Cellulose dissolution and regeneration using various imidazolium based protic ionic liquids

A new series of six protic ionic liquids (PILs) comprising substituted imidazolium cations paired with lactate or glycolate anions were synthesized for cellulose dissolution. All the six synthesized PILs were able to dissolve about 5 wt% of cellulose. Especially, 1-ethyl imidazolium lactate showed highest dissolution power since 5 wt% of cellulose solution was obtained within 20 min at 80 °C. The effects of dissolution temperature on cellulose dissolution time were also investigated. As the dissolution temperature increases, dissolution time reduces significantly. The regeneration of cellulose with higher yield was achieved by adding anti-solvent like deionized water to the cellulose solution. Both the initial and regenerated cellulose samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) analysis. The results showed that the crystalline structure of initial cellulose (cellulose I) gets converted to cellulose II. In addition, all regenerated cellulose possessed nanostructure and lower thermal decomposition temperature than the initial cellulose and had new vistas in the industrial applications.