Experimental Study On The Effects Of SO₄^2-and Cl^- On The Electrocatalytic Oxidation Of Organic Pollutants

Electrocatalytic oxidation technology is widely used in the treatment of high salt organic wastewater due to its advantages of easy control,environmental compatibility,and stable oxidation performance.However,actual wastewater typically contains a large amount of SO₄^2-and Cl^-,and the presence of these anions has a significant impact on the process of electrocatalytic oxidation of organic pollutants.Based on this,this study used phenol as a model organic compound and conducted electrochemical testing and water treatment experiments on simulated wastewater in the presence of SO₄^2-and Cl^-anions.Combined with stage reaction kinetics models and mass transfer coefficients,the degradation mechanism of phenol under different anionic species was analyzed.The main conclusions are as follows:（1）The electrochemical test results show that the electrocatalytic activity of Pb O₂/Ti and Ir O₂-Ta₂O₅/Ti electrodes in the system containing Cl^-phenol is higher than that in the system containing SO₄^2-phenol,which is reflected in higher external active voltammetric charge,Exchange current density and lower Tafel slope;Simultaneously,by introducing the anodic oxidation coefficient（γ）quantitatively describing the oxidation ability of organic matter in electrodes,it was found that in two anionic systems,Pb O₂/Ti and Ir O₂-Ta₂O₅/Ti electrodesγthe values are both 0.98and 0.21,indicating that the oxidation ability of the electrode to organic matter will not change due to the different types of anions in both systems.（2）Experiments were conducted on the electrocatalytic oxidation of phenol in systems containing Cl^-phenol and SO₄^2-phenol,exploring the effects of current density and electrolyte concentration on the degradation efficiency of phenol under different anion types.The results showed that current density can affect the removal efficiency of phenol by controlling the amount of active substances produced and the mass transfer process,while the effect of electrolyte concentration is not significant,and under the same experimental conditions,The COD removal rate,average current efficiency,and system energy consumption of the two electrodes in the system containing Cl^-phenol are better than those in the system containing SO₄^2-phenol.（3）The intermediate products of phenol degradation were analyzed by UV spectrum scanning.In the system containing SO₄^2-phenol,phenol was oxidized by the hydroxyl radical generated on the electrode surface to benzoquinone and other intermediate products,and finally to CO₂ and H₂O.The oxidation efficiency of phenol in this system depends on the ability of the electrode material to produce hydroxyl radical,that is,theγValue;In the system containing Cl^-phenol,the electrically active ion Cl^-in the system generates active chlorine under the action of the electrode,which rapidly reacts with organic matter to generate intermediate products such as hydroquinone and chlorinated organic matter,and exhibits a faster removal rate of organic matter.（4）By fitting the water treatment results with the established stage reaction kinetics model,the mass transfer coefficient（k_m）of the reaction system was obtained,and further analysis was conducted on the mass transfer coefficient.It was found that the influence of anion species on electrocatalytic oxidation was mainly reflected through the side wall effect.The weaker the side wall effect,the faster the mass transfer process in the system,while the side wall effect of the system containing Cl^-phenol was weaker than that of the system containing SO₄^2-phenol,Therefore,the former has a larger mass transfer coefficient and better treatment effect;Finally,based on the results of UV spectral scanning and electrochemical testing,it is speculated that the types of anions mainly affect the sidewall effect of the system through the process of oxygen or chlorine evolution on the electrode surface and the type of intermediate products of organic matter oxidation,thereby affecting the water treatment efficiency.The thesis consists of 17 figures,6 tables,and 106 references.