Lignin is one of the most abundant biopolymers on the earth. The pulping processes produce huge amounts of lignin from its lignocellulosic waste. One of the applications of lignin could be corrosion inhibitor. Initial corrosion studies on native soda lignin and Kraft lignin without any treatments have shown good inhibition on mild steel in 3.5% of sodium chloride solutions. The inhibitive efficiencies increased with the increase in concentrations. Both lignins can adsorb onto the metal surface physically and then react chemically with iron ions to form a protective film that hinders further...