Water-soluble carboxymethylchitosan used as corrosion inhibitor for carbon steel in saline medium

Ruza Gabriela Medeiros de Araújo Macedo; Nívia do Nascimento Marques; Josealdo Tonholo; Rosangela de Carvalho Balaban

doi:10.1016/j.carbpol.2018.10.081

Water-soluble carboxymethylchitosan used as corrosion inhibitor for carbon steel in saline medium

Carbohydr Polym. 2019 Feb 1:205:371-376. doi: 10.1016/j.carbpol.2018.10.081. Epub 2018 Oct 26.

Authors

Ruza Gabriela Medeiros de Araújo Macedo¹, Nívia do Nascimento Marques¹, Josealdo Tonholo², Rosangela de Carvalho Balaban³

Affiliations

¹ Universidade Federal do Rio Grande do Norte - UFRN, Natal, RN, Brazil.
² Universidade Federal de Alagoas - UFAL, Maceió, AL, Brazil.
³ Universidade Federal do Rio Grande do Norte - UFRN, Natal, RN, Brazil. Electronic address: balaban@supercabo.com.br.

PMID: 30446117
DOI: 10.1016/j.carbpol.2018.10.081

Abstract

Biodegradability and ecotoxicity of products used in oil industry are of great relevance and corrosion inhibitor could not be an exception. In earlier reports, chitosan and some derivatives were evaluated as corrosion inhibitors at acid pH, mainly due to polymer solubility. An eco-friendly corrosion inhibitor with water solubility in all pH range should be ideal, as well as that could act under the high salinity of oil field environment. Thus, herein is presented the performance of a water-soluble carboxymethylchitosan (CMC) as corrosion inhibitor in presence of chlorides (3.5% NaCl) in 1020 carbon steel, without any addition of acid or base. CMC showed good properties as corrosion inhibitor in media containing Cl^-, and behaved as an anodic inhibitor. CMC exhibited inhibitory efficiency of about 80% and 67%, according to Tafel curve and electrochemical impedance, respectively, which was attributed to chemisorption mechanism (ΔG_ads ≈ -45 kJ/mol).

Keywords: Carbon steel; Carboxymethylchitosan; Chlorides; Corrosion inhibitor; EIS; Polarization.