Separation and recovery of lignin from hydrolysates of lignocellulose with a polymeric adsorbent

Separation and recovery of lignin from monosaccharide rich hydrolysates of lignocellulose by adsorption was investigated. Six polymeric adsorbents were compared by batch equilibrium experiments. XAD-16N was found to be the most efficient. Use of XAD-16N was studied in more detail in a column. A good separation efficiency could be obtained: with 95% monosaccharide recovery yield limit, the lignin removal level was 80%. Organic acids and furans were not adsorbed on XAD-16N. Practically all of the adsorbed lignin could be recovered efficiently with 50 wt.% aqueous ethanol solution. The lignin fraction had 99% purity with respect the other solutes in the hydrolysates. Applicability of the process on large scale was demonstrated successfully by scaling up the process using data obtained with a laboratory scale unit (scale-up factor: 420). A 76% lignin removal (target: 70%) was achieved with higher than 95% monosaccharide recovery yield (target: 95%).