Effect Of Water-soluble Antibacterial Membrane Constructed By Quaternary Ammonium Salt On Fungal Corrosion Of X70 Carbon Steel

There are abundant resources in the ocean,and the use of marine resources requires a lot of construction of marine engineering.However,the ocean is a corrosive and aggressive environment for metal materials.The marine environment not only has a large amount of strong electrolytes,which will cause corrosion of metal materials.And the microorganisms in the ocean may convert ordinary metal corrosion into microbial corrosion.There is a good deal of carbon steel used in marine engineering,which is always corroded.It has caused huge economic losses to the world and also caused pollution to the environment.Therefore,it is urgent to study the inhibition of microbial corrosion of carbon steel materials in the marine environment.At present,the research of microbial corrosion is mainly aimed at metal corrosion caused by bacteria.However,not only bacteria can accelerate metal corrosion,but fungi and algae can also accelerate metal corrosion.Unfortunately,there are few reports on fungal corrosion,and fungal corrosion cannot be ignored.Therefore,the use of environmentally friendly antibacterial materials to slow down fungal corrosion is of great significance to the protection of resources.In this paper,a functional membrane based on quaternary ammonium salts(cetyltrimethylammonium bromide,cetyltrimethylammonium chloride)is constructed on the surface of X70 carbon steel.It is found that the surface of the polished X70carbon steel is hydrophobic,while the surface of the X70 carbon steel constructed with quaternized ammonium salt membrane is hydrophilic.The p H tests show that the metabolites of Trichoderma harzianum(T.harzianum)and Aspergillus niger(A.niger)are acidic,and the CTAB@Fe₃O₄and CTAC@Fe₃O₄membranes could neutrize the acidic metabolites of T.harzianum and A.niger.It is observed by confocal laser scanning microscope that T.harzianum and A.niger could adsorb on the surface of X70carbon steel,and the quaternary ammonium salt membrane could inhibit the adsorption of the fungi on the surface of X70 carbon steel.The electrochemical test results show that T.harzianum and A.niger accelerate the corrosion of X70 carbon steel in artificial seawater solution,and the quaterny-ammonium salt membrane can effectively slow down the corrosion of T.harzianum and A.niger.The quaterny-ammonium salt membrane can more effectively slow down the corrosion of T.harzianum.The antibacterial mechanism is that when the fungus is close to X70 carbon steel,the membrane will release CTA⁺.CTA⁺is combined with the negatively charged phospholipid bilayer of the cell membrane by electrostatic interaction,which affects the normal metabolism of the fungus,and finally hinders the growth and death of the fungus.The anti-fungal corrosion mechanism is that quaternary ammonium salts can inhibit the growth of fungi,thereby reducing the corrosion of X70 carbon steel by fungi;both Trichoderma harzianum and Aspergillus niger are acidogenic fungi.The acidic substances can ionize H⁺.CTA⁺and H⁺repel each other,which slows down the corrosion of acidic substances on metal materials.Therefore,cetyltrimethylammonium bromide and cetyltrimethylammonium chloride can effectively inhibit fungal corrosion.