Comprehensive study of lumped kinetic models and bio-oil characterization in microwave-assisted pyrolysis of Sargassum sp.

Indonesia, renowned for its tropical marine environments, boasts a rich diversity of macroalgae, with Sargassum being a major contributor. Currently, the primary application of Sargassum revolves around alginate extraction, prompting a systematic exploration of alternative end-products for optimal utilization. Thermochemical conversion of Sargassum into bio-oil, biochar, and gas, particularly through microwave-assisted pyrolysis (MAP), emerges as a promising avenue. MAP, distinguished by its energy-efficient process and high heating rate, stands as a viable alternative to conventional pyrolysis. A thorough feasibility analysis of MAP, incorporating kinetic studies and bio-oil characterization, revealed that particle sizes of 40-70 mesh exhibited the highest reaction rates. Sensitivity tests validated the reliability of kinetic parameters (A and Ea) obtained from MATLAB 2016b, confirming their suitability for scaling-up purposes. These findings underscore the potential of MAP compared to conventional pyrolysis, driven by its rapid heating rates. The resulting bio-oil, with a pH of 8, comprised carboxylic acids and aliphatic, cyclic aliphatic, and aromatic compounds, along with sterols and polyaromatic derivatives that can be further utilized particularly as building blocks and end-products in chemical industries. However, it is crucial to note that the bio-oil poses challenges in the upgrading process to transform it into fuel. © 2024 The Royal Society of Chemistry.