Ultrasound-assisted gadolinium-doped manganese oxide nanocatalyst and the investigation of Catalytic properties

Degradation of hazardous organic pollutants existing in industrial wastewater via advanced oxidation processes (AOPs) has been an active area of research [1, 2]. Gadolinium (Gd3+)-substituted nanocrystalline Mn2O3 (Mn2-xGdxO3) was obtained by oxidation of Mn(NO3)2 at ambient conditions under ultrasound sonication in basic solution. Gd3+ substitution into the structure of Mn2O3 resulted in a material with new physical properties, composition, and morphology. The SEM, XRD, EDX, TEM, HRTEM, XPS techniques were used for characterization of as-prepared material. Increasing the amount of Gd3+ ions during synthesis did not increase significantly the percent substitution in the final product beyond 6%. The influence of substitution of Gd3+ ions into Mn2O3 caused a red shift in the absorbance and a decrease in the band gap. The as-synthesized compounds were used for photocatalytic degradation of Methylene Blue (MB). 6% Gd-doped Mn2O3 displayed the elevated photocatalytic activity considering various amounts of gadolinium. The order of inhibitory effect of radical scavengers was 1, 4 Benzoquinone ˃ SO32− ˃ t-BuOH ˃ I− ˃ C2O42-. The influence of various specifications like catalyst amount, initial dye concentration, and ultrasonic power was explored.