Nano spinel NiAl₂O₄: structure, optical and photocatalytic performance evaluation and optimization

Abstract

Four kinds of spinel NiAl2O4 were synthesized by the polyacrylamide gel method using Al2(SO4)3·18H2O and Al(NO3)3·9H2O as aluminum salts and anhydrous NiSO4 and NiSO4·6H2O as nickel salts. The effects of different aluminum salts and nickel salts on the structure, optical and photocatalytic activity of spinel NiAl2O4 were confirmed by various characterizations. There is no NiO impurity in the spinel NiAl2O4 synthesized with Al2(SO4)3·18H2O as aluminum salt, while NiAl2O4, NiO and C–O functional group coexist in the target product with Al(NO3)3·9H2O as aluminum salt, and C–O functional group and NiO inhibits the photocatalytic activity of the system. Based on photocatalytic experiment, response surface methodology and free radical verification experiment, the influence of experimental parameters including synthesis pathway, initial drug concentration, initial pH and catalyst content on the photocatalytic activity of spinel NiAl2O4 and the main active species involved in the reaction were investigated. The degradation percentage of spinel NiAl2O4 synthesized with Al2(SO4)3·18H2O as aluminum salt and NiSO4·6H2O as nickel salt was 86.3% at the initial concentration of 50 mg l−1, pH = 5.33 and catalyst content of 1 g l−1. The mechanism investigation confirmed that the C–O functional group plays the dual role of impurity level and electron transfer in the degradation of tetracycline hydrochloride by spinel NiAl2O4.

A novel CuAl2O4/MoS2/BaFe12O19 magnetic photocatalyst simultaneously coupling type I and Z-scheme heterojunctions for the sunlight-driven removal of tetracycline hydrochloride

“…It is worth noting that after EDTA-2Na is introduced into the reaction solution, it can capture h + and ·OH, but it is difficult to capture ·O 2 − because it shows a certain photocatalytic activity due to the role of ·O 2 − . 88–91 Similar results were obtained for IPA and BQ. Therefore, it is insufficient to determine the role of each free radical in the photocatalysis process through only the capture experiment.…”