Preparation, characterisation, and growth mechanism of mesoporous petal-like MgAl2O4 spinel

Abstract

Petal-like MgAl2O4 spinel was successfully prepared using a novel inorganic salt-assisted nonhydrolytic sol-gel method without a template and was employed as absorbent in the removal of the Congo red (CR). The effects of the inorganic salt type, heat-treatment temperature, and dwelling time on the morphology and phase composition of the petal-like MgAl2O4 spinel were investigated systematically. Results indicated that when Na2MoO4 was employed as the salt and the heat-treatment temperature and dwelling time were 600 °C and 5 h, respectively, the as-obtained petal-like MgAl2O4 spinel exhibited a highly uniform morphology with a thickness of 19–23 nm and a length of 240–280 nm. The N2 adsorption-desorption results revealed that the petal-like MgAl2O4 exhibited a large BET specific surface area of 161 m2g-1 with a pore volume of 0.24 cm3g-1. The growth mechanism of the petal-like MgAl2O4 is believed to be the formation of a two-dimensional layered network structure by the coordination between the condensation product of the magnesium aluminium bimetallic alkoxides and the ions in the salt. The as-prepared MgAl2O4 petal exhibited an effective adsorption capacity toward anionic dyes CR. The maximum adsorption capacity of CR onto the mesoporous MgAl2O4 petal was found to be 572.01 mg/g, it is showed the petal-like MgAl2O4 exhibit huge potential of application in the field of environmental remediation.