Hydrophilicity and hydrophobicity consideration of organic surfactant compounds: Effect of alkyl chain length on corrosion protection

Organic compounds have been recognized as one of the utmost operative corrosion protective measures. However, their usage and synthesis are allied with the consumption and release of malignant materials. More so, out of various manufactured and settled compounds, only a few are effective. Therefore, the high mandate is to design and formulate effective compounds based on literature outcomes. Literature outcomes suggest that surfactant molecules having alkyl substituent of neither too small nor too large act as effective aqueous phase corrosion inhibitors. The present review describes the effect of alkyl/hydrocarbon chain length on the corrosion inhibition potential of some series of surfactant molecules. Generally, an increase in the alkyl chain length favors inhibition performance due to enhancing the packing of surfactant molecules at the interface of metal and electrolyte, but a very high level of hydrophobicity disfavors the inhibition performance. Hydrophilicity and hydrophobicity can be suitably tailored by varying the number and size of the hydrocarbon chain. Organic compounds containing the hydrocarbon chain length of C₁₂-C₁₆ exhibit the best inhibition efficiency (%IE). The molecules become effective by adsorbing on the metal surface. They behave as mixed- and interface-type corrosion inhibitors.