Research On Treatment Of Reverse Osmosis Concentrates By Anode And Cathode Synergy In Electrochemical Oxidation

Reverse osmosis is a membrane separation technique that uses a pressure difference as the driving force by selecting the function of the permeation membrane.Rapid development in the past 20 years,due to the simple process of reverse osmosis,low energy consumption.It is now widely used in seawater desalination,brackish water desalination,and wastewater treatment in various industries.At the same time,it is combined with ion exchange to produce high-purity water.Its application range is continuously expanding,and it is of great significance for environmental protection and sustainable development,and has huge economic benefits for water-scarce areas.However,the reverse osmosis process usually produces about one-third of concentrated water,which has now become a major bottleneck and a problem for wastewater treatment.Due to the high concentration of dissolved organics,ammonia and other pollutants,high salt content,poor biodegradability,etc.In this experiment,based on the electrochemical oxidation,using Ti/RuO₂-IrO₂ as the anode,Fe-FeOx/carbon aerogel（FCA）as the cathode,and the proton exchange membrane as the separator,no external metal catalyst is required.The oxidation of the anode is fully combined with the oxidation of the cathodic reduction product,the cathode-anode synergy technology is applied and a new electrochemical system is used to effectively degrade pollutants in reverse osmosis concentrates.（1）The carbon aerogel electrode was synthesized by the sol-gel method,and the Fe-FeOx/carbon aerogel electrode was prepared by one-step synthesis method.Through physical and chemical tests and characterization,the results show that the carbon aerogel base material has a good conductivity of 26.67 S/cm,a lower density of 0.2965 g/cm³ and a relatively large specific surface area of 495.225 m²/g.The SEM spectrum shows that the prepared carbon aerogel material has good three-dimensional network structure and well-developed voids before and after high-temperature carbonization.After adding iron source,the conductivity,mechanical strength and electrochemical performance of FCA electrode have been enhanced.SEM,TEM and XRD spectra show that the FCA electrode also has a three-dimensional network structure,and the nano-iron particles are mainly in the form of iron and iron oxides.It is relatively uniformly loaded onto the carbon aerogel base material.Through electrochemical tests,the prepared electrodes have good oxygen reduction performance.（2）The production of H₂O₂ in CA electrode under different factors was also examined.Under the optimal conditions of current with 50 m A,aeration volume of 0.7 L/min and pH=7,the yield of H₂O₂ was 648.14 mg/L.What’s more,the direct and indirect methods proved that·OH is the main active free radical in the reaction system.In order to further verify the electrochemical oxidation performance of FCA electrode,the decolorization of methyl orange wastewater was also studied.Under optimal conditions,after 180 min,the decolorization rate of methyl orange was 100%.CA electrode and FCA electrode have good stability and service life.（3）The degradation of ammonia nitrogen and COD by different factors under sequential batch condition was performed with the anode and cathode separation and synergy function.The experimental results show that under the optimal conditions,the effect of ammonia and COD degradation through anode and anode synergy is better than the effect of cathode and anode alone.Anode and anode synergy,in the anode compartment,after 90 minutes,the concentration of ammonia nitrogen decreased from 50 mg/L to 0 mg/L,while COD decreased from 150 mg/L to 33.51 mg/L after 120 minutes.In the corresponding cathode chamber,the concentration of ammonia nitrogen was degraded from 50 mg/L to 210 mg/L after 210 min,and the COD was reduced from 150 mg/L to 42.11 mg/L after 240 min.（4）Based on the sequential batch experiments,a continuous experiment was established.Under the optimal conditions,the effects of simulated ammonia-nitrogen and COD degradation in reverse osmosis contaminates were examined through different influent modes.In the case where the anode and the cathode simultaneously feed water at the same time,ammonia nitrogen and COD have the best degradation effect.With ammonia decreased from50 mg/L to 6.22 mg/L after 8 h,and the corresponding COD decreased from 150 mg/L to39.51 mg/L after 8 h.