A COMPUTATIONAL STUDY OF METHANOGENESIS REACTION FROM PALM OIL MILL EFFLUENT (POME) DECOMPOSITION TO BIOGASES WITH CHEMISTRY, LIFE, UNIVERSE, AND EVERYTHING (CLUE) APPROACHES

• Main Author: Azlina Oktavianti, Nur
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/75188
• Institution: Institut Teknologi Bandung

Palm Oil Mill Effluent (POME), the most considerable waste generated from palm oil processing plants, can be used as teaching material for high school Chemistry. This liquid waste contains a significant amount of methane gas (CH4), which can contribute to environmental pollution. However, CH4 gas can also be harnessed as a renewable energy source, known as biogas. Converting POME waste into biogas occurs through four stages of reactions: hydrolysis, acetogenesis, acidogenesis, and methanogenesis. Methanogenesis is the decomposition reaction of acetate to form CH4 gas with the assistance of methanogenic bacteria under anaerobic conditions. Methanogenesis can proceed through two pathways: concerted and stepwise. Both reaction pathways are studied for their mechanisms and energetics using computational studies employing Density Functional Theory (DFT). DFT calculations use the B3LYP functional theory and the def2-SVP basis set. These functional theories and basis sets are used for optimizing compound species and searching for transition states. Based on the calculation results, the concerted reaction exhibits an activation energy of 435.12 kJ/mol; meanwhile, the stepwise reaction has three activation energies of 228.56 kJ/mol, 281.31 kJ/mol, and -17.52 kJ/mol, respectively. Among these activation energies, the rate-determining step in the stepwise reaction is the second transition state (TS-2) due to its highest activation energy, making this particular step the slowest in the reaction. Considering the energies and reaction pathways, the stepwise reaction is preferred due to its lower activation energy in the rate-determining step than the concerted reaction's activation energy. Computational studies on the energetics of methanogenesis reveal that this reaction has ?H = -68.67 kJ/mol, ?G = -61.87 kJ/mol, and ?S = -6.80 kJ/mol. The computational studies, particularly the stepwise reaction in Stages 1 and 2, are developed into teaching chemistry materials for high school. The relevance between computational studies and Chemistry topics is analyzed using the Chemistry, Life, Universe, and Everything (CLUE) approach. The CLUE approach discusses the interconnections between topics in the subject of Chemistry. CLUE divides the field of Chemistry into four core topics: Structure and Properties (SP), Bonding and Interaction (BI), Change and Stability (CS), and Energy (E). The content presented in the teaching materials is aligned with the Merdeka Curriculum and linked to the CLUE analysis. Overall, the teaching materials focus on the Strengthening the Profile of Pancasila Students (P5) theme, as the Merdeka Curriculum advocates. One of the P5 themes used for developing teaching materials is Sustainable Lifestyle. The expanded computational studies and the P5 theme are used to study the topic of New and Renewable Energy as reinforcement for the Energy Phase (E phase) in Grade X. Additionally, the topics of Formula and Molecular Structure (CLUE: SP and BI), Reaction Rate (CS), and Thermochemistry (E) are studied for the F phase in Grade XI. The application used to develop the teaching materials is Google sites, which is web-based, user- friendly, and easily accessible from anywhere. The feasibility test conducted with teacher and student respondents indicates that the developed Google site is highly suitable as a learning media, with an average percentage response rate of 93.07% from teachers and 80.27% from students. The pretest-posttest results from the students also show improved knowledge about methanogenesis reaction, with scores increasing from 50.88 to 97.06.