Application Of Immobilized Enzymes Epoxy Composite Coatings In The Circulating Cooling Water System

Heat exchanger corrosion,microbial breeding and other issues are existing in circulating cooling water system among refining enterprises.In order to control the corrosion of heat transfer equipment,the measure of adding corrosion inhibitor and sterilization algae usually will be taken to control the corrosion ions and microorganisms,but these pharmaceutical properties will be affected by leakage of materials,and excessive use of chemicals discharged into the environment will cause secondary pollution.In addition,surface coating protection is also an effective way to control metal corrosion.In recent years,with the enhancement of environmental awareness,traditional metal coating protection or surface treatment methods are being challenged,so we need to seek new environmentally friendly surface coating technology.In this paper,a green and environmental bio-enzyme coating was studied to broaden the application of immobilized enzyme inhibitors,three new anti-corrosion coatings were prepared,nano-silica modified epoxy composite coating,immobilized lipase/epoxy composite coating and immobilized lysozyme/epoxy composite coating.First,the epoxy composite coatings with different nano-SiO₂ content were prepared and analyzed by analysis the characterization and dispersion of nano-SiO₂.Then the immobilized lipase/epoxy composite coating and immobilized lysozyme/epoxy composite coating were prepared by immobilizing lipase with SiO₂ as carrier,and the performance of the composite coating was analyzed by changing of immobilized amount of immobilized lipase and immobilized lysozyme.Finally,the prepared immobilized lipase/epoxy composite coating,immobilized lysozyme/epoxy composite coating and single epoxy coating were tested by the durability experiment respectively.Specific experimental conclusions are as follows:The hardness of epoxy composite coating could reach 3H,the adhesion reached 1,when the content of nano-SiO₂ particles was 1%⁴%,this concentration range allows the hardness and adhesion of the epoxy composite coating to be kept in the best condition.Through electrochemical test,the capacitive loop reached the maximum and anti-corrosion performance was the best when nano-SiO₂ content of epoxy composite coating was 2%.The hardness of the coating were the best when adding 2%mass fractions immobilized lipase.The adhesion of the coating was the best when adding 1%mass fractions immobilized lipase.The hardness and adhesion of the coating increased with the mass fractions increasing of immobilized lipase in the coating.The anti-corrosion effect of the coating reached the best when adding 2%mass fractions immobilized lipase.The anti-corrosion effect of the coating reached the best when adding 1.5%mass fractions immobilized lysozyme.Immobilized lipase/epoxy composite coating could maintain 48h anti-corrosion properties,Immobilized lysozyme/epoxy composite coating could maintain 24 hours anti-corrosion properties,and the resistance value of the single epoxy coating decreased obviously after 8 hours of immersion.And the corrosion rate of the metal under the protection of the composite coating with immobilized lipase or lysozyme was lower than that of the metal under the protection of a single epoxy coating.The anti-corrosion effect of the enzyme epoxy composite coating decreased with the increasing of immersion time.The lysozyme coating corrosion resistance was better than that of lipase coating when immersion time was less than 10 days,The lipase coating corrosion resistance was better than that of lysozyme coating when immersion time was more than 10days.After 30 days of immersion,the corrosion inhibition capacity of the single epoxy coating was greatly reduced,while the lysozyme coating and the lipase coating still had a high corrosion inhibition capacity,indicating that the presence of biological enzymes could improve the anti-corrosion properties of epoxy coating.