Sodiumlignosulphonate (sls) as corrosion inhibitor for mild steel in sulfuric acid medium

The corrosion and inhibition behaviour of mild steel in 0.5M H2SO4 in the presence of Sodiumlignosulphonate (SLS) has been investigated. The inhibitor effect of this naturally occurring SLS on the corrosion of mild steel in 0.5M H2SO4 was studied by weight loss , potentiodynamic polarization and electrochemical impedance spectroscopic methods. The inhibition efficiency of SLS on corrosion of mild steel in 0.5M H2SO4 is very good. The result of the different techniques confirmed the adsorption of SLS on the mild steel surface as the cause for the inhibition effect. Maximum inhibition efficiency of 90.9% at 18% (v/v) of SLS suggests that the presence of SLS in solution enhances the surface coverage. Based on the experimental evidences a mechanism is proposed to explain the inhibitory action of SLS.