Comparison Of Several Advanced Oxidation Low Concentration Dimethylformamide Wastewater Treatment

With the continuous development of my country’s industrialization process,dimethylformamide has become an increasingly prominent necessity in various production industries such as chemical industry,tanning,pesticides,and medicine.Dimethylformamide has gradually emerged while advancing the development of industrialization.The problem of environmental pollution caused when dimethylformamide is used in large quantities.However,due to the useful and very strong dissolving power of dimethylformamide,in addition to saturated hydrocarbons such as gasoline,hexane and cyclohexane,it can be mixed with water,ethers,alcohols,esters,ketones,unsaturated hydrocarbons and aromatic hydrocarbons in any ratio.Other organic solvents are mutually soluble,have stable chemical properties,are difficult to degrade,are harmful to the environment,are toxic,and are harmful to the human body.Therefore,the harmless treatment of dimethylformamide has become a popular research direction.There are different treatment methods for wastewater with different concentrations of dimethylformamide.For wastewater with higher DMF concentration（>1.0%）,recycling technology is generally used for treatment,specifically distillation and rectification,extraction and adsorption-extraction Law and so on.For wastewater containing low concentration of DMF（<0.5%）,the above recovery technology is used to treat the DMF recovery cost is high,and it is not economically feasible.Long-term research has been carried out on the treatment of this type of low concentration DMF wastewater.At present,the main biochemical method is And advanced oxidation method,etc.Due to the stable chemical properties of dimethylformamide,its biochemical oxygen demand（BOD）to chemical oxygen demand（COD）ratio is 0.065,which does not reach the biochemical conditions,is difficult to be biodegraded,and will inhibit the process of biochemical treatment of wastewater It affects the treatment effect,so the advanced oxidation method is used to treat the low concentration of dimethylformamide.This subject uses photocatalysis,Fenton oxidation,ozone and hydrogen peroxide oxidation,and combined technologies to conduct in-depth experimental research on the degradation and mineralization of dimethylformamide.The main research contents are as follows:（1）Photocatalytic oxidation degradation of dimethylformamide was carried out in single-factor experimental study,and the operating conditions of the reaction were determined.On this basis,through the response surface test design,the three main factors of photocatalytic oxidation treatment of dimethylformamide were determined.Factors-p H,circulating flow and air aeration are optimized.The best operating conditions are 90L/min for circulating flow,10L/min for air aeration,and p H 10 for the solution,corresponding to the dimethylformamide The degradation rate is 13%.（2）Fenton’s oxidative degradation of dimethylformamide was carried out by a single-factor experimental study,and the operating conditions of the reaction were determined.On this basis,through the response surface test design,the three main factors of Fenton’s oxidation treatment of dimethylformamide were determined.——PH,hydrogen peroxide dosage and n（H₂O₂）:n(Fe²⁺)ratio are optimized.The best operating conditions are 27.5%hydrogen peroxide dosage 1.06ml/L,n（H₂O₂）:n(Fe²⁺)=1.42,Solution p H=3.12,and the corresponding degradation rate of dimethylformamide reaches 100%.（3）Ozone oxidation degradation of dimethylformamide was carried out in a single factor test study,and the optimal ozone dosage was determined to be 0.6g/L,and the corresponding degradation rate of dimethylformamide reached 72.69%.H₂O₂degradation of dimethylformamide was carried out in a single factor experiment.When the dosage of H₂O₂reached 1.0ml/L,the degradation rate of DMF reached15.73%.（4）Among the single Fenton oxidation technology,ozone oxidation technology,H2O2 oxidation and photocatalytic oxidation degradation of DMF,Fenton oxidation has the best effect,and the others decrease in order.（5）Experimental study on the combined degradation and mineralization of dimethylformamide using two oxidation technologies.The combination of photocatalytic oxidation and Fenton oxidation did not improve the degradation effect of DMF,and Fenton oxidation was the main one;the combination of photocatalysis/O₃oxidation and photocatalysis/H₂O₂oxidation both improved the degradation and mineralization effects of DMF,and there were photocatalysis and O₃oxidation.There is a coupling effect;the UV/O₃oxidation combination also improves the degradation and mineralization effects of DMF.The presence of 254nm UV has a synergistic effect on O₃oxidation,and 185nm VUV has an antagonistic effect on O₃oxidation.The photocatalysis/O₃oxidation combination is the best among the two oxidation technology combinations.（6）Experimental study on the combined degradation and mineralization of dimethylformamide with three oxidation technologies.UV/H₂O₂/O₃and photocatalysis/H₂O₂/O₃combined treatment of DMF have a greater effect.Under185nm VUV,the combined oxidative degradation reaction rate of UV/H₂O₂/O₃is12.40,2.67,2.72 and 3.34 times of H₂O₂oxidation,O₃oxidation,UV/H₂O₂and UV/O₃respectively;photocatalysis/H₂O₂/O₃combined oxidative degradation reaction rate They are 12.20,3.70,3.99 and 1.33 times of H₂O₂oxidation,O₃oxidation,photocatalysis/H₂O₂and photocatalysis/O₃,respectively,indicating that UV/O₃/H₂O₂and photocatalysis/O₃/H₂O₂combined technologies have synergistic and coupling effects,among which photocatalysis/The combination of H₂O₂/O₃degrades and mineralizes dimethylformamide has the best effect.（7）In addition to Fenton oxidation,the combination of ozone oxidation technology,H₂O₂oxidation and photocatalytic oxidation degrades and mineralizes dimethylformamide.The combination of photocatalysis/O₃/H₂O₂and photocatalysis/O₃oxidation is more effective,considering that the process is simple and feasible.In terms of operating costs,the photocatalysis/O₃oxidation combination is more suitable than the UV/O₃/H₂O₂oxidation combination technology.