| Photocatalysis is a green and efficient technology to inactive kinds of pathogenic microorganisms,which is expected to replace the traditional antimicrobial methods and used in water treatment,hospitals and public facility,food and medicine industry,etc.Zinc oxide(ZnO)as an efficient semiconductor photocatalytic antibacterial agent,have many advantages,such as environmentally friendly,biological compatibility,inexpensiveness and efficient broad-spectrum disinfection.However,pristine ZnO can only be exited by UV light to induce superior antibacterial activity,which hinders its practical application.Therefore,to develop visible-light-driven ZnO photocatalytic antibacterial material is of great significance.In this work,iodine modified Zn0(I-ZnO)with visible-light-driven photocatalytic antibacterial activity were prepared by two different methods and the mechanism of photocatalytic antibacterial was studied.Works were conducted as follows:(1)I-ZnO with oxygen vacancies were prepared by solvothermal method and post-calcination treatment.The crystal structure,morphology,light absorption properties of the samples were characterized.In antibacterial experiments,Escherichia coli were used as model bacteria,antibacterial drop-test was carried out to detect the antibacterial activity of materials under visible light irradiation.The effects of defects and reactive oxygen species(ROS)on antibacterial activity of I-ZnO was investigated.(2)I-ZnO-EG and I-ZnO-DG nano materials were synthesis by reflux method.The effects of solvents,reaction temperature,reaction time and calcination temperature on visible-light-driven photocatalytic antibacterial activity was studied.The results show that:(1)pre-I-ZnO prepared by solvothermal method exhibits many bulk defects.After calcination in air at 500 ? for 2 h,many surface oxygen vacancies were conducted on I-ZnO samples.(2)Iodine species of I-ZnO mainly exist in the form of I3-and I5-.Poly-iodides and surface oxygen vacancies were attributed to the visible light response of I-ZnO.(3)The photocatalytic antibacterial activity of I-ZnO is better than that of pristine ZnO and commercial ZnO.Within 4 hours illumination under visible light,the initial bacteria concentration(3.2×106 cfu/mL)was decreased about 5 log by I-ZnO.While at the same condition,the bacteria concentration was decreased less than 2 log by ZnO and commercial ZnO.(4)The scavengers experiments results suggested that·O2-and H2O2 are the main ROS of I-ZnO.Besides,the milled commercial ZnO,which have abundant surface defects,is better than commercial ZnO in photocatalytic antibacterial performance.This indicated that the surface defects of ZnO should play an important role in photocatalytic antibacterial under visible light irradiation.(5)140?-I-ZnO-EG-500?with nanosheets and cage structure were obtained by reflux method,in which ethylene glycol as reactive solution and directing agent,and the reflux conducted at 140? for 4 h,following with 500? calcinations for 2 h.The antibacterial experiments indicated that 140?-I-ZnO-EG-500? samples exhibit excellent antibacterial performance,and the bacteria concentration was decreased about 6 log after 4 hours irradiation by visible light.In addition,the reflux time in the prepared process has little effect on the antibacterial activity of 140?-I-ZnO-EG-500?.(6)Nano structure I-ZnO-DG were prepared by reflux method,in which diethylene glycol as reactive solution.The 140 ?-I-ZnO-4 h-DG-400? sample,which refluxed at 140 ? for 4 hours and then calcined at 400? for 2 hours,exhibits the best antibacterial activity.The bacteria were almost inactivated within 3 hours under visible light irradiation by 140 ?-I-ZnO-4 h-DG-400?.Works in this thesis not only enrich the visible-light-driven photocatalytic antibacterial materials,but also investigate the antibacterial mechanism of I-ZnO materials under visible light.Furthermore,research here is of great significance for the development of visible-light-driven photocatalytic antibacterial materials. |
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