Improving the Efficiency of Biomass Pretreatment and Enzymatic Saccharification Process by Metal Chlorides

A series of metal chlorides with different valences were used during biomass pretreatment and enzymatic saccharification. After pretreatment, the solid substrate (SS), pretreatment liquor (PL), and conversion yield of cellulose (CYC) were characterized. The results showed that the monovalent salts, NaCl and KCl, as well as the divalent salts, MgCl2 and FeCl2, could promote the enzymatic saccharification to a certain extent, while CaCl2 had little influence on the enzymatic saccharification and cellulase activity, and ZnCl2 had an inhibitor effect on them. For a trivalent salt, FeCl3, the removal rate of hemicellulose and the CYC could come up to a high value. The hemicellulose degradation was mainly related to the valences of metal ions. The cellulose models, the enzymatic saccharification, and the enzyme activity assay results showed that most of the metal chlorides had promoter action toward the enzymatic hydrolysis and cellulase activity, with the exception of ZnCl2. Moreover, the metal ions, especially with high valences, had local effects, which could intensify the potentiation or inhibition impacts on the cellulase activities.