Avaliação da histinina e da cisteína como inibidores de corrosão em sistema de aço carbono utilizado na indústria de óleo e gás

Abstract

Corrosion is the electrochemical process by which metals degrade due to reactions with their surrounding environment, resulting in a loss of mechanical and structural properties. Corrosion represents one of the major challenges faced by the oil and gas industry, leading to significant economic losses. Various compounds are used to prevent, control, or even halt corrosion in different metal alloys affected by this natural phenomenon. Different industries, such as the petroleum sector, use chemical compounds known as corrosion inhibitors. However, certain substances, while possessing inhibitory properties, may pose risks to the environment and human health. In this context, natural, non-aggressive, and ecologically sustainable compounds, such as amino acids, aqueous extracts, and ionic liquids, have been explored as alternatives to traditional corrosion inhibitors. Amino acids, in particular, have demonstrated high inhibition efficiency for a variety of materials, such as carbon steel and stainless steel, in diverse corrosive environments. This study proposes an analysis of two amino acids—histidine and cysteine—as potential corrosion inhibitors. These amino acids were investigated at concentrations of 250, 500, and 1000 ppm, as well as under temperature conditions ranging from 25, 40, and 60 °C. Additionally, the influence of a CO₂-saturated medium on the performance of the amino acids at 25 °C was investigated. To assess the efficacy of these compounds as corrosion inhibitors, gravimetric and electrochemical techniques were employed, such as potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). For surface analysis, images were collected using scanning electron microscopy (SEM) and atomic force microscopy (AFM). In the conducted tests, histidine and cysteine showed efficiencies of 91 % and 90 %, respectively, highlighting them as the most promising results. The amino acids exhibited the best inhibition response at a temperature of 25°C in a 3.5% wt NaCl medium.