SYNERGISTIC EFFECT OF NEPHELIUM LAPPACEUM (RAMBUTAN) RIND EXTRACT AND HALIDE SALTS AS CORROSION INHIBITOR FOR CARBON STEEL IN ACID SOLUTIONS

• Main Author: Adiputra Tamba, Yansen
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67736
• Institution: Institut Teknologi Bandung

Corrosion is a spontaneous destructive process that occurs in metals and metal alloys caused by chemical, biochemical reactions, and electrochemical interactions between metals and alloys with the environment. Corrosion can occur in industries, infrastructures, and other sectors such as energy, transportation, chemical, food and beverage, oil and gas, pharmaceuticals, machinery, and civil engineering. Corrosion process can be controlled by applying basic knowledge of corrosion principles such as the addition of corrosion inhibitors to acidic environments. One of the environmentally friendly corrosion inhibitors (green inhibitors) is plant extracts. This study used Nephelium lappaceum or commonly known as 'rambutan' rind extract and the addition of halide salts to increase the efficiency of inhibitors. This study was conducted to determine the synergistic effect of rambutan rind extract and halide salt as corrosion inhibitors for carbon steel in acid solutions using weight loss test and electrochemical tests. A series of experiments were conducted to determine the synergistic effect of halide ions and rambutan rind extract inhibitors that occur in ASTM A36 steel. The experiment began with a 24 hours immersion test in blanks (HCl 1 M and H2SO4 0.5 M), a mixture of blank solutions and inhibitors with a concentration of 6 gpl dissolved HCl 1 M and 5 gpl dissolved H2SO4 0.5 M, and a mixture of blank solutions and inhibitors with the addition of halide ions from salts KCl, KBr, and KI with a salt concentration of 0.001 M respectively. Then electrochemical tests were carried out in the blank solution and a mixture of blank solution and inhibitor with the addition of halide ions from KI salts with variations in concentrations of 0.001 M, 0.003 M, 0.005 M, and 0.01 M. The results of immersion tests and electrochemical tests were then proceed to obtain corrosion rate, inhibition efficiency, halide ion synergistic parameters, and equivalent electrical circuits on carbon steel. The immersion test study results showed that adding halide ion concentrations to inhibitors lowered the corrosion rate and increased the inhibition efficiency. The lowest corrosion rate and the highest efficiency at 24 hours immersion at room temperature in HCl 1 M was 0.4118 mm/year and efficiency was 97.35% with KI salt concentration of 0.01 M and in H2SO4 0.5 M is 0.7051 mm/year and efficiency was 97.79% with KI salt concentration of 0.01 M. The electrochemical tests showed that the lowest corrosion rate and the highest efficiency in HCl 1 M was 3.425 mm/year and efficiency was 96.28% with KI salt concentration of 0.01 M and in H2SO4 0.5 M was 0.884 mm/ year and efficiency was 99.23% with a salt concentration of KI 0.01 M.