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Environmental problems on a global scale have become more prominent with the population growth. For the removal of organic contaminants, the solar energy and environmentally friendly photocatalysis are needed to substitute the fossil fuels. In this contribution, we report the synthesis, characterization and photocatalytic capability of CuAl2O4 nanoparticles. The spinel was elaborated by nitrate route and characterized physically and electrochemically for their correlations and application in photocatalysis through the degradation of Basic Red 46 (BR 46), a hazardous dye under visible illumination. The effects of several operational factors like the pH, catalyst dose and initial dye BR 46 concentration were optimized. The results revealed that the photocatalytic performance reached 93% at pH 10, 1 g/L of catalyst dose at a concentration of 10 mg/L of BR 46 within 120 min of irradiation. The quasi-total mineralization was confirmed by the total organic carbon (TOC) and dissolved organic carbon (DOC). Additionally, the prepared photocatalyst possesses a good cyclability with no significant change after five successive photocatalytic cycles. Furthermore, the radical scavenger tests revealed that the specie O2·− and the holes h+ have the significant effects on the removal of BR 46. Based on the latest results, a photocatalytic mechanism was proposed. [ABSTRACT FROM AUTHOR]

Nickel is a hazardous metal with a harmful effect on the health and environment. In this work, the photocatalytic reduction of Ni2+ was examined onto the hetero-system CoMn2O4/TiO2 under visible light irradiation. The spinel CoMn2O4 is prepared by co-precipitation and characterized in detail to correlate its structural, textural, morphological, compositional, optical and photoelectrochemical features. The effects of pH, catalyst dose and Ni2+ concentration were optimized. The Ni2+ reduction increased with decreasing both the catalyst dose and pH. The highest performance was obtained at pH 7.4, a catalyst dose of 1 g/L and Ni2+ concentration of 10 mg L−1 with a removal abatement of 88% after 180 min irradiation. The data were suitably fitted by the pseudo-first-order kinetic reaction with an apparent constant of 0.027 min−1. Besides, the durability and the stability of the hetero-system CoMn2O4/TiO2 were evaluated by four consecutive catalytic cycles. [ABSTRACT FROM AUTHOR]