Effect of pH Control with Acetic Acid/Sodium Acetate Buffer on Hot-water Extraction of Poplar Wood

Poplar wood chips were extracted in an acetic acid/sodium acetate (SA/AA) buffer solution at 180 oC for 60 minutes, with a solid-to-liquid ratio of 1: 6, to investigate the effect of pH on the extraction performance in terms of chemical compositions of the extract. The pH was controlled by varying the concentrations of sodium acetate and acetic acid in the buffer system. Results showed that the SA/AA system could promote the dissolution of hemicellulose, obtaining more oligosaccharides and monosaccharides, and could also inhibit the excessive decomposition of monosaccharides. When extracting poplar wood chips in a SA/AA system of pH=3.7, the yield of oligosaccharides was the highest, while the contents of furfural and hydroxymethyl furfural decreased by 25% and 30%, respectively, compared to conventional water extraction systems. Moreover, the amount of lignin extracted in the S/AA process was also higher than that in a conventional hot water extraction process.