Chitosan based new nanocomposites for corrosion protection of mild steel in aggressive chloride media

Abstract

Chitosan is one of the important natural bio-polymers. Besides its good green value, it is rarely used to protect metals in aggressive media in direct form due to rapid degradation of its molecules in acid. Hence, it is necessary to use some means to increase protection efficiency of chitosan. In present work, cobalt and tin sulfide nanoparticles are used to synthesize chitosan-cobalt and chitosan-SnS2 nanocomposites, and used for corrosion protection of mild steel (MS) in 1 M HCl at room temperature. The prepared composites are investigated by UV–visible spectroscopy, FTIR spectroscopy, HRSEM, HRTEM and EDAX techniques, which have shown successful formation of nanocomposites. Corrosion behavior of the composites have been examined by Tafel polarization curves (TPC), single sine electrochemical impedance spectroscopy (SSEIS) and surface analyzing techniques. The results have declared that chitosan-cobalt nanocomposite is more effective in corrosion inhibition of mild steel than chitosan-SnS2 nanocomposite. Alone chitosan provide only 77% inhibition to mild steel, while it increases for chitosan‑cobalt (>95%) and chitosan-SnS2 (>80%) composites. Isotherm study suggests that adsorption of chitosan/composites over MS is main reason of inhibition and can be best defined with Frumkin isotherm. Adsorption of chitosan and chitosan-nanocomposites over MS is also evident by SEM and AFM.