STUDY OF NEPHELIUM LAPPACEUM (RAMBUTAN) EXTRACTS AS CORROSION INHIBITOR FOR STEEL IN HCL 1 M SOLUTION: GRAVIMETRIC METHOD

• Main Author: Firmansyah Putra, Ferry
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57960
• Institution: Institut Teknologi Bandung

Corrosion causes economic losses as reported by NACE in 2016 that the global cost of corrosion was US$2.5 billion, equivalent to 3.4% of world GDP. In addition, corrosion also causes environmental impacts such as causing casualties and environmental pollution. Various methods are used to control corrosions, one of the most common method is corrosion inhibitors. Conventional corrosion inhibitors have several problems such as being relatively expensive and toxic. Currently, many studies have been carried out related to environmentally friendly inhibitors that can overcome this problem, one of which comes from plants. Organic compounds in plants such as tannins and flavonoids have the ability to inhibit corrosion. Rambutan is known to contain these compounds. This research was conducted to determine the corrosion inhibition of steel using rambutan peel extract in a 1 M HCl environment using the gravimetric method. In this study, the immersion test was carried out for two days at room temperature and six hours for temperature variations of 35?, 45?, and 55? and with inhibitor concentrations of 0, 1, 2, 3, and 4 g/l. Extraction method with ethanol solvent was carried out to obtain rambutan peel extract, then diluted with HCl 1 M solution. The results of the immersion test were then processed to obtain the corrosion rate, inhibition efficiency, adsorption isotherm model, thermodynamic parameters, and adsorption mechanism. The results showed that the increase in inhibitor concentration decreased the corrosion rate and increased the inhibition efficiency. The lowest corrosion rate and the highest efficiency at immersion for two days at room temperature were 1.001 mm/year and 89.59% obtained at a concentration of 3 g/l. Increasing the temperature increases the corrosion rate and decreases the inhibition efficiency. The decrease in inhibition efficiency with increasing temperature indicates a physisorption mechanism. The adsorption isotherm models for temperatures of 25-55? are Langmuir, Frumkin, Freundlich, and Frumkin, respectively. Gibbs energy values ranged from -15.46 to -24.86 kJ/mol indicating the physisorption mechanism and the combination of physisorption and chemisorption. The increase in activation energy along with the addition of inhibitor concentration indicates a physisorption mechanism.