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/m 3 , for methyl orange, carbamazepine, and nitrobenzene, respectively. These results demonstrate the effectiveness of this approach to purify water for strategic applications. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

Photocatalytic Degradation of Polycyclic Aromatic Hydrocarbons in Water by 3D Printed TiO2 Composites

“…One of the most practical approaches to improve photocatalytic efficacy is extending the activity of the catalyst in the visible light region. 5 Notably, there are numerous TiO 2 modifications with improved photocatalytic degradation under visible light, including Ti/ ZnO composites; 48,49 Ti/ZnO-Cr 2 O 3 ; 50 Cu/N-doped TiO 2 nanoparticles; 51 and TiO 2 -graphene composites. 52 Additionally, there may be added benefits of modifying the catalyst through other mechanisms including inhibition of recombination of election−hole pairs and charge separation capabilities.…”

“…One of the most practical approaches to improve photocatalytic efficacy is extending the activity of the catalyst in the visible light region . Notably, there are numerous TiO 2 modifications with improved photocatalytic degradation under visible light, including Ti/ZnO composites; , Ti/ZnO-Cr 2 O 3 ; Cu/N-doped TiO 2 nanoparticles; and TiO 2 -graphene composites . Additionally, there may be added benefits of modifying the catalyst through other mechanisms including inhibition of recombination of election–hole pairs and charge separation capabilities. , The proof of concept that TiO 2 can be immobilized in 3D printable polymer to enable rapid and customizable geometries provides an exciting prototyping opportunity for iterative research process improvements (e.g., in-line UV systems; bench- and mesocosm-scale toxicity identification and reduction evaluations) to evaluate photocatalytic performance in this rapidly evolving field of research.…”