RAMBUTAN PEEL EXTRACT AS GREEN INHIBITOR FOR MILD STEEL: ELECTROCHEMICAL TEST

• Main Author: Raditya Kei Syam, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57887
• Institution: Institut Teknologi Bandung

Corrosion is a destructive mechanism that occurs in metals due to their reaction with the environment. For example, for mild steel ASTM-A36 series which has high tendency to oxidize when used in an open environment. ASTM-A36 series is widely used in automotive, building, piping, and oil and gas industries. Therefore, a corrosion control mechanism is needed by using inhibitors. Inhibitors that being developed are green inhibitors. The main requirements for green inhibitor are cheap, environmentally friendly, and have a significant effect in reduce of corrosion rate. Green inhibitors can be taken from various sources like parts of the fruit or plant. Therefore, this research focus on rambutan peel extract as a green inhibitor on steel in hydrochloric acid solution. In this research, various concentrations of rambutan peel were conducted. Solvent extraction was used to gain rambutan peel extract using ethanol. The extract obtained will be mixed with 1 M HCl solution to make the test solution. Various solution that used was 1 M HCl (blank) and solution with 1 gpl and 2 gpl inhibitor concentration. Sample was prepared by mounting and polished using polishing paper from grid 60-2000 to be used as working electrode. The electrochemical test was carried out using three electrodes method. Steel sample as working electrode, Ag/AgCl as reference electrode, and carbon rod as auxiliary electrode. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test were carried out to obtain Nyquist and Bode curves, also polarization curves. The data obtained was then compared with data from published papers about green inhibitor extracted from fruit or plant parts tested on mild steel in HCl solution. Electrochemical test results showed that the corrosion rate decreased, meanwhile inhibitor efficiency increased with the addition of inhibitor concentration. Steel tested in solution with inhibitor concentration of 2 gpl has a corrosion rate of 0.019 mm/year with efficiency of 96.91%, better than solution with inhibitor concentration of 1 gpl that has a corrosion rate of 0.048 mm/year with efficiency of 91.19%. However, in this research the optimum concentration of inhibitor has not been obtained due to the limited data obtained and some inaccurate data. The equivalent circuit model with addition of inhibitor from rambutan peel extract can be written as Rs- (CPEi (Ri (CPEdl / Rp))). The model indicates the presence of uneven organic layer on the steel surface.