Improving process sustainability in bio-oil transforming for biofuels and platform chemicals production: Valorization of the carbon residue

Abstract

This work introduces a zero-waste approach to process biomass-derived raw bio-oil by addressing the valorization of the carbon residue that inevitably deposits, reducing the bio-oil conversion efficiency and leading to reactor-clogging issues. The study explores the feasibility of producing value-added porous material for removing pollutants from industrial wastewaters. An activated carbon with a specific surface area of 1070 m2 g−1 and a micropore volume of 0.41 mL g−1 was successfully produced through a simple thermochemical method involving pyrolysis, alkaline treatment, and carbonization. The impact that the activation method has on the nature, structure, and adsorption capacity of the material was assessed using methylene blue (MB) and hexavalent chromium (Cr-VI) as probe molecules. The activated carbon exhibited remarkable adsorption efficiency, achieving a removal ratio of 98 % for MB and 47 % for Cr-VI. Recyclability tests demonstrated a slight loss of adsorption capacity over multiple cycles. Kinetic studies, employing Surface Reaction Models and Mass Transfer Modeling, provide insights into adsorption rate-limiting steps. Chemisorption was identified as the most limiting stage, with physisorption and liquid film diffusion playing roles, particularly at short solid–liquid contact times. For longer contact times, intraparticle pore diffusion becomes the rate-controlling step due to the highly microporous nature of the activated carbon.