Cresol red as corrosion inhibitor in chitosan thin layers on zinc

Introduction Chitosan (Chit) is a biopolymer which is synthesized by the deacetylation of chitin extracted from the shells of crustaceans. In the past few years, chitosan was widely used in physical and electrochemical research due to its costefficiency, low toxicity and ecofriendly nature [1]. The corrosion inhibition potential of chitosan is due to the amino and hydroxyl groups present in the polymer structure. Chitosan can provide a possible temporary coating on several metal layers [2-3] and the anti-corrosive properties can improve by adding different inhibitors in the chitosan system. Cresol red (CR) is a widely used pH indicator, red below 1 pH, yellow/orange at pH below 7.2 and purple color at pH higher than 8.8. In the pH range between 7.2 and 8.8 is red [4]. This study focuses on the influence of cresol red as a possible corrosion inhibitor for chitosan thin layers on zinc substrates and at the same time a possible indicator of corrosion process starting by color change of the coating.