Preparation And Catalytic Properties Of Molybdenum Disulfide Based Nanocomposites

Antibiotics were widely used to treat bacterial diseases and enter the aquatic environment through urine and excreta,posing a threat to human health and the ecological environment.The fenton-like reaction based on sulfate radical(SO₄^·-)had the advantages of efficiency,speed,and thorough oxidation,and was widely used for the removal of organic pollutants in water.Peroxomonosulfate（PMS）with asymmetric structure had high solubility and low activation energy required.Its oxidation capacity was enhanced mainly by adding heterogeneous catalysts.Molybdenum disulfide（MoS₂）was a typical two-dimensional semiconductor material in transition metal chalcogenides and had become a new heterogeneous catalyst with high attention in recent years.It had suitable band gap and stable chemical properties,and had been widely studied in catalytic degradation of organic pollution.In fact,commercial bulk Mo S₂had reduced its specific surface area and electron transfer efficiency due to stacking,which limited its catalytic activity.Considering the advantages of Mo S₂in catalysis,this article used hydrothermal synthesis to prepare Mo S₂nanomaterials and Co Fe₂O₄/Mo S₂composite materials by coupling and loading modification methods,improved catalytic activity and used them as activators for PMS.By using tetracycline（TC）and norfloxacin（NOR）as target pollutants,the degradation efficiency and mechanism of the reaction system were explored,the stability of the catalyst was investigated.The main content and results were as follows:Using sodium molybdate and cysteine as raw materials,flower-like Mo S₂nanomaterials were prepared by hydrothermal synthesis.Compared with bulk Mo S₂,flower-like Mo S₂consists of nanosheets structure,had a large specific surface area and rich active site,which helped to enhance the adsorption effect of pollutants and the activation efficiency of system.The presence of Mo S₂could stabilize the reduction of Fe³⁺to Fe²⁺.After Mo S₂reached adsorption equilibrium for tetracycline,PMS was added to the system to further degrade TC.Under the redox cycling of Mo and Fe ions with different valence states,PMS was continuously activated to degrade TC through radical processes(·OH,SO₄^·-and O₂^·-)and non-radical processes（Fe^Ⅳ=O and ¹O₂）.The experimental results showed that the Mo S₂/Fe³⁺/PMS system had strong adaptability over a wide p H range（3-9）,and even at p H=11,the system could achieve a removal rate of over 80%for TC.The intermediates generated during the degradation process were detected using LC-MS,and two possible pathways of TC degradation were speculated.The toxicity of the intermediates was evaluated by T.E.S.T.Combined with inorganic anion experiments and recycling experiments,the stability and recycling economy of Mo S₂material were demonstrated.To further improve the catalytic activity of the catalyst,Co Fe₂O₄microspheres were uniformly loaded on the surface of Mo S₂by hydrothermal method to prepare Co Fe₂O₄/Mo S₂composite materials.The synergistic effect between multiple metals significantly promoted the activation effect of PMS.A series of composite materials were prepared by controlling Co/Mo ratio.The experiment showed that under neutral conditions with Co/Mo ratio of 5,catalyst dosage of 0.1 g/L,and PMS concentration of 0.2 m M,the removal rate of NOR reached 87.2%after 30 minutes of reaction.¹O₂was the main active species in the reaction,with a contribution rate of 87.1%.Expounded the mechanism of degradation reaction,inferred three possible pathways for NOR degradation,and predicted multiple toxicity data of the product.The H₂PO₄^-in the solution had the strongest inhibitory effect,and Co Fe₂O₄/Mo S₂composite material could adapt to the influence of various inorganic anions and humic acids,and had good removal effects on various pollutants.