Degradation Characteristics Of 2-Chloro-4-Nitroaniline In UASB+A/O Electrochemical Coupling System

As the main intermediate product of the natural degradation of chloronitlosamide,2-chloro-4-nitroaniline has great toxicity to animals and plants,and is an organic compound difficult to biodegrade.It is of great significance to study the rapid and complete degradation of 2-chloro-4-nitroaniline.In this paper,the degradation characteristics of 2-chloro-4-nitroaniline aerobic（anaerobic）microbial electrochemical system were studied,and the influence of changing voltage exploration on two-compartment cathodic reduction and anodic oxidation,and the influence of changing voltage and concentration exploration on aerobic（anaerobic）deposition microbial electrochemical coupling system.To explore the influence of applied voltage,initial concentration of 2-chloro-4-nitroaniline and initial glucose dosage on the degradation of 2-chloro-4-nitroaniline by UASB+A/O electrochemical coupling system,and to explore the degradation path of 2-chloro-4-nitroaniline by HPLC and LC-MS-MS.Scanning electron microscope（SEM）was used to observe the changes of microbial number and community of sludge before and after degradation.The results are as follows:（1）The degradation effect of anodic oxidation（cathodic reduction）in the two-compartment microbial electrolysis cell is 10%higher than that of aerobic（anaerobic）microorganism alone or aerobic（anaerobic）electrolysis,indicating that the electroactive microorganism formed has a good degradation effect.In two-compartment cathodic reduction and anodic oxidation systems:When anodic oxidation was at 0.6-1.4V,with the increase of voltage,the stimulation of electroactive microorganisms was enhanced,and the degradation effect was also enhanced.The optimal voltage of cathodic reduction was at 1V,not 1.4V,indicating that the properties of aerobic and anaerobic electroactive microorganisms were different,and degradation was inhibited at 1.8V,which was related to water electrolysis.When the concentration of aerobic（anaerobic）deposition type microbial electrochemical coupling system is changed,the inhibition effect on electroactive microorganisms is greater with the increase of concentration,and the degradation effect is worse.The electrochemical coupling system of aerobic（anaerobic）deposition was better than that of aerobic（anaerobic）microorganism alone,aerobic（anaerobic）microorganism alone and two-compartment anodic oxidation（cathodic reduction）.The variation of the voltage of the aerobic（anaerobic）deposition microbial electrochemical coupling system at 0.6-1.8V was consistent with that of the two-compartment microbial electrolytic cell.（2）In the electrochemical coupling system of UASB+A/O process,the best condition is the applied voltage:1.4V;Initial concentration of 2-chloro-4-nitroaniline:10 mg·L^-1;Glucose dosage:1000 m L,the degradation rate of 2-chloro-4-nitroaniline was 8%at 20 h,compared with the degradation time of single aerobic and anaerobic microbial telep Hone coupling system,and improved the efficiency.（3）Through HPLC and LC-MS-MS detection,the possible degradation pathway of 2-chloro-4-nitroaniline was speculated as follows:2-chloro-4-nitroaniline degradation process can be generated under the effect of biological cathode dechlorination and reduction of nitro aniline and 2-chloro-4-amine aniline,on chlorine-4-nitroaniline and 2-amino aniline and dechlorination and reducing generation of p Henylene diamine,para-p Henylene diamine in the anodic oxidation is broken key ring opening,generation of p Henol open ring into 1-carboxyl-hydroxyl2-4 carbonyl butadiene,It then forms valerate,formic and acetic acid,and finally mineralizes into CO₂and H₂O.（4）through scanning electron microscopy（SEM）analysis of microorganisms found that aerobic microorganisms,anaerobic microorganisms in the electrochemical coupling system and UASB in before and after degradation,most microorganisms is given priority to with bacillus,a small amount of bacteria and filamentous bacteria,after reaction,the number and variety of microorganism to reduce to a certain extent,shows that 2-chloro-4-nitroaniline has certain toxic for microorganisms.