30 Jul 2020

PUBLICATION NOTICE: High-Performance Photocatalytic Degradation of Model Contaminants with Iron Oxide–Based Colloidal Solutions under Broad-Spectrum Illumination

Abstract:  Small molecule contaminants, such as compounds from pharmaceuticals, personal care products, and pesticides, persist through traditional wastewater treatment processes. Heterogeneous photocatalysis with transition metal oxides (TMOs) is an emerging technology for removing these recalcitrant contaminants from wastewater. To leverage this technology, we selectively combined three different TMOs with bandgap energies in different regions of the solar spectrum as a means of harvesting multiple wavelengths of incident radiation to increase the degradation rate of model and real contaminants. Specifically, we combined zincite (ZnO, ultraviolet active), hematite (α-Fe2O3, visible active), and tenorite (CuO, near-infrared active). The combination of tenorite and hematite (2:1 mass ratio) was the most effective, degrading methyl orange with a rate constant of 40±1E-03 min−1. When applied to multicontaminant solutions using laboratory illumination, our multispectral photocatalyst degrades real-world contaminants, methyl orange, carbamazepine, and nitrobenzene, with rate constants of 30±1E-03, 24±1E-03, and 6±1E-03 min−1, respectively. In addition, the material degrades contaminants with a greater efficiency under outdoor solar illumination, with Collector Area per Order values of 4.0, 6.1 and 14.5 kWh/order/m³, for methyl orange, carbamazepine, and nitrobenzene, respectively. These results demonstrate the effectiveness of this approach to purify water for strategic applications.