Study On Electrochemical Degradation Of Antibiotic Organic Matter

The large-scale use and even abuse of antibiotics have caused the ecological environmental pollution and ecological toxicological effects of antibiotics,which has become one of the major environment problems for China and the world.Invisibly,it also increased human health risks and greatly increased the risk of outbreaks of epidemics.Because antibiotics are relatively low in biodegradability,traditional water treatment methods do not completely remove antibiotics from the environment,and people began to explore efficient methods for degrading antibiotics.Therefore,it was difficult to establish a safe,controllable and non-secondary pollution degradation method to treat antibiotic wastewater.In this paper,electrochemical method was selected to degrade oxytetracycline hydrochloride and tetracycline hydrochloride.The factors affecting the degradation process,degradation products,degradation pathways and degradation kinetics were studied.The following conclusions are drawn as follows:（1）Three kinds of DSA plates coated with Ti as the base of IrO₂ were selected and characterized by SEM,EDS and electrochemical tests.They all showed"crack"structure and fromed regular grid structure on the surfaces.The Ti/Ta₂O₅-IrO₂ anode plate and Ti/Ta₂O₅-SnO₂-IrO₂ anode plate had higher Ir content,higher OEPs,and better electrochemical degradation performance.（2）The detection method of oxytetracycline hydrochloride and tetracycline hydrochloride were established,and the method was met the demand of the Guidelines for Verification of 9101 Pharmaceutical Quality Standard Analysis Method in terms of specificity,linearity and repeatability,and could accurately determine the contents of oxytetracycline hydrochlorideand tetracycline hydrochloride.（3）The electrochemical degradation of oxytetracycline hydrochloride was studied by single factor experiment and orthogonal experiment.The best anode plate was Ti/Ta₂O₅-IrO₂.The optimal conditions were as follows:current 0.400 A,the plate spacing 2 cm,the electrolyte Na₂SO₄ concentration 4 g/L,the solution pH 3.The influence of degradation effect was as follows:current intensity>electrolyte concentration>solution pH>plate spacing.The reaction was consistent with the first-order kinetic reaction.（4）The electrochemical measurements of oxytetracycline hydrochloride showed that the indirect reaction of oxytetracycline hydrochloride on Ti/Ta₂O₅-IrO₂ plate is the main one.It was a typical diffusion-controlled electrochemical process.The degradation products of oxytetracycline hydrochloride were identified by LC-MS and the changes of TOC,pH during the degradation process.It was inferred that seven possible compounds might be electrochemical degradation products.Five possible degradation pathways were proposed.（5）The electrochemical degradation effect of tetracycline hydrochloride and its kinetics were studied.When Ti/Ta₂O₅-IrO₂ plate was used as the anode plate,the degradation efficiency of tetracycline hydrochloride was 68.55%.The optimal experimental conditions obtained by single factor were as follows:current intensity0.65A,plate spacing 2 cm,electrolyte Na₂SO₄ concentration 5 g/L,solution pH 7.The degradation reaction conformed to the first order kinetics.The regress function,a library function of MATLAB 7.0,was used to fit 13 groups of random reaction results and obtained the rate constant formula as follows:（?）It could be seen that the order of the four factors affecting the degradation efficiency was current intensity>solution pH>electrolyte concentration>plate spacing.The results of two groups of experiments showed that the model could accurately describe the process of electrochemical degradation of tetracycline hydrochloride.