The Effectiveness of Fish Scale Waste-Synthesized Chitosan and Food-Grade Chitosan as Corrosion Inhibitor

Organic chitosan synthesized from fish scales and food-grade chitosan were investigated, via the potentiodynamic polarization method, as potential corrosion inhibitors on ASTM A36 iron in 3.5% NaCl solution. The results of the study revealed that chitosan, both food-grade and that synthesized from fish scales, inhibited the corrosion of ASTM A36 iron in 3.5% NaCl solution. The source of the chitosan did not have any effects on the chitosan’s behavior or potential. The inhibitor efficiency value increased as the chitosan concentration increased. The optimum concentration of the two types of chitosan was 3000 ppm; the inhibitor efficiency value decreased when the inhibitor concentration was increased to4000 ppm. This inhibitor efficiency value change occurred because at 4000 ppm, the inhibitor concentration exceeded the best conditions to form a protective layer on the surface of ASTM A36 iron. Chitosan is cathodic, regardless of the source, and both types of chitosan were similar in terms of polarization type, adsorption, and isothermal adsorption. The isothermal adsorption interaction of chitosan (from either source) followed Temkin-type kinetics with the ASTM A36 iron and had chemisorption characteristics.