Evaluation of pectin isolated from tomato peel waste as natural tin corrosion inhibitor in sodium chloride/acetic acid solution

Abstract The pectin from tomato peel waste (TPP) was employed as tin corrosion inhibitor with the aim to enhance the knowledge regarding the application of natural inhibitors, instead synthetic, and reducing the waste disposal for value-added biopolymers production. To evaluate the TPP anticorrosion activity the commercial apple pectin (CAP) was also utilised. The gravimetric tests show that the highest inhibitive impact (η) of 75.9 % (CAP) and 73.9 % (TPP) are gained at concentration of 20 g L-1. By electrochemical, potentiodynamic polarization and impedance spectroscopy measurements, the maximum η (60.05 - 65.5 %) are reached at lower concentration (4 g L-1), due to tendency of pectins to form viscous solution. The prominent decreases in current density with the shifts of potential in the cathodic direction revealed that pectins provided cathodic protection of tin surface. Similar inhibition impact of pectins, and fine agreement between applied methods confirmed their suitability against tin corrosion.