Preparation Of MgO-based Activator And Study On Activating PMS To Degrade Rhodamine B

As a common dye,Rhodamine B will destroy the self-purification ability of the water body after entering the water body,resulting in an imbalance of the water environment.Therefore,it is necessary to treat and discharge Rhodamine B wastewater.However,due to the complexity and stubbornness of the dye,the traditional treatment method is not suitable for It is difficult to remove,so it is extremely important to seek a simple and efficient treatment method.Among the new treatment technologies,advanced persulfate oxidation technology can efficiently treat refractory wastewater,but persulfate needs to be activated to effectively degrade organic pollutants.In view of this,three kinds of Mg O-based bimetallic oxides were prepared by precipitation method:magnesium oxide/copper oxide（Mg O/Cu O）,magnesium oxide/iron oxide（Mg O/Fe₂O₃）,magnesium oxide/alumina（Mg O/Alumina）Al₂O₃),in which the preparation and addition ratio of the bimetallic oxide precursor is（1:0.5,1:1,1:1.5）,and the prepared activator was subjected to the activation of potassium hydrogen persulfate（PMS）to degrade rhodamine B test,and carried out Research on influencing factors and mechanism exploration.The main findings are as follows:（1）The performance comparison of activator-activated PMS to degrade Rhodamine B was carried out.Among the prepared three bimetallic catalysts（Mg O/Cu O,Mg O/Fe₂O₃,Mg O/Al₂O₃）,the most ideal activator for activating PMS to degrade Rhodamine B is Mg O/Cu O,and Mg O/Cu O degrades Rhodamine B The ratio of Mg O/Cu O is more than 40%higher than that of the other two catalysts,and the degradation of Rhodamine B is more than 95%after 5minutes of reaction.When the preparation conditions of Mg O/Cu O are the addition ratio of 1:1and the calcination temperature of 500°C,the The activation performance of PMS is ideal.（2）The activation effect of the PMS&Mg O/Cu O system was optimized,and the effects of different contents of Rhodamine B,PMS and Mg O/Cu O on the system were studied.In the single factor experiment,when the concentration of Rhodamine B,the dosage of Mg O/Cu O and the dosage of PMS were 10mg/L,0.3g/L and 0.5g/L,respectively,the system had the best degradation effect on Rhodamine B;The influence of the three on the degradation system was obtained from the cross-experiment:the concentration of Rhodamine B>the dosage of PMS>the dosage of catalyst,and the three had no significant effect on the removal of Rhodamine B;the repetition of Mg O/Cu O activator The utilization rate is good,and the final removal rate of Mg O/Cu O to Rhodamine B after three reactions is less than 5%;SEM and XPS characterization can show that the elemental composition of the Mg O/Cu O catalyst does not change before and after the reaction.（3）The effects of different water conditions on the PMS&Mg O/Cu O system were studied.Under the conditions of different water p H（3～9）,the effect of Mg O/Cu O activated PMS to degrade Rhodamine B reached more than 98%,showing strong applicability in a wide p H range;Under the condition of 200mg/L,the degradation effect of rhodamine B in the system was more than 98%,indicating that humic acid had little effect on the reaction system.The increase of the reaction system first inhibits and then promotes the reaction system.NO₃^-has little effect on the reaction system.HCO₃^-,SO₄^2-,PO₄^3-have inhibitory effects on the reaction system,and the higher the concentration,the stronger the inhibitory effect.Among them,PO₄^3-has the strongest inhibitory effect.（4）The degradation mechanism and process of the PMS&Mg O/Cu O reaction system were analyzed.The main active species in the PMS&Mg O/Cu O reaction system are singlet oxygen（¹O₂）,sulfate radical（SO₄^-·）,hydroxyl radical（·OH）and superoxide anion radical（O₂^-·）on PMS.Activation plays a secondary role;the singlet oxygen source（¹O₂）originates from the cleavage and disproportionation of the peroxy bond（O-O）of the PMS itself,sulfate radical（SO₄^-·）,hydroxyl radical（·OH）and superoxide anion free The generation of radicals（O₂^-·）is mainly related to the catalytic decomposition process of PMS.The hydroxyl groups in solution and the surface hydroxyl groups of Mg O/Cu O also have a small contribution to the activation of PMS;the oxygen vacancies on the surface of Mg O/Cu O are the active sites for activating PMS.It acts as an intermediate in the process of activating PMS and promotes the generation of singlet oxygen（¹O₂）in the reaction system.