Removal of arsenic with reduced graphene oxide-TiO2-enabled nanofibrous mats

Camrynn L. Fausey, Ines Zucker, Evyatar Shaulsky, Julie B. Zimmerman, Menachem Elimelech

Research output: Contribution to journalArticlepeer-review

Abstract

Arsenic contamination is found at dangerous levels in drinking water around the world and is many times treated with an oxidation step from arsenite [As(III)] to the more easily adsorbed and less toxic arsenate [As(V)]. Herein, electrospun nanofibrous mats made of poly(lactic-co-glycolic) acid and chitosan are coated with reduced graphene oxide (rGO) and titanium dioxide (TiO2) for enhanced oxidation of arsenic. We compared the oxidative properties of UV-irradiated rGO-TiO2 nanocomposite-enabled fibers (rGO-TiO2@fibers) to both their non-reduced counterpart (GO-TiO2@fibers) and TiO2 nanoparticles in suspension. The rGO-TiO2@fibers have a rate constant an order of magnitude larger, and oxidize 2.5 times more As(III), per mass of TiO2 as compared to GO-TiO2@fibers. When bound to UV-illuminated TiO2, GO—and especially the more-conductive rGO—accept electrons from TiO2’s valence band, inhibiting electron-hole recombination and increasing production of hydroxyl radicals (⋅OH) that oxidize As(III). Hydroxyl radical generation was correlated with As(III) oxidation and used to determine radical-scavenging of the fibers. TiO2 paired with rGO achieved the highest levels of radical production both when bound to fibers and when in suspension, illustrating a synergistic relationship between rGO and TiO2. Reuse properties and titanium leaching of the rGO-TiO2@fibers and GO-TiO2@fibers were evaluated over the course of six oxidative cycles, illustrating limited leaching and consistent enhanced oxidative performance by the rGO-TiO2@fibers. Nanocomposites of rGO-TiO2 have not yet been reported as a surface coating on electrospun fibrous scaffolds, and their applications are typically in dye degradation, bacteria inactivation, and electrochemistry. Through their superior oxidative performance, “green” synthesis, and facile recyclability, rGO-TiO2@fibers herein are an example of nano-enabled technology being strategically leveraged to address water treatment challenges around the world.

Original languageEnglish
Article number122040
JournalChemical Engineering Journal
Volume375
DOIs
StatePublished - 1 Nov 2019

Keywords

  • Arsenic removal
  • Electrospinning
  • Nanofibers
  • Reduced graphene oxide
  • Titanium dioxide

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