CORROSION INHIBITION OF MILD STEEL IN PICKLING ACIDS BY ETHOXYLATED UNSATURATED FATTY ACIDS.

Five unsaturated fatty acids, namely oleic, linoleic, linolenic, oleostearic and ricinoleic were ethoxylated to produce non-ionic surface active compounds. The effect of these materials has been studied as corrosion inhibitors for mild steel in pickling acids. The additives provide adequate inhibition of steel in hydrochloric acid of different concentrations at temperatures up to 80 degree C with ricinoleic acid as the most efficient (99%). The inhibition efficiency of the compounds are slightly low in sulphuric acid and the maximum inhibition was attained by oleic and linoleic acids (55%). Polarization measurements confirm the weight loss experiments and indicate that the additives under investigation act as mixed inhibitors.