Bioconvertion of PKO to Rhamnolipid by Mutant Pseudomonas stutzeri BK-AB12 MT-03 and Its Aplication as Environmentally Friendly Corrosion Inhibitor Agents
Rikzan Zuhdi, Rukman Hertadi

Institut Teknologi Bandung

Abstract

Steel is primary material used for infrastructure because it is hard and highly resistant. However, steel can corrode when it comes into contact with the environment. Giving synthetic corrosion inhibitors as the main solution to prevent corrosion can be toxic, making things worse. For this reason, this study aims to examine the inhibitory potential of rhamnolipid bioconverted from Palm Kernel Oil (PKO) by mutant Pseudomonas stutzeri BK-AB12 MT-03 on steel material. In the early stages, the composition of PKO as the main substrate was tested using GC-MS. Then, the production and extraction of rhamnolipids were carried out using Pseudomonas stutzeri BK-AB12 MT-03. Then, characterization of the FTIR functional groups, physicochemical tests, and rhamnolipid stability were carried out by determining the decrease in surface tension of water and testing the potential for corrosion inhibitors using the weight loss method. The results show that the main constituents of PKO are natural lauric acid, myristic acid, and 9,10-dihydroxy decanoic acid. PKO was successfully converted into rhamnolipid as a brownish paste with a gain of 464.0 +- 37.8 mg/L of the medium. Analysis using FTIR showed the presence of aliphatic O-H, C-H vibrations, unsaturated C-H, and C=O groups which is typical for rhamnolipid vibrations. The CMC value of the rhamnolipid sample was found to be 52.8 mg/L with a decrease in surface tension of up to 27.80 mN/m. The surface activity of rhamnolipids is known to be stable against increasing salt concentration, temperature, and pH, indicating the potency of rhamnolipids under various environmental conditions. The percent inhibition efficiency (%EI) of rhamnolipids showed a maximum value of 59.75% at a concentration of 300 ppm. The attachment of rhamnolipids to the steel surface follows the Langmuir isotherm which indicates monolayer adhesion. The results showed that rhamnolipid can be used as a corrosion inhibitor for steel materials.

Keywords: corrosion inhibitor, eco-friendly, PKO, Pseudomonas stutzeri BK-AB12 MT-03, rhamnolipids.

Topic: Biokimia Lingkungan