Development and application of functionalized biochar for sustainable biodiesel production and adsorption of CO2 and organic molecules

Abstract

As part of a doctoral thesis focused on the design of functionalized biochar from industrial lignins for sustainable biodiesel production and CO2/organic-molecule adsorption, preliminary results from two complementary work lines are presented. At NANOTEC (UTN Facultad Regional Córdoba), the synthesis of biochar by KOH-assisted slow pyrolysis of Kraft lignin was optimized, evaluating activator/precursor ratios between 2.5 and 15 g of KOH per 5 g of lignin and carbonization temperatures between 450 and 600 °C. Formulations with 10 g (Solution A) and 15 g of KOH (Solution B) per 5 g of lignin, at 500 and 550 °C, showed the best performance: Solution A exhibited a higher net washing yield (50.9-58.7 %), while Solution B reached the highest BET surface areas (up to 617 m²/g) and pore volumes (up to 0.42 cm³/g). In parallel, at GPol (UTN Facultad Regional San Francisco), conductometric and potentiometric titration techniques were set up to quantify surface acid groups of Kraft lignin (Suzano) and lignosulfonate (LignoTech), yielding total acid group contents of 6.7 and 6.1 mmol/g, respectively, and two well-defined neutralization zones in the potentiometric titration of Kraft lignin. These results constitute the experimental basis for the subsequent activation, functionalization and evaluation stages of the obtained biochars.