Photoremediation of heavy metals from aqueous environments onto ZnO coated fibrous polyethylene terephthalate nonwovens

Abstract

This work explores the photoremediation of hexavalent chromium from aqueous solutions on to nonwoven polyethylene terephthalate substrates modified by nanoscale atomic layer deposition coatings of ZnO. Removal of Cr6+ is observed to increase with ZnO thin film thickness up to 500 atomic layer deposition cycles (∼90 nm) with a maximum Cr6+ removal of 67% after an exposure of 540 J/cm2. Instead of reducing Cr6+ to Cr3+, this work shows that the mechanism for removal of the Cr ion from solution is by sorption and photoreduction of the metal onto the ZnO surface. Additionally, mixed solutions with Cr6+ and As3+ ions were tested for simultaneous photoreduction and photooxidation, showing that mixed ion solutions may better utilize photogenerated electrons and holes, simultaneously. The reported demonstration and analysis represents a facile route for reclamation of toxic components in an aqueous media.This work explores the photoremediation of hexavalent chromium from aqueous solutions on to nonwoven polyethylene terephthalate substrates modified by nanoscale atomic layer deposition coatings of ZnO. Removal of Cr6+ is observed to increase with ZnO thin film thickness up to 500 atomic layer deposition cycles (∼90 nm) with a maximum Cr6+ removal of 67% after an exposure of 540 J/cm2. Instead of reducing Cr6+ to Cr3+, this work shows that the mechanism for removal of the Cr ion from solution is by sorption and photoreduction of the metal onto the ZnO surface. Additionally, mixed solutions with Cr6+ and As3+ ions were tested for simultaneous photoreduction and photooxidation, showing that mixed ion solutions may better utilize photogenerated electrons and holes, simultaneously. The reported demonstration and analysis represents a facile route for reclamation of toxic components in an aqueous media.