Synergistic effect of different salts on the inhibition efficiency of a cationic surfactant on steel corrosion in acid medium

Corrosion inhibition effect of cationic surfactant DTAB (Dodecyl Threemethyl Ammonium Bromide) on low carbon steel in 1M HCl was studied using weight loss and OCP (Open Circuit Potential) methods. Inhibition efficiency increases with increasing of surfactant concentration. Also synergistic effect between surfactant and different alkaline metals salts (KCl, NaCl, NaBr, NaI, LiCl, Na2SO4, and NaNO3) in 1 M HCl is investigated. The effect of different anions and different metal cations on inhibition efficiency is discussed. The inhibition efficiency increases with increasing of salts concentration and reaches the maximum value near 0.1 M. The results show that the synergistic effects of salts are in this order Na2SO4 >NaI > LiCl > NaCl > KCl > NaBr > NaNO3. This inhibitor system containing cationic surfactant and an alkaline metal salt is efficient and low-cast for steel corrosion inhibition in HCl medium, even when the concentration of DTAB is as low as 0.5 x 10(-4) M.