Preparation Of Fe-doped MoS₂ Catalysts And Its Degradation Performance Of Rhodamine B

The environmental pollution caused by the discharge of dye wastewater has attracted worldwide attention,and realizing the efficient degradation of dye wastewater will be a major test on the road of human sustainable development.The traditional Fenton method utilizes the hydroxyl radicals（·OH）generated by hydrogen peroxide（H₂O₂）under the catalysis of Fe²⁺to degrade organic pollutants.However,the traditional Fenton method has problems such as a narrow pH range（around pH=3）and the inability to recover the catalyst.Based on this,this thesis firstly takes molybdenum disulfide（MoS₂）solid catalyst with wide pH applicability as the research subject,and iron element with H₂O₂ activation effect is selected to modify MoS₂,so as to construct Fenton-like system of Fe-MoS₂ catalyst to improve the activity of the catalyst in a wide pH range.On this basis,according to the material characteristics of Fe-MoS₂ and considering the promoting effect of photo-generated electrons on the reduction of high valence metal ions,visible light is introduced into the Fenton-like system of Fe-MoS₂ in this paper,so as to construct the photo-Fenton-like system of Fe-MoS₂ to further degrade organic pollutants.The main research work is as follows:（1）MoS₂ and a series of Fe-doped MoS₂ catalysts（x%Fe-MoS₂）were prepared by hydrothermal method,and the performance of the catalyst was evaluated by Fenton-like reaction to degrade Rhodamine B.The results showed that the degradation activity of Fe-MoS₂catalyst after 30 min was better than that of MoS₂（54.77%）,and 5%Fe-MoS₂ showed the best degradation activity（99%）,which was 1.81 times of that of MoS₂,and the activity did not obviously decrease after four cycles.In addition,the effects of H₂O₂（3 M）dosage and different inorganic ions on the degradation of RhB in 5%Fe-MoS₂ catalyst Fenton-like system were investigated.Moreover,the experimental study found that the Fenton-like degrading performance of Fe-MoS₂ for RhB maintained high activity in the pH range of 3-11.Combined with BET,XPS and trapping agent experiments,this paper points out that the reason for the better Fenton-like activity of Fe-MoS₂ catalyst is that besides the Fenton-like activity of MoS₂and iron ion itself,the increase of specific surface area and the redox between Fe³⁺/Fe²⁺and Mo⁴⁺/Mo⁶⁺also play a crucial role in enhancing the Fenton-like activity of Fe-MoS₂ catalyst.（2）The photo-Fenton-like system was constructed to evaluate the performance of Fe-MoS₂catalyst for degrading RhB.The experimental results confirmed that the Fenton-like system and the photocatalytic system of Fe-MoS₂ catalyst can produce a synergistic effect in degrading organic pollutants,and when the dosage of H₂O₂ in photo-Fenton-like system（40μL）is 13.33%of that of Fenton-like system,the introduction of visible light can make the two systems achieve similar degradation performance within 30 min.In addition,the effects of inorganic ions and the initial pH of RhB solution on the photo-Fenton-like degradation performance of Fe-MoS₂were investigated.Combined with XPS,DRS,PC and other characterizations and capture agent experiments,the degradation mechanism was analyzed,and its activity can be attributed to:1)The Fenton-like effect of Fe-MoS₂ catalyst;2)Fe-MoS₂ catalyst improves the photocatalytic oxidation of RhB by MoS₂ itself;3)Photogenerated electrons can promote the conversion of high valence metal ions to low valence metal ions and can also react with H₂O₂ to generate more active free radicals.This process is not only conducive to the reduction of high valence metal ions in the Fenton-like system,but also conducive to the separation of photo-generated electrons and holes in the photocatalytic system.Ultimately,these factors work together to enhance the degradation activity of Fe-MoS₂ in the photo-Fenton-like system.