Dissolution of cellobiose in the aqueous solutions of chloride salts: Hofmeister series consideration

The effects of chloride salts on the dissolution of cellobiose in aqueous solution were investigated using calorimetry and H-1 NMR. The dissolution of cellobiose in salt solutions is a typical entropy-driven process. The activity of ZnCl2 and LiCl hydrated ions is enhanced as the hydration number decreases with increasing temperature. Zn2+ and Li+ hydrates can interact with the oxygen atoms at the O5 and O6 positions of cellobiose and associate with the Cl- anions, leading to the breakage of cellobiose hydrogen bonds. We found that the solubility of cellobiose in aqueous solutions is on the order of ZnCl2 > LiCl > NaCl > H2O > KCl > NH4Cl, which is consistent with the Hofmeister series. For the first time, we recognized the specific ionic effects of the Hofmeister series on the dissolution of cellobiose in salt aqueous solutions. This finding is helpful for understanding the dissolving mechanism of cellulose in aqueous solvents with salts and providing fundamental knowledge for finding and designing new cellulose solvents.