Characterization of physically crosslinked ionic liquid-lignocellulose hydrogels

A novel hydrogel was prepared starting with a 10-wt.% lignocellulose solution that was obtained by dissolution of Norway spruce wood (Picea abies) in the ionic liquid 1-butyl-3-methylimidazolium chloride. This ionic liquid was used to avoid traditional degradative and hazardous effects of solvents on the lignocellulose. Five alternate freezing and thawing cycles of the lignocellulose solution were employed as a means of physically crosslinking the hydrogels. The obtained hydrogel network was thermoreversible, with mesopores of 5 to 35 nm diameter, predominantly amorphous, and presenting distinct behaviors when immersed in aqueous solutions with different concentrations of organic electrolytes. The specific surface area of the hydrogel was 75.23 m2×g-1.The hydrogels presented high uptake capacities for pollutant chemical species (Cu2+, Pb2+, and bemacid blue anionic dye) that spanned from 445 mg/L to 547 mg/L at a pH value of 6. This indicated that the hydrogels are promising materials for environmental applications.