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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. CONCLUSIONBoth Cu and Zn aluminate spinels presented elevated catalytic performance, but when compared, ZnAl 2 O 4 presented higher J Chem Technol Biotechnol 2020; 95: 791-797

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The objective of this work was to evaluate the degradation of rhodamine B dye from aqueous solution by photo-Fenton reaction under visible irradiation using a Fe-rich bentonite as a catalyst. The material was thermally treated at a low temperature (200 °C) and characterized by XRD, N 2 adsorption-desorption isotherms, FTIR, SEM-EDS and XRF. Iron leaching in aqueous solution after the photo-Fenton reaction was evaluated by atomic absorption spectroscopy. The material exhibited a mesoporous structure, containing a specific surface area of 99 m 2 .g -1 . The catalytic results showed significant dye degradation, reaching 95% of decolorization and 72% of mineralization at 300 min of reaction. The catalyst showed high chemical stability in four reaction cycles. Therefore, this thermally treated Fe-rich bentonite can be considered as a promising catalyst in the heterogeneous photo-Fenton reaction for the degradation of rhodamine B from aqueous solution. ResumoO objetivo deste trabalho foi avaliar a degradação do corante rodamina B em solução aquosa por reação foto-Fenton sob irradiação visível utilizando uma bentonita rica em ferro como catalisador. O material foi tratado termicamente a baixa temperatura (200 ºC) e caracterizado por DRX, isotermas de adsorção-dessorção de N 2 , FTIR, MEV-EDS e FRX. A lixiviação do ferro na solução aquosa após a reação foto-Fenton foi avaliada por espectroscopia de absorção atômica. O material exibiu uma estrutura mesoporosa, apresentando uma área de superfície específica de 99 m 2 .g -1 . Os resultados catalíticos mostraram alta eficiência na degradação do corante, atingindo 95% de descoloração e 72% de mineralização em 300 min de reação. O catalisador apresentou alta estabilidade química em quatro ciclos de reação. Portanto, esta bentonita rica em Fe tratada termicamente pode ser considerada como um promissor catalisador na reação foto-Fenton heterogênea para a degradação da rodamina B em solução aquosa.