Copper oxide functionalized chitosan hybrid hydrogels for highly efficient photocatalytic-reforming of biomass-based monosaccharides to lactic acid

Much attention has been focused on the photocatalytic-reforming of biomass to produce high-value chemicals due to their unique merits. In this study, we report a freezing-thawing strategy for the preparation of an alkaline CuO-chitosan hybrid hydrogel (CuO@CS-H). The synergism between CuO and alkaline chitosan hydrogel led to a highly efficient photocatalytic-reforming of xylose to lactic acid under a weak alkaline system, and the highest lactic acid yield is 81.6 %. The retained lactic acid yield was about 91.2 % after being used nine times. The reaction system is universal for the production of lactic acid from biomass-derived pentoses and hexoses, and O 2 − plays a major role in the synthesis of lactic acid. Industrial production of lactic acid via the as-proposed system was shown to be feasible according to a two-thousand-fold scale-up experiment. This work initiates a novel strategy of photocatalytic synthesis of lactic acid from biomass-based monosaccharides.