Electrochemical Mechanism Of Micro-electrolysis On Treatment Of Wastewater Containing Organic Reagents From Mineral Processing And Its Degradation System

The treatment of industrial wastewater containing organic pollutants is a major issue faced by the current economic and social development.Non-ferrous metal mineral processing wastewater generally contains residual organic agents,which cannot be directly discharged and needs deep treatment.It is of great significance to develop the degradation and recycling purification technology of organic pollutants in mineral processing wastewater.Microelectrolysis has been widely used in the field of chemical and pharmaceutical organic wastewater treatment,but there are still some problems in the treatment of mineral processing wastewater by microelectrolysis,such as imperfect electrochemical mechanisms and difficult degradation materials and processes to meet the existing wastewater treatment requirements.The elementary reaction of microelectrolysis was studied from three aspects:anodic reaction,electron transfer between anode and cathode and cathodic reaction.The interaction between the cathode material and organic matter and the effect of basic electronic steps on the surface of the cathode material on the micro reaction were explained respectively by molecular dynamics and quantum chemical calculations.Based on the excellent properties of carbon and copper cathode materials,the Fe-C、Fe-Cu and Fe-C-Cu microelectrolysis systems were designed and investigated.The degradation performances for organic pollutants by microelectrolysis mateirals were evaluated.Copper slag was used to synthesize the filler,which was with higher performance and lower cost,by using the high-temperature reaction characteristics of different components.The treatment effect of actual wastewater was investigated.The specific research contents are as follows:（1）The unit process and mechanism of micro electrolysis were studied in detail.The charge transfer between anode and cathode electrodes and the mechanism of the reaction of cathode elements were mainly studied by chronoamperometry methods through a galvanic two-electrode system.The charge transfer between anode and cathode is respectively driven by O₂ and H⁺around the cathode for oxidizing atmosphere and non-oxidizing atmosphere.The electron transfer rate is influenced by the electron transfer step that has a（35）G_max in oxygen reduction reaction（ORR）and hydrogen generation reaction（HER）,and restricted by the amount active sites on the cathode surface.The O₂ diffusion can improve the electron transfer rate greatly.For different cathode materials,p H value has different effects on charge transfer of anode and cathode.Metal cathode systems can be greatly affected by the p H value,which is mainly related to basic electronic steps on the cathode surface.The adsorption between organic matter and the cathode will reduce the self-discharge current between the two poles.When the p H value was near 3,the signals of hydroxyl radicals and hydrogen radicals in the solution were strongest,and the current efficiency of organic degradation was the highest.The two-electron step of cathodic oxygen reduction was the precondition for·OH generation.Organic agents can be directly oxidized under the catalysis of specific cathode materials.The foamed cobalt electrode has good electrocatalytic degradation ability to isobutyl xanthate（IBX）and ethyl disulfide（DDTC）.The active objects degrading IBX and DDTC in microelectrolysis include·OH,·OOH,H₂O₂,etc.（2）The Fe-C microelectrolysis system for pollutants degradation was studied through the Fe-C filler.From the view of the phase transformation of filler ingredients at high temperature,the filler preparation process was optimized.The generation of Fe₂Si O₄ in filler structure facilitated the formation of the integrated structure,which enhances the mineralization capacity and extends the service life of the filler.The optimized filler was with abundant pore structure,good physical properties and excellent degradation performance.At p H 7,first order kinetic rate constant k for IBX degradation was 0.0288 min^-1.When the reaction time was 90 min,the removal rate of IBX reached 93.26%,and the COD removal rate of wastewater was close to 80%.The fayalite-phase Fe-C filler system has stable degradation performance of IBX and good prospect for long-term running.（3）The strengthening mechanism and effect of copper on Fe/Fe-C micro-electrolysis system were studied.An Fe@Cu microelectrolysis material with high catalytic activity was prepared by a simple substitution reaction,and its degradation of2,4-DCP,IBX and DDTC was investigated.The prepared Fe@Cu microelectrolysis material possesses a large specific surface area,a small particle diameter,and a loose accumulation,which not only provides a large specific surface area for the cathode reaction but also provides a channel for the anodic iron to release ions.2,4-DCP can be completely degraded within 30 min by Fe@Cu,maintaining high degradation activity for 2,4-DCP during five cycle experiments.The Fe@Cu exhibited high degradation activity to DDTC and can maintain high activity for repeating utilization.The Fe@Cu can also degrade IBX,but the reutilization of Fe@Cu was difficult due to the strong collecting function of IBX.The effect of metal addition was investigated in combination with the cathodic catalytic results of microelectrolysis.The k of the degradation for IBX with Fe-C-Cu filler was as high as 0.0484 min^-1.The degradation rate of IBX increased from 93%to 98.97%,and the removal rate of COD increased from 77.53%to 87.48%.（4）Traditional smelting solid waste copper slag was used to prepare filler,improving performance of the filler as well as realizing one-step resource utilization of copper slag.The Fe₂Si O₄ in copper slag was reduced to Fe by the C and Na₂CO₃ during filler roasting,which increased the content of active substances of the filler and was conducive to the formation of the integrated structure of the filler.When the content of copper slag in the raw material was 15 wt.%and Na₂CO₃ was 4.5 wt.%,the k of IBX degradation could reach 0.0548 min^-1.The filler has a good treatment effect on the actual wastewater of high-sulfur bauxite and molybdenum ore dressing.When filler was used to treat high-sulfur bauxite mineral processing wastewater,the mineralization efficiency of organic pollutants was 41.63%,and the COD concentration of the treated wastewater was 27.09 mg/L.When filler was used for the treatment of molybdenum ore processing wastewater,the mineralization efficiency of organic pollutants in the wastewater was 51.90%,and the indicators such as total phosphorus,ammonia nitrogen,chroma were greatly changed.The water quality parameters were greatly improved,laying a good foundation for the subsequent in-depth treatment of wastewater.