Nonionic Surfactants as Corrosion Inhibitors for Carbon Steel in Hydrochloric acid Medium

Abstract

The utilization of surfactants is one of the several means for protecting a metallic surface from lectrochemical oxidation or corrosion. The amphiphilic nature of these surfactants encourages the preparation of a self-protective layer on the metallic surface, adequately reducing the area of contact between the liquids and the metal, therefore preventing corrosion. Most of the cationic surfactants like CTAB (Cetyltrimethylammonium bromide) have been utmost frequently used as a corrosion inhibitor of  mild steel in acidic medium, yet since it is not eco-friendly its utilization has been depressed. As a substitute, the utilization of non-ionic surfactants like TritonX100, Tween 20, Tween 80 and Brij 35 which are considerably more eco-friendly were observed as inhibitors in this paper. It is well known that carbon steel is a usual material of construction of various mechanical vessels and equipment’s used in industrial practice which on continuous usage leads to corrosion of material. Here in this paper we investigate that by using nonionic surfactants which are ecofriendly and sustainable as corrosion inhibitors, in interaction with hydrochloric acid (HCL) to deliberate their mechanism of action and how it can be a substitute to cationic surfactants. In this study it is found that the non-ionic surfactants indicated inhibition efficiencies  around 91-92%, which is extremely nearer to that of CTAB (97%) which is cationic surfactant at concentrations of 300-500 ppm with 1M HCL at 30°C. Tween 20 and Tween 80 also demonstrated closer outcomes nearer to CTAB,  intently pursued  by TritonX100,  while Brij 35 slacked. The inhibiting effect of Tween 80 on corrosion of steel in 1M HCL is studied by  weight loss technique. Meanwhile, the concentrations of the non-ionic surfactants utilized are in ppm (parts per million), and it is proven that nonionic surfactants which are more environment friendly compared to cationic surfactants pl ay a major role in coatings for carbon steel equipment and is alsoexceptionally cost-effective and hence can be a worthy substitute to CTAB which is a cationic surfactant. And, cationic surfactants are very expensive than nonionic because of the high-pressure hydrogenation reaction carried out during their synthesis hence a better substitute for corrosion inhibition is nonionic surfactant.