Bi2MoO6 microspheres for the degradation of orange II by heterogeneous activation of persulfate under visible light

The 3D microspheres of Bi2MoO6 samples were synthesized hydrothermally using different Bi:Mo molar ratios and evaluated for the removal of orange II under visible light by activating with K2S2O8. The Bi-Mo-2 sample (Bi:Mo molar ratio of 2:1, i.e., stoichiometric composition of Bi2MoO6) showed the strongest catalytic activity by removing 99.43% orange II within 120 min among the several different Bi-Mo materials. The surface of the microspheres was composed of irregular nanosheets with exposed reactive sites, which are beneficial for degrading orange II. Moreover, the Bi2MoO6 catalyst demonstrated good cycling stability and could be reused for at least five runs with only a 6.99% decrease in degradation. The proposed mechanism of photocatalytic activity could be explained by the generation of superoxide radical O-2 center dot along with SO4 center dot and OH center dot radicals, which were found to be responsible for the orange II degradation. Our research led to an efficient and stable photochemical catalyst for orange II dye degradation in wastewater. (C) 2019 Elsevier B.V. All rights reserved.