Membrane separation and characterisation of lignin and its derived products obtained by a mild ethanol organosolv treatment of rice straw

• DOI: 10.1016/j.procbio.2017.11.012
• Publication Date: 2017-11-22T04:16:35Z
• Authors: Patrícia Moniz; Cláudia Serralheiro; Cristina T. Matos; Carmen G. Boeriu; Augustinus E. Fri...; Luís C. Duarte; Luísa B. Roseiro; Helena Pereira; Florbela Carvalheiro
• Keywords: Organosolv; Tricin

Abstract An organosolv process using ethanol-water was optimized in order to recover high quality lignin from rice-straw previously pre-treated by autohydrolysis at 210 °C. The results showed a selective and appreciable removal of lignin under very mild conditions and the highest delignification yield occurred at 30 °C. The lignin extracts were characterised using capillary zone electrophoresis (CZE), size exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FT-IR) and 31P-NMR, and two-dimensional heteronuclear single quantum correlation NMR spectroscopy (2D-HSQC NMR), which enabled the identification of low molecular weight lignins with a syringyl/guaiacyl ratio of about 0.74 containing phenolic compounds with potential bioactive properties. In order to separate the target compounds, membrane technology has been used and an enriched extract containing value-added phenolic compounds such as tricin, vanillin, ferulic acid and p-coumaric acid was obtained. High membrane efficiency (around 80%) was obtained for target compounds.