Georgia Tech Researchers Transform Pulp Mills into Biorefineries

Georgia Tech researchers are pioneering a transformative approach for Georgia's $41 billion forest products industry, aiming to reimagine pulp mills as advanced biorefineries. For nearly a decade, Sankar Nair, a professor in Chemical and Biomolecular Engineering, has led a project focused on enhancing the efficiency and profitability of kraft pulp mills.

Initially focused on energy savings, the vision has expanded to utilizing the "black liquor" byproduct, traditionally processed through an energy-intensive chemical recovery loop. The team's innovation involves using membranes to dewater black liquor, which could halve energy consumption. More significantly, these membranes fractionate the black liquor into streams rich in lignin and organic acids.

From the lignin-rich fractions, the researchers have created carbon materials suitable for battery anodes and adsorbents for environmental remediation. These lignin-derived carbons offer a domestic alternative to graphite, a critical battery material currently reliant on overseas production. The organic acid streams are being converted into heavier molecules for high-performance industrial lubricants and additives.

This development is crucial for the long-term competitiveness of the forest products industry, as the new products derived from lignin and organic acids have both substantial market demand and higher potential pricing than traditional pulp outputs. Georgia Tech has published findings on this research in ACS Sustainable Chemistry & Engineering and ACS Catalysis.

A significant challenge being addressed is the scalable manufacturing of the specialized membranes. Collaborations with Georgia Tech's advanced manufacturing experts are focusing on low-cost, continuous production methods. Tequila Harris, a professor in Mechanical Engineering, is leading the charge to transition from small-scale batch production to an industry-ready, roll-to-roll system capable of producing long sheets of membranes at high speeds, utilizing vacuum pressure to avoid volatile organic solvents.