Gemini surfactants as corrosion inhibitors for carbon steel

Carbon steel is the backbone of many industries but it is susceptible to corrosion in different aggressive media especially mineral acids that are extensively used for many purposes in industry. Carbon steel corrosion is an unavoidable but a controllable process. One of the effective means for corrosion control is the use of inhibitors to reduce the aggressiveness of media on metallic materials. Corrosion inhibitors can be classified into organic, inorganic and mixture of inhibitors. A type of organic inhibitors is surfactants which can be readily synthesized with low cost and have high effectiveness and efficiency for inhibiting corrosion. Gemini surfactants are an intriguing class of surfactants which are recently used as corrosion inhibitors due to their more efficient surface properties with low values of both critical micelle concentration and surface energy. Over the past years, extensive research and development have led to synthesizing a variety of Gemini surfactants most of them are based on cationic ammonium salts with bromide as counter anion. No anionic or nonionic Gemini surfactants are reported as corrosion inhibitors for carbon steel, whereas the most efficient cationic ones used to mitigate its corrosion in the main industrial media HCl, H2SO4, sea water and formation water are highlighted. This review presents most of these contributions made to the literature in recent years with main emphasis on studying the effect of spacer and terminal chain. Most of these inhibitors have showed high effectiveness exceeding 90%.