The Effect of Biodiesel Concentration on Microbial Metabolism Activities and Carbon Steel Biocorrosion

• Main Author: Steven
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/38791
• Institution: Institut Teknologi Bandung

Corrosion caused by micoorganism (microbially influenced corrosion or MIC) is a type of corrosion which involve microorganism in its process and can be caused by several external factors. One of external factors which play an important role in the process of MIC is metabolite concentration produced by microorganism. MIC in biodiesel storage tank is caused by biodiesel’s hygroscopy. Previous research shows that dominant microorganisms found in biodiesel transporting pipeline are Bacillus sp. and S.marcescens also metabolite products of those microorganisms are known to contain carboxyl functional group. Previous research postulate that metabolites produced do contribute to corrosion process in biodiesel storage tank. Therefore, this research aim to relate the effect of biodiesel concentration towards microbial metabolism activities on carbon steel biocorrosion. After being able to relate them, hopefully, corrosion will not longer be an obstacle in industrial scale biodiesel production. In order to achieve our target, this research is conducted by soaking carbon steel metal pieces in test solution. Test solution is a mixture of diesel oil and biodiesel with composition of 15% biodiesel, 20% biodiesel, 30% biodiesel which have been adjusted to ESDM’s law. Soaking process takes 20 days in room temperature and pressure. While soaking, several analysis such as TPC (total plate count), SEM (scanning electron microscopy), gravimetry, titration dan GC (gas chromatography) – MS (mass spectrophotometry) are done. Based on the experiment, the higher concentration of biodiesel in diesel oil, the growth and rate of corrosion is increased. The presence of B. megaterium in diesel-biodiesel oil has higher corrosion rate than S. marcescens. Corrosion products formed by both microorganisms are Fe2O3 and Fe3O4 while they also formed pitting corrosion. Metabolites of both microorganisms which is acid do not significantly increase corrosion rate but inhibit microorganism growth.