Cobalt aluminates prepared by ultrasonic-assisted synthesis using different surfactants for Congo red photocatalytic degradation

Abstract Bright blue cobalt aluminate powders were prepared using ultrasonic-assisted co-precipitation and hydrothermal methods. In addition, triethylamine (TEA), butyrolactam (BL), and n-cetyl-n,n,n-trimethylammonium bromide (CTAB) surfactants were used during synthesis to enhance the sample characteristics. The prepared compounds were compared based on their photocatalytic characteristics and the degradation of Congo Red (CR). From X-ray diffraction, the synthesised compounds were identified as CoAl 2 O 4 with a spinel structure. Scanning electron microscopy revealed that polygonal particles were obtained in the ultrasonic-assisted co-precipitation method whereas rounded particles were obtained in the ultrasonic-assisted hydrothermal method. The most homogeneous morphology was seen in the co-precipitation sample using TEA, and the smallest particles were observed in the hydrothermal samples using BL. The highest CR removal was achieved in the co-precipitation and hydrothermal samples prepared using TEA, with 46.15 % and 39 % removal, respectively. The determination of the optimal experimental parameters was effective in enhancing the photocatalytic properties of spinel CoAl 2 O 4 .