Preparation of CaAlGa and ZnAlTi mixed metal oxides (MMO) synthesized via CaAlGa–hydrocalumites and ZnAl–hydrotalcite impregnated with TiO2 using saline slags as aluminum source, is reported for the first time. The solids obtained by calcination at 750 ºC are highly crystalline and the photocatalytically active crystalline phases Ca12Al14-xGaxO33, ZnO, ZnAl2O4 and Zn2TiO4 have been identified. The MMO were used for the catalytic degradation of paracetamol under UV irradiation, obtaining good results for the removal of this emerging pollutant, reaching a removal above 90 % for the sample containing 25 % Ga3 +, under the optimum photodegradation conditions ([Paracetamol]0 = 40 mg/L and catalyst dose = 1 g/L), showing better results than the commercial photocatalyst TiO2–P25 from Degussa and other more complex catalysts based on MMO. In addition, this photocatalyst was submitted to a cyclic process study, finding that it maintained its performance after at least two cycles.

This research was funded by Spanish Ministry of Science, Innovation and Universities through Spanish Research Agency (Reference PID2023-146935OB-C21 and PID2023-146935OB-C22). AG is also grateful for financial support from the Spanish Ministry of Science and Innovation (MCIN/AEI/10.13039/501100011033) through project PID2020-112656RB-C21.