Persulfate coupled with Cu2+/LDH-MoS4: A novel process for the efficient atrazine abatement, mechanism and degradation pathway

The Cu-based catalytic activation of persulfate is considered very attractive to deal with the growing concern of water pollution. However, the difficulty in regenerating Cu+ from Cu2+ restricts it from widespread field applications. This work described the regeneration of Cu+ with the help of layered double hydroxide (LDH-MoS4), being used as a co-catalyst in the Cu2+/persulfate process. The results revealed that the Cu2+/LDH-MoS4/per-sulfate (PS) system offered better efficiency (30 times) than the normal Cu2+/PS process. Also, the Cu2+/LDH-MoS4/PS system demonstrated faster removal of atrazine (10-20 times) than the recently reported Cu2+/WS2/ PS, Cu2+/MoS2/PS or Cu2+/Mo/PS co-catalytic systems or other tested systems, i.e., Cu2+/LDH-BH4/PS, Cu2+/ LDH-EDTA/PS etc. This excellent performance of the Cu2+/LDH-MoS4/PS system was related to the constant regeneration of Cu+ from the reduction of Cu2+ ions, which minimizes the effect of the rate-limiting step during reactions. Furthermore, the Cu2+/LDH-MoS4/PS system exhibited good efficiency over a wide pH range (3.0-9.0), high oxidant utilization efficiency, excellent activities during recycling, less susceptibility in the presence of certain electrolytes or organic matters. This study provides the co-catalysts intrinsic role in reducing the Cu2+ ions by continuously feeding electrons from the unsaturated S2-and Mo4+ of LDH-MoS4.