Optimization of concentrated sulfuric acid saccharification process of corn straw and evaluation of ion-exchange resin for acid/sugar separation
Fermentable sugar production is the bottleneck that restricts the economical production of fuel etha-nol from lignocellulosic biomass.The production of fermentable sugars based on concentrated sulfuric acid saccharification has the advantages of high sugar recovery efficiency and no cellulase input;In this study,the optimization conditions for the production of fermentable sugars from corn straw by concentrated sulfuric acid saccharification process were explored,and the potential of commercially available resins for acid/sugar sepa-ration was evaluated.For concentrated sulfuric acid saccharification,the effects of key operating parameters such as acid/feedstock ratio(A/F ratio),hydrolysis temperature and straw moisture content on saccharifica-tion efficiency were investigated by using a two-step solubilization and hydrolysis process,and the optimized conditions(A/F ratio 1.25,hydrolysis temperature 80 ℃,moisture content 5%～10%)were achieved,in which the total sugar concentration reached 180.4～183.16 g/L,and the sugar recovery efficiency reached 79.06%～81.83%;acetic acid and colored substances were the main by-products formed during the sacchari-fication process,and the common fermentation inhibitors furfural and 5-HMF were below the critical concen-tration of fermentation inhibition.The colored substances in the saccharified liquid can be effectively removed by activated carbon adsorption and the decolored saccharified liquid was subjected to acid/sugar separation by using the commercially available strong anion exchange resin Monojet S4850 and its utilization potential was evaluated;The separation degree between sugar and sulfuric acid was about 0.59,indicating good separation capacity of sulfuric acid and sugar in the saccharified liquid.These results provide data and technical support for the development of industrial applications of concentrated sulfuric acid saccharification process to produce fermentable sugars.
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