Research In The Protective Effect And Mechanism Of Silane Emulsion On Cement Based Materials Biofouling In Marine Environment

Many large concrete structures such as docks,oil platforms,pipelines and cooling towers need to be exposed to sea water for a long time and are easily corroded by different types of microorganisms.These microorganisms can produce organic or inorganic acids that can dissolve and decompose concrete,attack the surface of concrete and its pores and micro-cracks,and cause irreversible damage to concrete through biological fouling.Therefore,how to inhibit the growth and formation of microorganisms and biofilms on the concrete surface is of great significance for controlling the biological fouling of the concrete surface and improving the anti-fouling and anti-corrosion effect of the concrete.This project firstly constructed TEOS/IBTS composite coating and GO/IBTS composite coating on concrete surface based on ethylene orthosilicate(TEOS)/isobutyltriethoxysilane(IBTS)composite emulsion and graphene oxide(GO)/isobutyltriethoxysilane(IBTS)composite emulsion developed by the group in the previous stage,and conducted Illumina Mi Seq high-throughput sequencing was performed to understand the colonization process of microorganisms on the concrete surface and to explore the effects of composite coatings on the microbial community and functional microorganisms on the concrete surface.In addition,the laser confocal microscope(CLSM)was used to analyze the anti-adhesion performance of the composite coating to microorganisms and the inhibition of the microbial film.Secondly,a nano-silver aqueous solution with excellent bactericidal effect was developed as a precursor,and a new type of nano-composite coating—nano silver/isobutyltriethoxy silane(IBTS)composite emulsion was prepared,which had both IBTS The excellent waterproof effect of the emulsion and the efficient sterilization performance of the nano-silver aqueous solution.Finally,the test blocks coated with IBTS emulsion,TEOS/IBTS composite emulsion,GO/IBTS composite emulsion and nano-silver/IBTS composite emulsion are subjected to ocean tidal zone exposure test and static seawater environment immersion test,and systematic research the anti-fouling and anti-corrosion effects of different composite coatings on cement-based materials,and the related protection mechanisms are discussed.Based on the above content,the main research results are as follows:(1)Perform Illumina Mi Seq high-throughput sequencing of microorganisms on concrete surfaces coated with TEOS/IBTS composite emulsion GO/IBTS composite emulsion.Its shown that the number of OTUs on the surface of concrete coated with TEOS/IBTS composite emulsion and GO/IBTS composite emulsion was lower than that of the uncoated test block.At the same time,the Chao value and Ace value of the bacteria on the concrete surface were reduced,indicating that the composite coating wasnot only can reduce the amount of microorganisms attached,and iwas not conducive to the growth and reproduction of microorganisms.In addition,the composite coating effectively reduced the adhesion of bacteria that cause concrete corrosion,such as Desulfobacterota and Firmicutes,and significantly improved the bacterial community structure on the concrete surface.CLSM results showed that the composite coating has excellent anti-cell adhesion properties,inhibits the formation of microbial membranes,and reduces surface biofouling.(2)The systematic characterization of the nano-silver aqueous solution verified the existence of nano-silver particles,and Ag⁺occupied the majority,and Ag⁺was the main cause of sterilization,indicating that the prepared nano-silver aqueous solution had effective sterilization performance.FTIR analysis found that the Si-O-Si characteristic peak at the junction of cement-based material and silane appeared at 1111 cm^-1,and the valence bond structure of silane and cement-based material was linked.At the same time,nano-silver induced the production of linear polysilane,indicating that the nano-silver/IBTS composite emulsion was successfully combined with the surface of cement-based materials.Through SEM observation,it was found that the surface of the test block coated with nano-silver/IBTS composite emulsion is relatively denser,and a stronger coating structure was constructed on the surface of the cement-based material.In addition,the sterilization rate of water samples added with nano-silver aqueous solution can reach more than 98%,and the surface of the test block coated with nano-silver aqueous solution and nano-silver/IBTS composite emulsion has the highest red fluorescence intensity,indicating that both had excellent sterilization performance.Through the contact angle test,the surface contact angle of the cement paste coated with the composite emulsion is 106.07°,indicating that the surface has a certain hydrophobic effect.(3)The test blocks coated with the four composite emulsions were placed in the tidal area of Qingdao's Wheat Island for a real sea exposure test.It was found that the surface corrosion of the test blocks coated with the composite emulsion was relatively light,there was no visible biological attachment on the surface,the mass loss rate was always lower than that of the uncoated test block,and the p H was always higher than that of the uncoated test block.XRD analysis showed that the characteristic peak intensity of Ca CO₃was significantly reduced,indicating that the composite coatings can effectively improve the anti-carbonization performance of the cement-based material surface.In addition,the contact angle of the test block coated with the composite emulsion is always greater than 90°,which is higher than that of the blank group,and its long-term hydrophobic performance can be guaranteed;And after 90 days of exposure,the surface of the test block coated with the composite emulsion did not form a large area of biofilm.Compared with the blank group,the microbial distribution was less and sparse,the surface anti-cell adhesion performance was also improved,and the surface of the test block was dense.The high density and compactness indicate that the composite coating improves the anti-corrosion performance and anti-fouling performance of cement-based materials in the marine environment.(4)The corrosion condition of the test block in static seawater environment was lighter than that in the ocean tide area.The four composite coatings in the static seawater environment have better protective effects than those in the ocean tide area,whether it was anti-carbonization effect or anti-p H Anti-corrosion and anti-fouling performance such as reduction performance,hydrophobic performance,and anti-cell adhesion performance are all better,which shows that hydrodynamic factors(natural factors)and microorganisms have a certain influence on the protection of composite coatings,and the four composite coatings The layer was also suitable for the environment in the ocean immersion area,and can play an excellent protective role.(5)Overall,TEOS/IBTS composite coating and GO/IBTS composite coating have the most excellent protective effects,followed by nano silver/IBTS composite coating and IBTS coating.Among them,nano silver/IBTS composite coating has a certain effective bactericidal performance.