Achieving high loading inhibitor carriers with pH-response for active corrosion protection using attapulgite

Abstract

A new pH-response inhibitor self-healing anticorrosion coating containing attapulgite (ATP) that inhibits 1-allyl-3-octylimidazolium bromide (expressed as ATP@IL) has been developed. This inhibitor carrier can store 28.6 wt% weight of inhibitor. When ATP@IL was added into 0.5 M H2SO4 solution, the inhibition efficiency reached 99.8% (steel corrosion rate is reduced to 0.2%). The Rct of ATP@IL increased by 59.5% compared with pure IL and increased by 99.97% compared with pure ATP, evidence of an excellent inhibition efficiency. Furthermore, this material was added to a water-based epoxy resin (EP) to synthesize a self-healing coating (ATP@IL/EP), resulting in excellent anti-corrosion performance due to the pH-response releasing of inhibitive material. The inhibitors are adsorbed on the surface of the steel substrate, forming a sustainable protective film to prevent the contact of metal and corrosive medium. Electrochemical tests indicated that this new coating with pH-triggered self-healing property possessed a much longer time protective ability compared to the common epoxy resin coatings with ATP. The EIS data illustrated that the impedance of ATP@IL/EP coating was above 108 Ω cm2 after 40 days, which was two orders of magnitude higher than the EP coating. This meant ATP@IL could further improve the protective ability compared to the ATP.