Study On The Parameters Of Hydrogen Peroxide Production And Power Generation Of Aluminum Air Cell And The Performance Of Tetracycline Degradation

Recently,the pollution caused by abuse of the antibiotics has become increasingly serious.Tetracycline（TC）,as one of the most commonly used antibiotics,is often detected in the water,which is a research hotspot.Fenton process is one of the effective methods to degrade tetracycline.However,the traditional Fenton method consumes a large amount of H₂O₂.In this paper,al-air fuel cell and Fenton oxidation were combined to generate H₂O₂in situ on the air cathode of al-air cell by two electron reduction of O₂.Then·OH was generated by Fenton reaction to degrade tetracycline.In the experiment,carbon material was used as the catalyst to prepare the air cathode.And the electrical performance and H₂O₂production capacity of aluminum air cell were investigated to detetermine the cathode catalyst with the best H₂O₂ production effect.The optimum parameters for H₂O₂ production and tetracycline degradation were obtained through comparative study.The main contents and conclusions of this paper are as follows:（1）Three kinds carbon materials of active carbon,carbon black,graphite were used as catalysts to prepare air cathode,and the catalytic performance of each cathode were compared.The three air cathodes were characterized by SEM,BET and LSV to observe the morphology,pore structure and electrochemical properties.Moreover,the power generation and capacity of H₂O₂production were compared.The results showed that the activated carbon cathode had the best electrical performance,and its maximum power density reached 1016.95 m W/m~2.The graphite cathode achieved the highest production of H₂O₂ of 19.78 mg/L.The results proved that the four-electron reduction of O₂was mainly carried out in the activated carbon cathode,while the two-electron reduction of O₂ was mainly carried out in the graphite cathode.This may be attributed to there are abundant microporous structures in the activated carbon cathode,which can provide more ORR sites for O₂.In contrast,there were few pores in graphite cathode,and most of them were macroporous and mesoporous.Meanwhile,the ratio of graphite to PTFE in graphite air cathode was optimized to improve production of H₂O₂.The results showed that when the ratio of graphite to PTFE was 5:1,the catalytic performance was the best.Howerver,the graphite on the G5 cathode was easy to fall off,which was not conducive to practical application.Therefore,the mass ratio of graphite to PTFE in the air cathode in subsequent experiments was 3:1.（2）The influences of electrolyte concentration,initial pH value,hydraulic condition and external resistance on hydrogen peroxide production and electrical performance of al-air battery were investigated.The experimental results showed that when the concentration of Na Cl solution increased from 1 g/L to 10 g/L,both the power generation and H₂O₂ production of the battery were improved.The initial pH value was also an important factor.The cell achiverd the highest yield of H₂O₂ at pH 3,while the best electric performance was achived at pH 1.Because when the initial pH value was 1,side reactions were mainly carried out in the battery,and H₂O₂ was seldom generated.The hydraulic condition has little influence on the battery’s electric performance,but it will affect the H₂O₂ production.The higher the hydraulic circulation flow rate was,the lower the H₂O₂ yield was.The external resistance has a great influence on the H₂O₂ production.The H₂O₂ production will be higher with the decrease of the external resistance.In conclusion,the cell have the highest H₂O₂production in the optimal conditions at 10 g/L Na Cl solution,initial pH of 3,external resistance of 10Ω,and static hydraulic condition.At this time,H₂O₂ concentration reached 127.07 mg/L after 24h.（3）Fe²⁺was added to the battery to study the removal effect of TC under different parameters including hydraulic conditions,electrolyte concentration,Fe²⁺concentration,initial TC concentration,and external resistance.The experimental results showed that:hydraulic conditions had a certain influence on the removal rate of TC,the removal effect of TC was better with the increase of hydraulic circulation flow;The removal rate also increased accordingly with the increase of Na Cl solution concentration;The effect of Fe²⁺concentration on TC removal rate was complicated.With the Fe²⁺concentration increases from 0 to 25mg/L,the removal rate of TC increaseed significantly.However,the removal rate decreased while the Fe²⁺concentration continued to increase to 50 mg/L;When the initial concentration of TC increased from 10 mg/L to 50 mg/L,the removal rate decreased accordingly;With the reduction of external resistance from 100Ωto 10Ω,the removal rate increases obviously.In the open circuit,the removal rate of TC was very low.（4）The mechanism of removal of TC of al–air fuel cell was explored by radical capture experiment.The results showed that the removal rate of TC in the experimental group with isopropanol was similar to that without Fe²⁺,and was significantly lower than that in the experimental group with Fe²⁺.The removal rate of TC in the former was only 87%,while that in the latter was above 99%.This phenomenon indicated that the removal of TC was attributed to two points:one was degradation of·OH;The other was the flocculation.In which,·OH play a major role.·OH can degrade TC into non-toxic and harmless small molecules,while flocculants can only remove TC through physical action.