Study On Mechanism Of Electrolytic Desalination Of High Salt Organic Wastewater By Ion Exchange Membrane

High salt organic wastewater is the product of modern industrialization,which has a large amount of yield and complex ingredients.If it cannot be successfully recycled,lots of water resources would be wasted,which could also cause great harm to the environment.In the high salinity environment,the growth of microorganism is inhibited and the biological activity is reduced.In addition,some traditional physical and chemical methods have a high processing cost,and need to add additional chemicals,which is likely to cause secondary pollution.These shortcomings make it difficult to deal with high salt organic wastewater efficiently and efficiently.High salt organic wastewater has a high conductivity,which improve a good development space for the electrochemical application in the wastewater treatment.Membrane electrolysis technology as an important part of the electrochemical process combines the characteristics of electrodialysis and electrolysis.The technology can not only desalinate but also can degrade organic matters.There is no doubt that it has a great application potential and research value for the high salt organic wastewater treatment.In this paper,ion-exchange membrane electrolysis technology was used to study the desalination mechanism and the degradation of organic matters from high salt organic wastewater.The self-made removable multi-stage membrane electrolyzer unit was used for membrane electrolysis experiments.The material of Ti/RO2-Ir O2-Sn O2 was used as plate material.Na~+ and Cl-are the target remove ions.The organic compounds in the simulated wastewater mainly contain methyl orange,acid red 3R,direct dark brown and reactive brilliant blue X-BR.The experiment was carried out under the action of a DC electric field.The effects of the control conditions such as current density,plate spacing,electrolyte concentration and injection flow rate on the desalting effect were discussed under the condition of single membrane electrolysis.In the process of double membrane electrolysis,the desalting effect and degradation of organic matter were studied.And there were also some works to analyze the problem of contamination cleaning of homogeneous anion and cation exchange membranes used in the experiments.Through the quantitative analysis of the p H,conductivity,salt concentration,TOC concentration and chroma of water samples,and the qualitative analysis of the surface morphology of ion membranes and the electrolyte of organic compounds using environmental scanning electron microscopy(SEM)and fourier transform infrared spectroscopy(FTIR),respectively,some conclusions were summarized,as follows:The effect of current density on the desalting effect was the most significant in the membrane electrolysis desalting process.The optimum operating conditions are as follows: the current density is55.6m A/cm2,the plate spacing is 2cm,the electrolyte concentration is2g/L,the injection flow rate is 50 m L/min.Under these conditions,the Cl-and Na~+ removal rate could reach about 70% and 90%,respectively,in the process of the single membrane electrolysis.And the removal rate of the two kinds of salt ions all could reach about 90% in the process of double membrane electrolytic treatment from the simulated dye wastewater.At the same time,the dye organic matters could also be degraded to a certain extent.The TOC removal rate of methyl orange could reach about 75%,which was the best treatment effect in the several substances.It is worth noting that the ion-exchange membrane can also effectively block the migration of organic matter.In the process of membrane electrolysis,the salt ions can bedirectional migration under the action of the DC electric field,and they adsorb on the surface of the ion exchange membrane by electrostatic interaction,then migrating.The experimental results showed that the p H of the solution in the anodic liquid was maintained at 2-3 through chlorine evolution reaction and oxygen evolution reaction,and the p H of the cathodic liquid was maintained at around 13 through hydrogen evolution reaction.When organic matters were present in the salt solution,they would be oxidatived degradation by the active chlorine substances(Cl2,HCl O,Cl-)and hydroxyl radicals(?OH)generated from the electrochemical reactions.What's more,the electrochemical oxidation process can effectively remove the chroma of the dye materials.And the infrared spectra showed that the molecular structure of the dye is destroyed,especially the functional groups of-N=N-,=C=C=,=C=O.And the simpler the molecular structures are,the better electrolysis effect will be,the higher the chroma removal rate will be.Finally,the results of the scanning electron microscopy of ion exchange membranes showed that a large amount of material were adsorbed on the surface of the used homogeneous cation exchange membrane,and there were many cracks in the surface of the used homogeneous anion exchange membrane.After acid-base cleaning and ultrasonic cleaning,the surface of the cation exchange membrane became smooth,and the cracks on the surface of the anion exchange membrane did not changed too much.Comparison of the desalination effect of the membranes before and after cleaning,the result showed that the combined membrane cleaning method used in the experiment can effectively remove the pollution caused by the organic matter and inorganic salt precipitation on the membrane surface,and then restore the desalination performance of the ion exchange membranes.