Improvement of ultrafiltration performance by oxidation treatment in the recovery of galactoglucomannan from wood autohydrolyzate

Steam explosion of Aucoumea klaineana sapwood: Membrane separation of acetylated hemicelluloses

The fractionation of the aqueous effluent of Aucoumea klaineana Pierre (Okoumé) sapwood steam explosion was examined by a sequential-dilution type membrane diafiltration. The permeate and retentate fractions were characterized by HPLC-SEC, HSQC-NMR, FTIR, UV-visible and HPAE-PAD ion chromatography. Diafiltration with 10 kDa regenerated cellulose membrane has been shown to provide efficient fractionation without fouling. O2 and/or O3 acetylated xylans with a lower proportion of O2 and/or O3 acetylated glucomannans were isolated in the retentate (≈35% w/w and 1.08 w/w% based on initial effluent solid content and on initial dry wood respectively, including 65% w/w in the range 9-22 kDa). The molecular weights of the polysaccharides were significantly higher than those obtained by ethanolic precipitation. The permeate concentrated low molecular mass oligomers (90% w/w < 2.3 kDa, 1.88 w/w% based on initial dry wood) composed of pectic sugars, highly acetylated xylans (DS ≈ 0.9) and relatively high proportion of soluble lignin (≈40% w/w) including Lignin-Carbohydrate Complexes (LCCs).

Impact of Pretreatment on Hydrothermally Carbonized Spruce

Upgrading biomass waste streams can improve economics in wood industries by adding value to the process. This work considers use of a hydrothermal carbonization (HTC) process for the residual feedstock after lignin and hemicelluloses extraction. Batch experiments were performed at 200–240 °C temperatures and three hours residence time with an 8:1 biomass to water ratio for two feedstocks: Raw spruce and spruce after lignin extraction. The proximate analysis and heating value showed similar results for both feedstocks, indicating that the thermochemical conversion is not impacted by the removal of lignin and hemicelluloses; the pretreatment processing slightly increases the heating value of the treated feedstock, but the HTC conversion process produces a consistent upgrading trend for both the treated and untreated feedstocks. The energy yield was 9.7 percentage points higher for the treated wood on average across the range temperatures due to the higher mass yield in the treated experiments. The energy densification ratio and the mass yield were strongly correlated with reaction temperature, while the energy yield was not. Lignocellulosic composition of the solid HTC product is mainly affected by HTC treatment, the effect of lignin extraction is negligible.