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 (CuAl2O4 and ZnAl2O4) was evaluated. Chemical and physical properties were considered, and ZnAl2O4 showed higher RhB degradation efficiency (73.90% in only 10 min) than CuAl2O4 (51.95% in 10 min), reaching up to 100% in 30 min. According to results, a further RhB catalytic degradation pathway by ZnAl2O4 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 ZnAl2O4 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 ZnAl2O4 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(center dot-) and h(+). Thus, ZnAl2O4 proved to be an efficient photocatalyst for quick RhB pollutant degradation with promising potential for real wastewater treatment applications. (c) 2019 Society of Chemical Industry