Study On The Photocatalytic Degradation Of Antibiotic-copper Complex

With the rapid growth of antibiotics and metals contamination in environmental,the combination risk of antibiotics and heavy metal ions pollution has continuously growing,especially tetracyclines,sulfas and quinolones.Antibiotics can be compounded with metal ions,because that there are many electron donor groups（carboxyl,hydroxyl,amino,etc.）and heteroatoms（N,O,S,etc.）in the structure.Complex pollutants formed by antibiotics and metals bring new environmental problems.In order to remove such composite pollutants effectively,the feasibility of the treatment method of composite pollutants needs to be further explored.In this article,tetracycline（TC）,sulfamethazine（SMT）,ciprofloxacin（CIP）and copper ion(Cu²⁺)were selected as research objects,and the possibilities and mechanisms of Antibiotic-Cu by photocatalytic technology was studied.Bi₂Mo O₆/Bi₂S₃ heterojunction were synthesized by solvothermal method,using tetracycline（TC）and copper ion as targets,the effect of photocatalytic degradation of TC-Cu was studied by Bi₂Mo O₆/Bi₂S₃.The effects of the mass ratio of Bi₂Mo O₆ to Bi₂S₃,the initial of p H,the initial concentration of TC and the molar ratio of TC to Cu²⁺on the degradation deficiency of TC were investigated.The main active free radicals of Bi₂Mo O₆/Bi₂S₃ photocatalytic degradation of TC-Cu were identified through free radical capture experiments.And the degradation products were detected by HPLC-MS to explore the degradation path and mechanism.The results showed that the degradation rate of TC in TC-Cu complex is higher than that of pure TC,and neutral conditions were favorable for photocatalytic degradation of TC in complex;the MS-0.3heterojunction（the mass ratio of Bi₂Mo O₆ to Bi₂S₃ was 3/1）has the strongest catalytic activity;When the concentration of TC is 10 mg/L,the degradation rate and mineralization rate of TC are 85.63%and 61.82%,respectively,after 60 minutes reaction;Under the same conditions,for the TC-Cu complex with a molar ratio of TC to Cu²⁺was 2/1,the degradation rate and total organic carbon removal rate change,which are 88.24%and 52.94%,respectively.The results of the active group capture experiment showed that the·O₂^-plays the major role in the visible light catalytic degradation.The toxicity of the photocatalytic degradation process was evaluated by the growth inhibition rate experiment of chlorella.The results of the growth inhibition rate experiment showed that TC and Cu²⁺had a synergistic effect on the growth inhibition of chlorella;Compared with the degradation process of TC,TC-Cu complex did not produce more toxic products.The flower like Bi OCl/Ti O₂ heterojunction was synthesized by the solvothermal method.Using tetracycline（TC）and metal ion copper as targets,the effect of copper ion(Cu²⁺)on photocatalytic degradation of TC was studied by photocatalytic technology.The effects of p H,initial concentrations of TC and the molar ratio of TC and Cu²⁺on photocatalytic performance were investigated.Meanwhile,the results indicated that the photocatalytic degradation of TC showed better photocatalytic performance in neutral conditions and TC-Cu showed better photocatalytic performance than TC;When the p H was 7,the concentration of TC was 20 mg/L,the degradation rate and mineralization rate of TC were 84.21%and 47.49%,respectively,after 60 minutes reaction;Under the same conditions,for the TC-Cu complex with a molar ratio of TC to Cu²⁺was 2/1,the degradation rate and total organic carbon removal rate change,which were 89.14%and 40.10%,respectively.In addition,the toxicity of degradation products was evaluated by the growth inhibition rate of chlorella.The results of toxicity test showed that the TC-Cu complex could be effectively degraded by Bi OCl/Ti O₂.The chlorella was used to evaluate the toxicity of degradation products,it was found that TC and Cu²⁺showed a synergistic effect on the growth inhibition of chlorella.The initial TC-Cu complex inhibited the growth of chlorella higher than TC.However,the growth inhibition rate of TC-Cu degradation products was lower than that of pure TC degradation products.The Bi OCl/Ti O₂ heterojunction was selected as photocatalytic material,sulfamethazine（SMT）,ciprofloxacin（CIP）and copper ion as targets,the effect of SMT-Cu and CIP-Cu on photocatalytic degradation of was studied.The effects of p H,the initial concentration of SMT/CIP and the molar ratio of SMT/CIP to Cu²⁺on the degradation deficiency were investigated.The results showed that When the p H was 7,the concentration of SMT was 10 mg/L,and the molar ratio of SMT and Cu²⁺was 1/1,the removal rate of SMT in SMT-Cu was 75.89%,and the mineralization rate was6.21%;Under the same conditions,the removal rate and mineralization rate of SMT were 89.81%and 23.80%,respectively.When the p H was 7,the concentration of CIP was 10 mg/L,CIP and Cu²⁺molar ratio was 2/1,the degradation of CIP in CIP-Cu was99.83%and the mineralization rate was 21.46%.At the same time,the degradation and mineralization rate of pure CIP were 98.78%and 28.20%,respectively.The toxicities of SMT/CIP and SMT/CIP-Cu before and after degradation were evaluated by the chlorella growth inhibition experiments.It was found that Cu²⁺can enhance the growth inhibition of chlorella by SMT and CIP,and the growth inhibition of products during the degradation of SMT-Cu and CIP-Cu was lower than that of the original solution.