Efficient detoxication of heterocyclics by layered double hydroxides contained different cobalt components as photocatalysts based on controllable application of active free radicals

Abstract In this paper, we synthesized a series of novel layered double hydroxides (LDHs) based materials with three types of different organic/inorganic cobalt components (Co 3 O/CoCr 1 –Co 2 /SB–LDHs). The Co components were distributed in the layers (Co 1 ), intercalated between the layers (Co 2 ) and combined on the surface of the material (Co 3 ), collectively. The composition of each Co species was adjusted to reveal the connection between different modifications and their photocatalytic activity and mechanism towards two heterocyclic compounds (pyridine and thiophene) degradation reaction. The photocatalytic experimental results showed that photodegradation of heterocyclics varies due to different Co components, the catalyst with moderate Co contents has the highest degradation rate of 90.6% for pyridine and 96.5% for thiophene. The free radical test indicated that Co 1 components determine the production of O 2 – radicals, Co 2 species determine the generation of OH radicals, and Co 3 elements are responsible for the production of OOH radicals. Moreover, we also found that during the photocatalytic oxidation of heterocyclic compounds, the contribution of three radicals follows the order that OH radical > O 2 – radical > OOH radical. Thus, we can fabricate this type of layered double hydroxides with different cobalt components to implement the controllable utilization of active free radicals during the photo oxidation. In addition, the photoreaction mechanism, intermediates and degradation pathway of heterocyclics were also investigated in detail.