MoS2@SiO2 enhanced persulfate oxidation for the degradation of triazine herbicides in fixed-bed reactor

A continuous flow mode fixed-bed reactor (FBR) was built for the efficient degradation of triazine herbicides (THs) in wastewater, in which MoS2@SiO2 composites were used as a co-catalyst for the Fe2+ activated persulfate (PS) oxidation. The degradation activity of this MoS2@SiO2/PS/Fe2+ FBR was evaluated by choosing atrazine (ATZ) as a model pollutant, and operation conditions were systematically optimized, including the amount of oxidant, Fe2+ concentration, initial pH, flow rate, and coexisting interferences. The degradation results showed that MoS2@SiO2 could greatly improve the degradation efficiency, and over 97.1 % of ATZ could be degraded under the optimized conditions (hydraulic residence time of 24 s). In this reaction system, sulfate radicals and hydroxyl radicals played the major roles (over 80 %) in the degradation process. Continuous treatment of 1400 mL wastewater could be achieved with 1.0 g MoS2@SiO2 composite with a degradation efficiency maintained above 80 %. Four tested THs of ATZ, simazine, ametryn and prometryn could be efficiently degraded. Furthermore, the removal rate of ATZ in pond water reached 77.6 % and the mineralization rate was about 51 %, indicating this MoS2@SiO2/PS/Fe2+ FBR was applicable in the treatment of real wastewater.

Automated summary

A continuous flow mode fixed-bed reactor was constructed for efficient degradation of triazine herbicides in wastewater, using MoS2@SiO2 composites as a co-catalyst for the Fe2+ activated persulfate (PS) oxidation. The results showed that MoS2@SiO2 significantly improved the degradation efficiency, with over 97.1% atrazine being degraded under optimized conditions. Sulfate radicals and hydroxyl radicals played a major role in the degradation process.