Synthesis, Optimization, and Performance Demonstration of Electrospun Carbon Nanofiber-Carbon Nanotube Composite Sorbents for Point-of-Use Water Treatment.
We developed an electrospun carbon nanofiber-carbon nanotube (CNF-CNT) composite with optimal sorption capacity and material strength for point-of-use (POU) water treatment. Synthesis variables including integration of multiwalled carbon nanotubes (CNTs) and macroporosity (via sublimation of phthalic acid), relative humidity (20 and 40%), and stabilization temperature (250 and 280 °C) were used to control nanofiber diameter and surface area (from electron microscopy and BET isotherms, respectively), surface composition (from XPS), and strength (from AFM nanoindentation and tensile strength tests). Composites were then evaluated using kinetic, isotherm, and pH-edge sorption experiments with sulfamethoxazole (log Kow = 0.89) and atrazine (log Kow = 2.61), representative micropollutants chosen for their different polarities. Although CNFs alone were poor sorbents, integration of CNTs and macroporosity achieved uptake comparable to granular activated carbon. Through reactivity comparisons with CNT dispersions, we propose that increasing macroporosity exposes the embedded CNTs, thereby enabling their role as the primary sorbent in nanofiber composites. Because the highest capacity sorbents lacked sufficient strength, our optimal formulation (polyacrylonitrile 8 wt %, CNT 2 wt %, phthalic acid 2.4 wt %; 40% relative humidity; 280 °C stabilization) represents a compromise between strength and performance. This optimized sorbent was tested with a mixture of ten organic micropollutants at environmentally relevant concentrations in a gravity-fed, flow-through filtration system, where removal trends suggest that both hydrophobic and specific binding interactions contribute to micropollutant uptake. Collectively, this work highlights the promise of CNF-CNT filters (e.g., mechanical strength, ability to harness CNT sorption capacity), while also prioritizing areas for future research and development (e.g., improved removal of highly polar micropollutants, sensitivity to interfering cosolutes).
Department of Civil and Environmental Engineering, University of Iowa , Iowa City, Iowa 52242, United States.
Katherine T
KT
Peter
State Hygienic Laboratory, University of Iowa , Iowa City, Iowa 52242, United States.
John D
JD
Vargo
Department of Chemistry, University of Iowa , Iowa City, Iowa 52242, United States.
Thilini P
TP
Rupasinghe
Department of Biomedical Engineering, University of Iowa , Iowa City, Iowa 52242, United States.
Aribet
A
De Jesus
Department of Chemistry, University of Iowa , Iowa City, Iowa 52242, United States.
Alexei V
AV
Tivanski
Department of Biomedical Engineering, University of Iowa , Iowa City, Iowa 52242, United States.
Edward A
EA
Sander
Department of Chemical and Environmental Engineering, University of California , Riverside, California 92521, United States.
Nosang V
NV
Myung
Department of Civil and Environmental Engineering, University of Iowa , Iowa City, Iowa 52242, United States.
David M
DM
Cwiertny
D002606:Charcoal; D005374:Filtration; D057139:Nanofibers; D037742:Nanotubes, Carbon; D018508:Water Purification
D037742:Nanotubes, Carbon; D002606:Charcoal
carbonaceous nanomaterials; electrospinning; emerging pollutants; environmental nanotechnology; point of use; water treatment