Application of a Dowex-50WX8 chromatographic process to the preparative-scale separation of galactose, levulinic acid, and 5-hydroxymethylfurfural in acid hydrolysate of agarose

• Three useful compounds from agarose hydrolysis were separated by chromatography.
• The adsorbent used in the proposed chromatographic process was Dowex-50WX8.
• The removal of LA and 5-HMF from agarose hydrolysate was performed.
• The simultaneous recoveries of galactose, LA, and 5-HMF were also performed.
• High purities and high yields were obtained for galactose, LA, and 5-HMF.

A chromatographic process based on Dowex-50WX8 resin was proposed for the separation of three valuable compounds from the acid hydrolysis of agarose, the main component of red algae. The three compounds from such hydrolysis include galactose, levulinic acid (LA), and 5-hydroxymethylfurfural (5-HMF). The first task was focused on the recovery of galactose from agarose hydrolysate. The results from the related chromatographic separation experiments showed that high-purity of galactose product could be obtained with high yield and high productivity by setting the column loading at 18.8 vol.%. The second task was aimed to recover all the three compounds with high purities. It was confirmed that the simultaneous recoveries of galactose, LA, and 5-HMF with high purities (>98%) and high yields (>97%) were feasible at the column loading of 9.4 vol.%, which was verified first for a model solution and then for an actual agarose-hydrolysate solution. In addition, the productivity and yield of 5-HMF were found to be much higher than those of galactose and LA.