Production and valorization of acetic acid from lignocellulosic biomass pyrolysis: Influence of operational conditions and membrane separation processes

Pyrolysis of lignocellulosic biomass is a thermochemical route for transforming forest and agricultural residues into valuable products. Among these, acetic acid is particularly important given its broad industrial applications in vinyl polymers, agrochemicals, and food additives. However, effectively recovering acetic acid from the aqueous fraction (fast pyrolysis) or wood vinegar (slow pyrolysis) of pyrolytic oils remains a challenge. This review summarizes the principal factors affecting acetic acid yield during fast pyrolysis, including feedstock composition (cellulose and hemicellulose), moisture content, temperature, particle size, reactor type, and residence time. Approaches such as mild pretreatments and optimized catalytic conditions can further enhance the release of acetyl groups from hemicellulose, thus raising acetic acid production. Recent advances in separation methods emphasize membrane technologies like nanofiltration (NF) and reverse osmosis (RO). These processes provide high selectivity, energy efficiency, and a reduced environmental footprint compared to traditional techniques such as liquid-liquid extraction and vacuum evaporation. Operational parameters—such as transmembrane pressure, pH, and feed composition—influence both membrane flux and retention of acetic acid. Interactions among solutes, membrane materials, and process conditions can either facilitate or hamper selective acetic acid recovery. This review highlights the potential to integrate optimized pyrolysis parameters with robust membrane systems to achieve sustainable acetic acid production. Ongoing research focuses on improving the acid resistance of membrane materials and elucidating mass transport mechanisms for scale-up. Successful implementation of these technologies will help establish a circular bioeconomy by converting lignocellulosic residues into high-value chemicals.