The Study On Degradation Of Tetracycline Hydrochloride Wastewater By Fenton And Electro-Fenton Reaction

Tetrycycline hydrochloride is a broad-spectrum antibiotic.Due to its strong anti-inflammatory effect and low price,tetrycycline hydrochloride is widely used in the medical industry.It is often used in the animal husbandry or aquaculture industry as a feed additive or disease prevention.Due to people’s wrong cognition of antibiotics and lax prescription drug management,antibiotics are abused,and their residues in the water environment are seriously out of standard.Moreover,tetracycline hydrochloride has a complex structure and is difficult to degrade,causing great harm to human health and the ecological environment.Therefore,the treatment of antibiotics in water environment is urgent.In this experiment,Fenton and electro-Fenton oxidation reactions were used to study the pretreatment of tetracycline hydrochloride production wastewater.The optimal test conditions of the two methods were determined by single factor experiment.Then,Plackett-Burman test was used to screen out the significant single factor affecting the electro-Fenton oxidation reaction for the treatment of tetrahydrochloric acid production wastewater,and Box-Behnken response surface methodology was used to optimize the significant single factor,and the optimal conditions for the single factor having significant influence on the electro-Fenton oxidation reaction were obtained.Finally,on the basis of the optimal test conditions,the removal effect of pollutants,biodegradability and economy were further compared and analyzed,and a more appropriate and feasible pretreatment method was finally selected.Orthogonal tests were carried out on each single factor in the Fenton oxidation system,and the sequence of significance of each influencing factor was obtained as follows:TC initial concentration>the molar ratio of H₂O₂/Fe²⁺>initial pH value>the adding of H₂O₂>reaction temperature.When the reaction temperature was 40℃and pH value is 3,10mmol/L H₂O₂ is added into the reactor,and the molar ratio of H₂O₂/Fe²⁺is 12∶1.The tetracycline hydrochloride aqueous solution with initial concentration of 100μmol/L tetracycline hydrochloride is treated for 60min.After three parallel tests,the TC removal rate is 79.37%.The COD concentration was 111.96mg/L and the BOD concentration was 23.51mg/L.According to Plackett-Burman test,the factors that have significant influence on TC removal rate are:pH>current>electrolyte concentration.Through the Box-Behnken Design analysis of the response surface method,the initial pH and concentration of electrolyte,as well as the current and electrolyte concentration had a significant interaction.Therefore,the optimal degradation process conditions by electro-Fenton oxidation are as follows:Initial pH was 3.2,current was 0.63A,electrolyte concentration was 0.12mol/L,electrolyte concentration was 0.12mol/L,reaction temperature was 30℃,n（H₂O₂）was10mmol/L,when the molar ratio of H₂O₂/Fe²⁺was 16 and the plate spacing between anode（DSA composite electrode）and cathode（graphite）was 2.5cm,three parallel experiments were carried out to verify the TC removal rate was 95.83%,and the experimental results were in accordance with the predicted values.Through comprehensive comparative analysis of Fenton and electro-Fenton oxidation of the removal effect of pollutants,biodegradability,economy.The electro-Fenton oxidation method was superior to Fenton oxidation method in terms of pollutant removal effect and improvement of biodegradability of raw water in the test.However,in terms of economic cost,Fenton oxidation method is more operable.