Preparation Of MoS₂/g-C₃N₄ Catalyst And Its Application In The Degradation Of Malachite Green And DMSO

Malachite green and dimethyl sulfoxide（DMSO）are widely used in medicine,chemical industry and other various fields,but they not only have high residues in natural water,but also produce toxic and harmful substances,which will bring serious impact on the natural environment and human health.In actual projects,it is difficult to use biological method or traditional physical and chemical method to treat them.Therefore,it has become an urgent problem to choose a suitable method to treat such wastewater.Based on the above problems,MoS₂/g-C₃N₄ composite catalyst was prepared in this study.In order to prepare a highly efficient MoS₂/g-C₃N₄ catalyst which could improve the degradation rate of malachite green in the system,the factors affecting the catalytic efficiency of the catalyst was studied in the persulfate oxidation system.Apart from this,ultrasonic technology was applied to the system to degrade DMSO,which provided an experimental basis for the treatment of DMSO by ultrasonic combined with persulfate oxidation technology.The main research contents and results are as follows:（1）MoS₂/g-C₃N₄ catalyst was prepared by hydrothermal method and used in the advanced oxidation of persulfate system.When the hydrothermal reaction time was 15h and the dosage of Na₂Mo O₄·2H₂O was 1.5mmol（marked as 1.5-MoS₂/g-C₃N₄）,the1.5-MoS₂/g-C₃N₄ catalyst had the best degradation effect on malachite green.The results of XRD,XPS and SEM showed that the morphology of the 1.5-MoS₂/g-C₃N₄catalyst was a flower-like spherical sphere.In the catalyst,MoS₂ was well combined with g-C₃N₄,which made the active point of the catalyst increase and the activation rate of persulfate significantly increase.Malachite green was removed by advanced oxidation of persulfate method.The experiment was carried out under the following conditions:p H=4.67,the concentration of the solution of malachite green was 20mg/L,the concentration of the catalyst was 1.0g/L,the concentration of sodium persulfate was2mmol/L.After 30min of reaction,the removal rate of malachite green reached 99.89%.In the reaction system,SO₄^-·and HO·played a major role in the degradation process,while a small amount of O₂^-·and HO₂·also participated in the degradation of malachite green.The catalyst had good reusable properties.（2）The persulfate was activated by MoS₂/g-C₃N₄ catalyst,and the DMSO was degraded with the assistance of ultrasonic technology.Under the conditions of p H=3.13,the concentration of the solution of DMSO 20mg/L,the concentration of the catalyst0.5g/L,the concentration of sodium persulfate 6mmol/L,ultrasonic power 200W,the removal rate of DMSO could reach 100%within 60min.In this reaction system,SO₄^-·and HO·played a major role in the degradation process.The 1.5-MoS₂/g-C₃N₄catalyst was characterized by SEM,XRD and FTIR.The results showed that the morphology,crystal structure and chemical bond of the catalysts were basically unchanged,which further indicated that the catalyst had good reusable properties.（3）The 1.5-MoS₂/g-C₃N₄/Fe₃O₄ catalyst with magnetic properties was successfully prepared by ultrasonic impregnation method.In order to explore the catalytic performance of 1.5-MoS₂/g-C₃N₄ catalyst after magnetic support,it was used as catalysts in the reaction systems of（1）and（2）:the degradation rate of malachite green is 98.46%in 30min,and the degradation rate of DMSO is 100%in 8min.It might be due to the synergistic catalysis of Fe₃O₄ that the removal rate of DMSO is significantly improved The ESR test showed that HO·was produced in the reaction system and involved in the degradation of DMSO.According to the SEM and XRD characterization,the flower-shaped 1.5-MoS₂/g-C₃N₄ catalyst were successfully supported on the surface of Fe₃O₄ nanoparticles,besides the catalyst was stable in the reaction process.