Pelagic Sargassum waste as an excellent feedstock for bioethanol production: hydrolysis optimisation and kinetics

Abstract

This study highlights the potential of marine macroalgae waste as a viable feedstock for bioethanol production. Compositional analyses have shown that this pelagic seaweed waste contains substantial carbohydrates. To further enhance the extraction of fermentable sugars from the biomass, a response surface methodology (RSM) statistical optimisation approach was applied, involving 27 experimental runs. Optimal hydrolysis conditions, determined through statistical analysis, consisted of a 0.8 M sulphuric acid concentration, a temperature of 130 °C, and a 60-min duration, resulting in a sugar yield of approximately 132 mg/g. The hydrolysis of Sargassum biomass followed a first-order reaction kinetics with an activation energy of 41.36 kJ/mol and a pre-exponential factor of 127 (molH2SO4)−1.s−1. Furthermore, the obtained hydrolysate was fermented using Saccharomyces cerevisiae NT116. This resulted in a maximum ethanol yield of 0.497 ± 1 g/g, highlighting the potential of this biomass in bioethanol production.