Acid-Catalyzed Atmospheric Organosolv Treatment By Using gamma-Valerolactone and Ethylene Glycol For The Delignification of Hazelnut Shell and Precipitation of Lignin

Abstract

Lignin-based biorefineries are gaining importance day by day to obtain many value-added products from lignin. One of the most important processes that allow the recovery of both cellulose and lignin in those biorefineries is organosolv pretreatment. In this study, organosolv pretreatment was applied to the hazelnut shell at 130 °C for 60 min with ethylene glycol and γ-valerolactone solvents in the presence of a catalyst (either phosphoric acid or acetic acid). The success of solvent-catalyst systems was assessed by delignification efficiency and lignin recovery. Lignins obtained by precipitation were also analyzed by FTIR, TGA, DSC and Py-GC/MS. Highest delignification efficiency (33.9%) was detected for ethylene glycol- phosphoric acid solvent-catalyst pair. It was observed that acetic acid was not an effective catalyst compared to phosphoric acid. The delignification efficiency of γ-valerolactone was low (< 26 %) under atmospheric conditions, and in the presence of acetic acid, lignin was not precipitated from GVL system.

Keywords

• organosolv treatment
• delignification
• ethylene glycol
• gamma-valerolactone
• lignin recovery