Heptanoic acid adsorption on grafted palygorskite and its application as controlled-release corrosion inhibitor of steel

This study deals with the anchoring of heptanoic acid (HC7) as a corrosion inhibitor to palygorskite clay mineral originated from High Atlas of Marrakech (Morocco) beforehand grafted with 3-aminopropyltriethoxysilane (APTES) entities. Physicochemical characterizations (XRD, FTIR, TG-MS, zeta potential measurements) confirmed the success of the APTES-grafting to silanol sites of palygorskite fibers edges and the heptanoate anions bonding to terminal NH3+ sites of grafted-APTES. Then, full-factorial design allowed optimizing the conditions of heptanoate adsorption. Preliminary electrochemical measurements revealed that functionalized grafted palygorskite (C7-APTES-Pal) can progressively release the heptanoate corrosion inhibitor in 0.1 M NaCl solution to inhibit the steel corrosion processes.