Performance Study On Inactivation Of Marine Microorganisms By Wide Band Gap Photocatalytic Materials

In today’s globalization process,ocean shipping has become one of the most important links to global economic development.However,with the passage of time,the inevitable ballast water treatment and the adhesion of harmful microorganisms in the process of ship transportation have become an urgent problem.Photocatalytic technology is gradually gaining attention because of its low cost,quick effect and no secondary pollution to the environment and can produce oxidized radicals with good inactivation effect.In this paper,the semiconductor photocatalysis technology is applied to solve the marine microbial pollution by using precious metal Ag and narrow band gap BiOI materials to modify the wide band gap ZnWO₄ and BiOIO₃.The broadband gap photocatalysts have broadened the light absorption range,and the composite photocatalysts have improved the separation efficiency of photogenerated electron-hole pairs,which are applied to the treatment of ship ballast water and the improvement of sterilization performance of fluorocarbon resin coatings.The main research results are as follows:（1）ZnWO₄ was prepared using hydrothermal method,followed by photodeposition-reduction method to obtain Ag/AgCl/ZnWO₄ composite photocatalyst.The prepared thin film materials were subjected to inactivation of Chlorella vulgaris under UV light conditions.The results showed that the inactivation time of Chlorella vulgaris was significantly shortened by the modification of Ag/AgCl,and the band gap positions of AgCl and ZnWO₄ were very favorable for the migration and conversion of photogenerated electrons,and the separation efficiency of photogenerated carriers was greatly improved by the addition of Ag.（2）BiOIO₃ was compounded using Ag/AgCl,added to the PEVE coating and compared with the sterilization effect of the different ratios under visible light conditions.After one hour of experimental time,the sterilization rate of the composite material was significantly improved compared to the pure sample.It was found that the surface plasmon resonance effect of metal Ag provides effective active species and can effectively separate photogenerated carriers,providing more active species to inactivate bacteria in seawater.（3）BiOIO₃ and BiOI photocatalysts were prepared by hydrothermal and precipitation methods,respectively,and then BiOI was added to BiOIO₃ by ordinary precipitation at room temperature and used for the modification of fluorocarbon resin coatings.Sterilization experiments were conducted under simulated sunlight irradiation.BiOIO₃ induced the growth of BiOIO₃ and BiOI.And the direct Z-scheme heterojunction formed between the two can effectively reduce the carrier complexation rate and improve the photoresponsiveness.