Mechanism of inhibition of iron corrosion in HCl by acetylenic alcohols

Abstract

Introduction The mechanism of the inhibition of the corrosion of iron in HCl by acetylenic alcohols, is investigated by weight change method, galvanostatic method and faradic impedance method. Propargyl alcohol offers greater protection than 3‐butyn‐2ol, 2‐methyl‐3‐butyn‐2‐ol and 2‐butyn 1,4 diol in hydrochloric acid solution of concentrations (1.0 to 8.0M). The corrosion of pure iron in hydrochloric acid solutions involves the participation of adsorbed FeOH intermediate and forms chlorhydroxy iron complex. The addition of ferrous ion is found to favour the three‐dimensional chelation with inhibitor molecule, leading to polymen film formation. With prolonged exposure the thickness of the polymer film increases.

Acid‐Responsive Anticorrosion Microcapsules for Self‐Protecting Coatings

“…The increased inhibition is attributed to the enhanced passivation offered by BD due to the 𝜋electron interaction between the triple bond and metal surface. [36] Demonstration of acid-triggered response of the capsules within a coating is also shown in the Supporting Information (Figures S21 and S22, Supporting Information) through 1 H NMR studies of phenolic epoxy coatings loaded with butyne di-OTMS microcapsules and exposed to acidic aqueous conditions. The results show that the capsules retain their pH-responsive behavior within a coating environment.…”

“…The IE is indicative of the anticorrosion performance of the selfprotecting coating through the reduction in corrosion current. acidic solutions in the presence of BD [36,37,44] and JJB [45] are well understood, and hence Tafel analysis was performed merely to quantify the self-protecting capabilities of the coating…”

“…Acetylenic alcohols and JJB are known to be strong organic corrosion inhibitors in acidic solutions. [35][36][37][38] These molecules chemisorb on the metal substrate to form protective films. [36] Ketal-based polyamide microcapsules were previously shown to be used for pH-responsive drug delivery.…”

“…[35][36][37][38] These molecules chemisorb on the metal substrate to form protective films. [36] Ketal-based polyamide microcapsules were previously shown to be used for pH-responsive drug delivery. [33,34] The cross-linked polyamide shell wall and the responsiveness of the ketal moiety to mild acidic conditions (pH < 6) make this polymer attractive for anticorrosion applications.…”