Reactive oxygen species‐induced heterogeneous photocatalytic degradation of organic pollutant Rhodamine B by copper and zinc aluminate spinels

Abstract BACKGROUND The importance of potable water is immeasurable and its contamination by pollutants is a serious environmental problem. Rhodamine B (RhB), one such pollutant, is highly toxic to various organisms and may cause long‐term undesirable effects when improperly disposed of. Thus, development of an efficient treatment technique is necessary. Among the new oxidation methods, heterogeneous photocatalysis is an emerging pollutant destructive technology. RESULTS The photocatalytic activities of copper (Cu) and zinc (Zn) aluminate spinels (CuAl 2 O 4 and ZnAl 2 O 4 ) was evaluated. Chemical and physical properties were considered, and ZnAl 2 O 4 showed higher RhB degradation efficiency (73.90% in only 10 min) than CuAl 2 O 4 (51.95% in 10 min), reaching up to 100% in 30 min. According to results, a further RhB catalytic degradation pathway by ZnAl 2 O 4 was monitored by UV‐visible spectrometry and ultra‐high performance liquid chromatography coupled to diode array detection (UHPLC‐DAD) analysis. When applied to wastewater from gemstone beneficiation, containing elevated RhB concentration, the ZnAl 2 O 4 caused 88% color removal in 120 min and its pollutant removal rate was 18 times greater than the commonly used ZnO. CONCLUSION The superior performance of ZnAl 2 O 4 can be attributed to better pore properties, responsible for providing more active sites. These identified reactive oxygen species (ROS)‐induced interactions and the species demonstrated that degradation occurs due to generation of O 2 •‐ and h + . Thus, ZnAl 2 O 4 proved to be an efficient photocatalyst for quick RhB pollutant degradation with promising potential for real wastewater treatment applications. © 2019 Society of Chemical Industry