Chitosan from Milkfish (Chanos chanos) Scales and Tiger Shrimp (Panaeus monodon) Shells Wastes as Corrosion Inhibitor on ASTM A36 Steel

Abstract

Chitosan is synthesized from milkfish scales (Chanos chanos) and tiger shrimp shells (Panaeus monodon) were used as corrosion inhibitors on ASTM A36 steel in a mixture solutions of sodium chloride (NaCl) 3,5% and acetic acid (CH3COOH) 3%. The waste of milkfish scales and tiger shrimp shells is extracted into chitin through deproteination and demineralization processes. Chitin is synthesized into chitosan through deacetylation process. The yield of milkfish scales chitosan was 31,81%, while the yield of tiger shrimp chitosan was 67,16%. Corrosion rate testing using the weight loss method then calculates the inhibition efficiency of each inhibitor. Soaking the test specimens was carried out for 4 weeks with measurements of weight, pH value and salinity each week. The concentrations used were 0 ppm as negative control, 60 ppm, 500 ppm and 1000 ppm for chitosan inhibitor and 1000 ppm sodium nitrite as positive control. The optimum inhibition efficiency of milkfish scales chitosan is 48,9% at a concentration of 60 ppm with a soaking time of 3 weeks. The optimum inhibition efficiency of tiger shrimp shell chitosan is 57,7% at a concentration of 500 ppm with a soaking time of 1 week. Milkfish scales chitosan has better effectiveness compared to tiger shrimp shells chitosan because the resulting inhibition efficiency remains stable at> 40% starting from 1 week to 4 weeks of soaking.