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<p>This study investigates the valorization of residual microalgal biomass into functional biochar for lipase immobilization and enzymatic biodiesel production. Microalgal residue remaining after pigment and lipid extraction underwent pyrolysis at different temperatures and treatment strategies, and the most suitable support was obtained by pyrolysis at 500&#xa0;°C followed by nitric acid modification and silanization. These treatments enhanced biochar physicochemical properties, providing superior textural and chemical characteristics, including higher surface area and enhanced enzyme affinity. <i>Burkholderia cepacia lipase</i> (BCL) was immobilized on biochar by covalent bonding and physical adsorption. Among the evaluated conditions, covalent immobilization on chemically modified biochar resulted in the highest catalytic activity (4052.11 U g<sup>− 1</sup>) and immobilization yield (78%), demonstrating the positive effect of support functionalization on enzyme-support interactions. The biocatalysts were characterized by kinetic and thermal analyses, scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and Fourier transform infrared spectroscopy (FTIR). These techniques confirmed the biochar porous morphology, successful enzyme attachment, and functional groups favorable for immobilization. Kinetic analysis revealed increased substrate affinity for the covalently immobilized enzyme, while thermal stability tests showed that both immobilization strategies preserved approximately 85% of enzymatic activity after 240&#xa0;min at 45&#xa0;°C. The biocatalysts were then applied to biodiesel synthesis from babassu oil. BCL immobilized by covalent bonding on chemically modified biochar achieved complete conversion into ethyl esters and produced biodiesel with viscosity within fuel-standard limits. Reusability assays showed that the immobilized derivative retained more than 60% conversion after four consecutive cycles, corresponding to an operational half-life of 301&#xa0;h. Overall, microalgal biochar proved to be a robust, renewable, and effective support for enzyme immobilization, contributing to sustainable biodiesel production and residue valorization.</p>

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Microalgae-derived biochar from residual biomass as a sustainable support for lipase immobilization and enzymatic biodiesel production

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月17日

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  • Vitor Bertolassi Hidalgo,
  • Janaina Martins Theodoro,
  • Mariana Henriques Jacobsen,
  • Liana Alvares Rodrigues,
  • Patrícia Caroline Molgero Da Rós

摘要

This study investigates the valorization of residual microalgal biomass into functional biochar for lipase immobilization and enzymatic biodiesel production. Microalgal residue remaining after pigment and lipid extraction underwent pyrolysis at different temperatures and treatment strategies, and the most suitable support was obtained by pyrolysis at 500 °C followed by nitric acid modification and silanization. These treatments enhanced biochar physicochemical properties, providing superior textural and chemical characteristics, including higher surface area and enhanced enzyme affinity. Burkholderia cepacia lipase (BCL) was immobilized on biochar by covalent bonding and physical adsorption. Among the evaluated conditions, covalent immobilization on chemically modified biochar resulted in the highest catalytic activity (4052.11 U g− 1) and immobilization yield (78%), demonstrating the positive effect of support functionalization on enzyme-support interactions. The biocatalysts were characterized by kinetic and thermal analyses, scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and Fourier transform infrared spectroscopy (FTIR). These techniques confirmed the biochar porous morphology, successful enzyme attachment, and functional groups favorable for immobilization. Kinetic analysis revealed increased substrate affinity for the covalently immobilized enzyme, while thermal stability tests showed that both immobilization strategies preserved approximately 85% of enzymatic activity after 240 min at 45 °C. The biocatalysts were then applied to biodiesel synthesis from babassu oil. BCL immobilized by covalent bonding on chemically modified biochar achieved complete conversion into ethyl esters and produced biodiesel with viscosity within fuel-standard limits. Reusability assays showed that the immobilized derivative retained more than 60% conversion after four consecutive cycles, corresponding to an operational half-life of 301 h. Overall, microalgal biochar proved to be a robust, renewable, and effective support for enzyme immobilization, contributing to sustainable biodiesel production and residue valorization.