi, Hui, Furlong, Edward T, Kolpin, Dana W, LeFevre, Gregory H, Cwiertny, David M
• Format: Article
• Language: English
• Subjects: Atrazine; Contaminants; Electrons; Equilibrium; Herbicides; Hydrophobicity; Mats; Multi wall carbon nanotubes; Nanofibers; Nanotechnology; Nanotubes; Organic contaminants; Performance enhancement; Polyacrylonitrile; Polymers; Polystyrene; Polystyrene resins; Samplers; Sampling; Surface water
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.0c00609

To improve the performance of polymeric electrospun nanofiber mats (ENMs) for equilibrium passive sampling applications in water, we integrated two types of multiwalled carbon nanotubes (CNTs; with and without surface carboxyl groups) into polyacrylonitrile (PAN) and polystyrene (PS) ENMs. For 11 polar and moderately hydrophobic compounds (-0.07 ≤ log ≤ 3.13), 90% of equilibrium uptake was achieved in under 0.8 days ( values) in nonmixed ENM-CNT systems. Sorption capacity of ENM-CNTs was between 2- and 50-fold greater than pure polymer ENMs, with equilibrium partition coefficients ( values) ranging from 1.4 to 3.1 log units (L/kg) depending on polymer type (hydrophilic PAN or hydrophobic PS), CNT loading (i.e., values increased with weight percent (wt %) of CNTs), and CNT type (i.e., greater uptake with carboxylated CNTs composites). During field deployment at Muddy Creek in North Liberty, Iowa, optimal ENM-CNTs (PAN with 20 wt % carboxylated CNTs) yielded atrazine concentrations in surface water with a 40% difference relative to analysis of a same-day grab sample. We also observed a mean percent difference of 30 (±20)% when comparing ENM-CNT sampler results to grab sample data collected within 1 week of deployment. With their rapid, high capacity uptake and small material footprint, ENM-CNT equilibrium passive samplers represent a promising alternative to complement traditional integrative passive samplers while offering convenience over large volume grab sampling.