Photocatalytic Activity of Magnesium Aluminate for Degradation of Petroleum Waste on Water Surface Driven by Sunlight.

MgAl₂O₄ nanoparticles with high photocatalytic activity simulated by sunlight were synthesized by polyacrylamide gel method using maltose and sucrose as anti-gel collapsing agents. Spinel type MgAl₂O₄ nanoparticles without impurities such as MgO, Al₂O₃, Mg(OH)₂, and Al(OH)₃ can be synthesized by two different methods. Fourier infrared spectroscopy shows that the characteristic peaks of 698 and 506 cm^–1 can be attributed to the O–Mg and Al–O bonds in MgAl₂O₄. The surface morphology, optical absorption coefficient, optical band gap value and photocatalytic activity of MgAl₂O₄ nanoparticles can be effectively adjusted by anti-gel collapsing agent. The results show that the MgAl₂O₄ nanoparticles prepared by maltose are obviously agglomerated, but the MgAl₂O₄ nanoparticles prepared by sucrose are uniformly dispersed, and the average particle size is about 45 nm. The photocatalytic activity of MgAl₂O₄ nanoparticles was positively correlated with the optical absorption coefficient during the degradation of petroleum waste on water surface. The optical properties of MgAl₂O₄ nanoparticles synthesized with maltose and sucrose as anti-gel collapsing agents showed that the optical band gap values were 3.47 and 3.11 eV, respectively. Meanwhile, the phase structure, functional group information, microstructure and optical properties of MgAl₂O₄ nanoparticles loaded on the drift beads were also compared and explored. The MgAl₂O₄ nanoparticles prepared with sucrose as gel collapsing agent and loaded on the drift bead have high visible photocatalytic activity and cycling stability when degrading oil waste on water surface, and the optimal catalyst content is 2 g/L. Combined with the experimental results and energy band theory, hydroxyl radical and superoxide radical play important roles in the degradation of oil waste on water surface by MgAl₂O₄ nanoparticles. [ABSTRACT FROM AUTHOR]