Preparation of Bi2MoO6@Diatomite composite and its visible light driven reduction of Cr(VI) and removal of tetracycline hydrochloride

Abstract

The use of cheap and porous substrates to support visible light photocatalyst is an effective solution to avoid the agglomeration of catalyst. Herein, the Bi2MoO6@Diatomite composite has been prepared through hydrothermal reaction with Bi(NO3)3 and Na2MoO4 as precursors and diatomite as substrate. XRD, SEM, TEM, XPS, and DRS are applied to characterize these composite photocatalysts. The photocatalytic performance of the obtained composites were studied through the Cr(VI) reduction and tetracycline hydrochloride (TC) degradation under visible light irradiation (λ > 400 nm). The photocatalytic experimental results display that the sample with 6% diatomite mass faction (Bi2MoO6@6%DE) has the highest catalytic performance in all materials. In the Cr(VI) solution, the Bi2MoO6@6%DE can reduce 90.1% of Cr(VI) in 60 min, while Bi2MoO6 can only reduce 71.7% of pollutants in the same time. In the TC solution, the Bi2MoO6@6%DE can reduce 74.7% of TC in 120 min, while Bi2MoO6 can only reduce 30.5% of pollutants in the same time. The photocatalytic mechanism was further investigated through the test of active radical capture. The main active radicals in the reduction of Cr(VI) is photogenerated electrons. The •HO-, •O2- and holes (h+) are active free radicals in the removal process of TC, and photogenerated holes (h+) have the greatest influence. This composite has good photocatalytic activity and recyclability, so it has great application potential in waste water treatment.