Uitrasonic Degradation Of Ciprofloxacin In Simulated Aquzculture Wastewater

Due to the large usage, frequently detection in aquacultureaquatic and biodegradation difficulity, ciprofloxacin, one of quinolonesantibiotics was selected as the research object.Combined with the feature of antibiotics and heavy metals compound pollution water.Simulation the characteristics of coexisting substance in the aquaculture wastewater.According to discharge standard of pollutants forlivestock and poultry breeding?GB18596-2001?. CODcr?400 mg/L, Ammonia nitrogen?80 mg/L. Based on hydroxyl radical and sulfate radical anion mechanism. The effects of heavy metal on the degradation of ciprofloxacin by ultrasound was investigated. The main contents included:?1? The degradation of ciprofloxacin was studied based on hydroxyl radical. Degradation of ciprofloxacin by Cu²⁺ catalyzed US/H₂O₂, Cu²⁺-Fe²⁺catalyzedUS/H₂O₂. The results indicatedthat Cu²⁺ could effectively catalyziedthe US/H₂O₂in the degradation of ciprofloxacin.The initial concentration of ciprofloxacin was3mg·L^-1,pH=6.9, the adding amount of H₂O₂15mmol·L^-1, ultrasonic power 195 W,60 min, degradation rateof ciprofloxacin reached 88.3%.Cu²⁺-Fe²⁺ as two kinds of catalysts can effectively catalyze US/H₂O₂ in degradation of ciprofloxacin.The addition ratio of Cu²⁺, Fe²⁺ and the initial pH value of solution had great effect on the degradation. The adding concentration of Cu²⁺,Fe²⁺ were 5.0mg·L^-1 , 7.5 mg·L^-1,other conditions are the same, 60min, optimum degradation rateof ciprofloxacin reached 95.35%. The pseudo-first-order rate constant of ciprofloxacin degradationk reached a maximum of 47.13×10-3min^-1.NO₂^-, NO₃^-, NH₄⁺ and their coexistence form, COD in influencing the degradation effects of ciprofloxacin also effective removal. NO₂^-inhibitedthe ultrasonic degradation rate. Degradation of ciprofloxacin by Cu²⁺ catalyzed US/H₂O₂, the adding concentration of N02" were 80mg·L^-1, ultrasonic reaction 60 min of ciprofloxacin the degradation rate is only 2.9%. NO₃^- acceleratedthe ultrasonic degradation rate and NH₄⁺ had little effect on it. COD significantly inhibited the removal of ciprofloxacin, and the removal rate of ciprofloxacin decreased with the increase of COD concentration. In the process of degradation reaction of ciprofloxacin, NO₂^-, NO₃^-, NH₄⁺ have different degree of removal effect,reaction 60 min, removal rates were 70.03% ?48.04% and 20.10%. COD concentration decreased with the reaction, with the concentration of COD increased in the range of 0.0?150 mg·L^-1, removal efficiency of COD decreased. The concentration of citric acid increased in the range of 2.0?4.0mg·L^-1. the degradation effect of ciprofloxacin increased with the increase of concentration. The additive concentration was 6.0mg·L^-1, the degradation effect of ciprofloxacin decreased.Free radical quenching experiments show that hydroxyl radicals·OH plays a main role in the Cu²⁺ catalytic US/H₂O₂ degradation of ciprofloxacin process. The effect of inorganic nitrogenis the production of ·OH in the system.?2? The degradation of ciprofloxacin was studied based on sulfate radical. Degradation of ciprofloxacin by Cu²⁺ catalyzed US/K₂S₂O₈, Cu²⁺-Fe²⁺ catalyzed US/K₂S₂O₈.The experimental parameters such as nitial concentration of ciprofloxacin, pH value, adding amount of K₂S₂O₈ and Cu²⁺, Fe²⁺, effects of inorganic nitrogen, organic acid and COD on the degradation of ciprofloxacin were evaluated.The results indicatedthat compared with US/K₂S₂O₈,the introduction of Cu²⁺ can effectively enhance the degradation of ciprofloxacin. The initial concentration of ciprofloxacin was 3mg·L^-1, pH=6.9, the adding amount of K₂S₂O₈ 0.4g·L^-1,ultrasonic power 195W, 60 min, degradation rateof ciprofloxacin reached 88.47%. Cu²⁺-Fe²⁺ as two kinds of catalysts can effectively enhancedegradation of ciprofloxacin .The adding concentration of Cu²⁺, Fe²⁺ were 4.0mg·L^-1, 4.0mg·L^-1, 60 min, removal rate increased to 91.49%. The presence of NO2 , NO₃^-, NH₄⁺ and COD affect the degradation of ciprofloxacin.Low concentration of NO₃^- inhibited the degradation of ciprofloxacin,while higher concentration of NO₃^- promoted degradation. With the NO₃^- concentration increased,ciprofloxacin degradation rate also decreased gradually in O.Omg·L- 1?60mg·L^-1,from 88.47%reduced to 44.99%, N03- concentrations increased to 80 mg·L^-1 , other conditions are the same,removal efficiency of ciprofloxacin increased to 89.37%. NO₂^- inhibitedthe ultrasonic degradation rate and NH₄⁺ had little effeet on it. Methanol alcohol to add shows that SO4-. are the main active species. The effect of inorganic nitrogenis the production of SO4-. in the system.