#TITLE_ALTERNATIVE#

• Main Author: SONNIA AGUSTINA (NIM:10512049), RUTH
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30734
• Institution: Institut Teknologi Bandung

<p align="justify">Biosurfactants are surface active substances produced by microorganisms as secondary metabolites under conditions of limited nutrient but rich source of carbon in the form of lipids. Recently, biosurfactants are widely used as an alternative to synthetic surfactants that are mostly not environmentally friendly. One interesting application of biosurfactant is as a corrosion inhibitor. In the present study, Halomonas meridiana BK-AB4 known as potential producer of biosurfactant in the previous study, was explored its produced biosurfactants as a corrosion inhibitor. For this study, biosurfactants were produced by growing the bacteria in the medium that has been optimized previously containing olive oil and urea as a carbon and nitrogen sources, respectively. The physicochemical characterizations of biosurfactants were reevaluated to ensure the consistency of biosurfactants activity in a variety of conditions that have been studied previously. The measured physicochemical properties of the biosurfactants exhibited high similarities with the previous studies, in which the highest activity was observed at pH 12 with the emulsification index was about 71.43%, stable in the pH range of 7-12 and in the salinity range of 15-22%. The measured CMC value of the biosurfactants was 353.8 mg/L. Structure characterizations using FTIR, NMR and LCMS suggested that H. meridiana BK-AB 4 produced four major biosurfactants, which were sodium octadeca-9Z,11Z,13Z-trienoate, sodium icosa-8Z,10Z,12Z,14Z,16Z,18Z-hexaenoate, sodium 13,15-dihydroxyoctadecanoate, and sodium dodecanoate with composition ratio of 47.5:33.8:7.1:11.6 (by weight), respectively. The application of biosurfactants as a corrosion inhibitor was evaluated in this study utilizing Electrochemical Impedance Spectroscopy (EIS) method at 25 oC, 35 oC, 45 oC and 55 oC. The results showed that the highest efficiency was observed at 45 °C with the value of &#916;G adsorption was &#61485;32.9 kJ / mol. The adsorption type of the biosurfactants on the surface of carbon steel is likely a semi-chemical and physical adsorption. The adsorption of biosurfactant on the surface of carbon steel apparently followed the El-Awady model on adsorption isotherm. Based on all of the above evaluation results, biosurfactant produced by Halomonas meridiana BK-AB 4 exhibited strong potential to be applied as an alternative material for the environmentally friendly corrosion inhibitor.<p align="justify">