INFLUENCE OF BIODIESEL CONCENTRATION IN DIESEL OIL FOR CORROSION OF CARBON STEEL BY Bacillus megaterium AND Serratia marcescens

• Main Author: Metanoia Pusparizkita, Yustina
• Format: Theses
• Language: Indonesia
• Subjects: Teknik kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/33536
• Institution: Institut Teknologi Bandung

ABSTRACT INFLUENCE OF BIODIESEL CONCENTRATION IN DIESEL OIL FOR CORROSION OF CARBON STEEL BY Bacillus megaterium AND Serratia marcescens By Yustina Metanoia Pusparizkita NIM: 23015017 (Master of Chemical Engineering Programme) Biofuels such as biodiesel have started to be used as an alternative source of energy, mixed with diesel oil as the diminishing of petroleum reserves. Before being distributed these fuel is commonly stored in tanks that are generally made of carbon steel. This material is generally used because it is strong and inexpensive. However, carbon steel is easily corroded either chemically or by microorganisms. In fuel storage tanks, microorganisms can accelerate the rate of corrosion due to their ability to utilize hydrocarbons as a source of nutrients, forming biofilms and producing metabolites to become corrosive and cause damage to metal. In response to the petroleum crisis, the Indonesian government issued a policy to increase the utilization of biodiesel by 30% v / v in 2025. However, the hygroscopic nature of biodiesel makes it more susceptible to contamination of microorganisms. The commonly type of microorganism includes SRB. However, recent studies have shown that other types of bacteria may also be involved. The presence of such microorganisms may contribute to corrosion of the tank. Therefore, this reseach was aimed to examine the effect of biodiesel percentage in diesel oil on corrosion of carbon steel by Bacillus megaterium and Serratia marcescens that dominate biocorrosion on hydrocarbon products. Before being used, both bacteria were cultured in Bushnell Haas and diesel medium to enter the stationary phase. Furthermore, the bacteria were inoculated into a fuel medium with 15%, 20% and 30% v/v biodiesel and then the carbon steel was soaked in the batch reactor with 800 mL of working volume for ten days. Samples were taken at regular intervals and then analyzed for the number of microorganisms, morphology and composition of the biofilm, the rate of corrosion and corrosion products. From this research it can be concluded that the higher concentration of biodiesel in diesel oil, the growth of bacteria in the biofilm and the rate of corrosion can be increased. The presence of B. megaterium can accelerate corrosion rate up to 10 times. While the presence of S. marcescens, corrosion rate can be accelerated up to 8 times compared to electrochemical corrosion rate. Variations of biodiesel concentration did not give significant affect for the biofilm composition and the v corrosion products. The biofilm composition formed group containing alcohol (O-H), fatty acids (C-H), proteins (N-H), amides (C-N), carbonyl and carboxylates. While corrosion products formed by B. megaterium and S. marcescens were Fe2O3 and Fe3O4. Accordingly both of the bacteria formed pitting corrosion. Key words: bio-corrosion, biofilm, hydrocarbons, biofuels, Bacillus, Serratia