Improvement of agave bagasse hydrolysates processing under a biorefinery approach

Abstract

SummaryThe economic viability of producing second-generation bioethanol from agave bagasse (AB) is influenced by the presence of phenolic compounds in the hydrolysates used during fermentation. These compounds substantially constrain the growth in yeasts that convert sugars into bioethanol, thus becoming a limitation for the process. In this study, we proposed selecting an effective adsorbent matrix to remove and recover phenolic compounds from AB hydrolysates. We described and characterized the related adsorption phenomena and processes. Four adsorbents were examined, including activated carbon (AC), as well as three polymeric matrices (MN-102, ADS-800EP, and SP825L). The adsorption parameters, such as maximum equilibrium adsorption capacity (qmax) and percent desorption, were determined through adsorption–desorption experiments in batch systems. Additionally, we assessed the impact of removing phenolic compounds on bioethanol yield and explored the potential use of the recovered phenols as biopesticides against plant pathogens, such as fungi and nematodes. The results showed that activated carbon has a higher phenol adsorption capacity (qmax = 118.1 mg/g) but a lower desorption capacity (59.46 %), meanwhile, the MN-102 matrix displayed comparable adsorption characteristics and superior desorption capacity (95.81 %), rendering it the most appropriate for the process. Subsequently, the detoxification of the phenolic compound's impact on bioethanol yield was assessed and resulted in a significant increase, amounting to a 3.5-fold surge in bioethanol yield. Finally, the biopesticidal potential of the recovered phenolic compounds was evaluated on Fusarium oxysporum and Alternaria alternata, while the nematocidal activity was evaluated on Meloidogyne incognita juveniles. The phenolic compounds exhibited high antifungal activity against F. oxysporum (73.91 %) and moderate activity against A. alternata (40 %), in comparison to the positive control. Moreover, they showed very high nematicidal activity, causing 91.23 % mortality in M. incognita. These findings conclude that incorporating the adsorption stage not only enhances bioethanol yields but also enables the efficient recovery of compounds with high-added value.