Degradation Of Tetracycline Hydrochloride By Three Dimensional Electrochemical System With Transition Metal Doped Activated Carbon

At present,the rapid development of society has caused a series of water environmental pollution problems,especially the emerging organic pollutants such as antibiotics,which has become a hot issue in the environmental field.Tetracycline hydrochloride is widely used in medicine,animal husbandry and other industries,its presence in the environment will lead to some microbial resistance,increase microbial toxicity,at the same time will harm human health has caused damage to the ecological environment,and then cause a series of environmental pollution problems.Compared with maternal antibiotics,the generation of microbial resistance genes will cause greater risks to the environment,endanger human health and damage the ecological environment.Three-dimensional electrochemistry is seen as the most promising and greener way to dispose of antibiotics.The selection of particle electrode material is the key to the treatment effect of 3D electrochemical technology,which determines the degradation path and degradation degree of organic pollutants.Granular activated carbon has been widely used in the field of three-dimensional particle electrode materials because of its large specific surface area,strong adsorption capacity and good conductivity.In this thesis,tetracycline hydrochloride（TCH）was decomposed by doping the transition metal iron,copper and manganese into activated carbon,and filling the particle electrode of iron,copper and manganese trimetallic doped activated carbon（FMC-AC）into a new three-dimensional electrode model（N3D-FMC-AC）.The results are as follows:（1）A granular activated carbon electrode was prepared by the impregnation method.The degradation of granular activated carbon electrodes was evaluated by TCH.The experimental results showed that the prepared granular activated carbon showed the best degradation performance under the conditions of an immersion time of 12 h,a roasting temperature of 850°C,and a roasting time of 3 h.（2）The effects of different metal loads on TCH simulated wastewater were discussed.The experimental results show that the degradation effect of granular activated carbon on TCH is best when the ratio of load concentration is Fe:Mn:Cu=0.5 mol/L:0.5 mol/L:0.5 mol/L.By scanning electron microscopy（SEM）analysis,the FMC-AC particle electrode showed crystal formation.X-ray diffraction（XRD）and X-ray energy dispersion spectroscopy（XPS）determine the successful loading of Fe,Cu,and Mn.The specific surface area test（BET）showed that the loaded activated carbon showed a higher specific surface area.（3）A novel three-dimensional electrochemical reactor（N3D）was designed and compared with the traditional three-dimensional electrochemical method.The anode plate used in the experiment is a double-coated Ru-Ti-tin electrode（Ti/Ru O₂-Ti O₂-Sn O₂ plate,100 mm x 50 mm x 1 mm）,the cathode is a stainless steel square groove（70 mm x 70mm x 100 mm）,the aperture is 2 mm,and the anode plate is vertically placed in the middle of the stainless steel square groove.The activated carbon particle electrode is added into the stainless steel square tank and distributed uniformly around the anode,so that the particle electrode is evenly distributed between the anode and the cathode.The particle electrode has double polarity in each direction,which can effectively enhance the mass transfer efficiency.（4）Response surface curve method（RSM）was used to optimize the degradation conditions of tetracycline hydrochloride（TCH）.Using the Design-Expert response surface analysis software,quadratic polynomial fitting was carried out on the data obtained from the experiment.After fitting the regression equation,the regression equation of TCH degradation rate and current intensity（A）,electrolyte concentration（B）and solution p H value（C）during the experiment was obtained.TCH degradation rate（%）=95.56+4.60 x A+0.79 x B-0.16 x C+0.20 x A x B+1.15 x A x C-1.62 x B x C-3.74 x A²-3.72 x B²-5.37 x C².When the current intensity was 0.72 A,the p H was 7.07,and the concentration of electrolyte（Na2SO4）was 0.11 mol/L,the degradation effect reached 97%.The degradation process of TCH was analyzed by kinetic analysis.The results showed that the degradation process of TCH was consistent with the first-order kinetic model.The main free radical degraded by TCH was determined to be·OH by EPR and free radical quenching experiments.The TOC experiment demonstrates that the model developed in this experiment is capable of mineralization.The degradation products were analyzed by HPLC-MS,and 11 degradation products were inferred and three degradation paths were given.Toxicity assessment software（T.E.S.T.）predictions were used to assess the ecotoxicity of TCH and its intermediates in terms of degradation,acute toxicity,bioaccumulation factors,developmental toxicity,and mutagenicity.The results show that the novel three-dimensional electrochemical reactor can reduce the toxicity of TCH,but a few degradation intermediates are still toxic.（5）After repeated use of activated carbon particle electrodes,the degradation effect of TCH became worse.To solve this problem,the activated carbon was treated with thermal regeneration.The regenerated activated carbon particle electrode was analyzed by SEM,XRD,XPS,and BET,and the degradation effect of TCH was evaluated.The experimental structure showed that the regenerated activated carbon particle electrode still showed a good effect on the degradation of TCH.