Efficient degradation of lomefloxacin by Co-Cu-LDH activating peroxymonosulfate process: Optimization, dynamics, degradation pathway and mechanism

Abstract

In this study, bimetal layered double hydroxides (Co_xCu_y-LDHs) containing a carbonate interlayer were synthesized using coprecipitation with a variety of Co/Cu mole ratios. Meanwhile, the corresponding layered double oxides (Co_xCu_y-LDOs) were prepared as controls. In this study, Electrical energy per order was performed to evaluate economic analysis. Correspondingly, we found that Co_xCu_y-LDHs possessed a significantly better PMS activation capability than the corresponding metal oxide composite (Co₃O₄/CuO). Compared with other Co_xCu_y-LDHs, Co₂Cu₁ LDH possessed the best PMS activation capability for LOM degradation and the lowest electrical energy per order (EE/O) value during the reaction. Additionally, Co₂Cu₁ LDH presented an excellent stability and worked over a wide pH range. The hydroxide states of Co(III), Co(II), Cu(I) and Cu(II) were all able to activate PMS, indicating that there were many active sites on the surface of Co₂Cu₁ LDH. The involvement of radicals in this reaction system was determined via scavenger experiments and electron paramagnetic resonance (EPR). Meanwhile, it's worth noting that a mathematical model was developed to quantify the involvement of SO₄^- and OH. Subsequently, we determined PMS activation mechanism and LOM decomposition pathway for the PMS/Co₂Cu₁ LDH system.

Keywords: Advance oxidation; Degradation pathway; Layered double hydroxides; Lomefloxacin; Peroxymonosulfate; Reactive species inducing route.