Preparation Of CoP_xO_y Composites With Highly Effective Broad-spectrum Antibacterial Activities And Their Inhibition Of Microbiologically Influenced Corrosion

Recently,due to the increasing national development and utilization of marine resources,more and more metallic materials have been used for the constructions of marine equipment and engineering.However,the marine environment is complicated and harsh,and the marine metallic materials usually face a big concern of serious microbiologically influenced corrosion,which can not only greatly limit the development and utilization of marine resources,but also endanger people’s life and property security.Thus,the research on microbiologically influenced corrosion and anti-microbiologically influenced corrosion strategy are very important for the protection of metal materials in the marine environment.In an open system or the environment that is not suitable for use of inhibitors,an ideal,feasible,and effective way is to use antibacterial to inhibit microbiologically influenced corrosion.In light of literature researches,in this work we developed the lamellar Co P_xO_y composite oxides by using a simple co-precipitation,which showed great anti-bacterial and anti-fungal activities.By using characterization technologies such as SEM,XPS,XRD,there is a strong interaction between Co and P elements in the Co P_xO_y oxides,and the Co P_xO_y composites show excellent stability.On basis of this,the following two parts of this work have been carried out:In the first part,we tested the antibacterial activities of the series of CoP_xO_y composites with different Co/P ratios.The antimicrobial activities of as-prepared Co P_xO_ycomposites against four microorganisms（bacteria:Escherichia coli and Pseudomonas aeruginosa;fungi:Candida parapsilosis and Candida albicans）were tested by the disk agar diffusion method（DAD）.This result showed that the antibacterial activity of Co P_xO_ycomposite oxide against bacteria was better than fungi,and moreover,the optimal antibacterial activity against Pseudomonas aeruginosa was the best in this work.In addition,the antibacterial activity of Co P_xO_y composites has been obviously related to the Co/P molar ratio.When the Co/P ratio is 1,the as-prepared Co P₁O_y composite oxides present the best antibacterial activity.Meanwhile,Co₃O₄ and NaH₂PO₄（phosphorus source）as reference materials were also tested,it had no antimicrobial properties.This result reveals that the interaction between Co and P in composites may be responsible for the superior antibacterial activity.Following that,the minimum inhibitory concentration（MIC）of the series of materials for these microorganisms was tested and the Co P₁O_y composites show the lowest values of the minimum inhibitory concentration for all microorganisms.The statistical results showed that the minimum inhibitory concentrations of Co P₁O_y against Pseudomonas aeruginosa,Escherichia coli,Candida albicans and Candida parapsilosis were 4.88μg/m L,19.53μg/m L,78.12μg/m L and 312.5μg/m L,respectively.In the second part,we firstly studied the effect of Candida albicans on Ti and Pseudomonas aeruginosa on 5083 aluminum alloy in artificial seawater.The electrochemical test results show that Candida albicans and Pseudomonas aeruginosa can respectively exacerbate the corrosion of titanium and 5083 aluminum alloy in artificial seawater.Then,the prepared Co P₁O_y composite oxide with optimal antibacterial properties was coated on the surface of titanium and 5083 aluminum alloy to study the anti-microbial corrosion and anti-fouling properties of the coating.The electrochemical test results showed that the coating could effectively inhibit the corrosion of metals caused by Candida albicans and Pseudomonas aeruginosa in artificial seawater.On day 1,the inhibition efficiency of coating on microbial corrosion of Ti and 5083 aluminum alloy is78.48%and 97.84%,and on day 7,the inhibition efficiency of coating on microbial corrosion of Ti and 5083 aluminum alloy is 88.29%and 97.28%.Anti-fouling experiments show that Co P₁O_ycomposite oxide coating can effectively inhibit the formation of pseudomonas aeruginosa and Candida albicans biofilms on the metal surface,thus showing the excellent anti-fouling performance.In conclusion,the CoP_xO_y composites prepared by the simple co-precipitation method shows the broad-spectrum antibacterial activities,and it can be used as a high-efficiency anti-corrosion and anti-fouling multifunctional material.This study provides some ideas and insights for the development of multifunctional anti-microbial corrosion coatings.