Preparation And Inhibition Properties For Carbon Steel Of Corrosion Inhibitors Loaded By Micro/nano Containers

In order to cope with the crisis of freshwater and reduce the consumption of freshwater resources,the seawater can be directly used as the cooling medium for the circulating coling system in China’s coastal regions,which has been commonly applied for chemical,metallurgy,power and petrochemical industries etc.However,the corrosion of carbon steel is very serious in seawater environment owing to the high salt content and complex composition of seawater,leading to cause huge economic losses for industrial production.Recently,adding supported corrosion inhibitors into corrosion systems cannot only avoid the premature failure of corrosion inhibitors by contacting with corrosion medium,but also extend the release time of corrosion inhibitors,which is a simple and efficient method to restrain the corrosion of carbon steel.Therefore,developing some novel efficient supported corrosion inhibitors has been research hotspots.In this paper,some supported corrosion inhibitors were prepared by using calcium alginate（Ca-Alg）gel beads,halloysite nanotubes（HNTs）,reduced graphite oxide（RGO）and montmorillonite（MMT）as micro/nano containers.Meanwhile,loading two different corrosion inhibitors into a micro/nano container can make corrosion inhibitors own the high corrosion inhibition efficiency for carbon steel.The release time of corrosion inhibitors can be extended based on the coating effect on the micro/nano containers surface to achieve the purpose of continus release.（1）The Cu-BTA-Ca-Alg gel beads were prepared by piercing-solidifying method followed by freeze-drying technique.The Cu-BTA complex coating can effectively control the release rate of benzotriazole（BTA）such as the low release amount of BTA（<50%at 3600 min）.Considering the internal structure difference of obtained Ca-Alg gel beads by freeze-drying and room temperature-drying techniques,the Na₂MoO₄-Ca-Alg gel beads were prepared using piercing-solidifying followed by room temperature-drying technique.The releasing rate of MoO₄^2-from Na₂MoO₄-Ca-Alg gel beads in aqueous medium is slow such as the low release amount of MoO₄^2-（only 30%at 3000 min）,while high for 3.5%Na Cl（completely release at 3000 min）owing to the ion exchange process.（2）The prepared Ca-Na₂ MoO₄-HNTs by negative pressure method cannot only extend the release time of MoO₄^2-to>600 min,but also exhibit p H response such as high releasing rate of MoO₄^2-in acid environment.In order to enhance the corrosion inhibition efficiency for carbon steel,the high-efficient and p H-responsive Cu-BTA-Na₂MoO₄-HNTs and Cu-BTA-MBT-HNTs were prepared,and exhibited the high released time of corrosion inhibitions（>4000 min）and corrosion inhibition efficiency for Q235 carbon steel（74.26%and 72.70%）from the synergistic effect of different corrosion inhibitors.In addition,the loading amount of corrosion inhibitors for HNTs can be improved by acid treatment,such as the specific surface area from49.685 to 254.940 m²/g and loading amount of 2-seleucid benzothiazole（MBT）from10%to 32%after acid treatment for 32 h,which is attributed to the formation of micropores by the reaction between acid and[AlO₆]in HNTs.（3）The ZnMoO₄/RGO was prepared by hydrothermal method.The loading amount of Zn MoO₄ in ZnMoO₄/RGO can reach 91.59%.Meanwhile,the Zn MoO₄/RGO can exhibit acid and ammonium hydroxide reponse,for example,the releasing rate of MoO₄^2-can be accelerated in acid,alkaline and ammonium hydroxide environment.The corrosion inhibition efficiency for Q235 carbon steel in3.5%Na Cl+Zn MoO₄/RGO can reach 87.25%at 72 h,owing to the formation of inhibition memebrane on carbon steel surface by the synergistic effect of RGO,MoO₄^2-and Zn²⁺.（4）The acid-,alkali-and salt-responsive supported corrosion inhibitor8HQ-MMT was prepared by ion exchange technique.The releasing rate of MoO₄^2-is low in aqueous medium,while high in acid,alkaline and salt medium.