Efficient microwave enhanced degradation of 4-nitrophenol in water over coupled nickel oxide and solid acid catalysts

Abstract

An efficient and controllable abatement of 4-nitrophenol based on series of catalysts and auxiliary reagents, the as-prepared nickel oxide and solid acid tabloid, was reported as resulting by microwave degradation. In regard to the effects of microwave power, various kinds of nickel oxide and solid acid, at auxiliary reagent dosage, and in various concentrations were evaluated in relation to their removal efficiency. The results showed that the addition of solid acid can delicately tune the reaction pH and enhance the degradation of 4-nitrophenol over nickel oxide. The performance was apparently affected according to the kinds of solid acid and the as-prepared nickel oxide. The reducibility and amount of high valence of Ni3+ over the as-prepared NiOx can influence the resultant reaction. The lower reduction temperature and higher NH2/NNi ratio can weaken the bond strength of NiOx and readily releases partial oxygen to assist with the degradation of 4-NP within a microwave system. Both 300 and 500 ppm 4-nitrophenol can be completely degraded within 25 min under low power of 7 W over 0.12 g of as-prepared nickel oxide coupled with 0.24 g zirconium sulfate tabloid to adjust the reaction pH below 3 via the combined effect of nickel oxide and solid acid.