Abstract
Through the phase-separation system, lignocellulosics were converted and separated to lignin-based polymers (lignophenols) and hydrolyzed carbohydrates. The resulting lignophenols had unique functions such as highly phenolic characteristics, very light colors and high stabilities which conventional lignins did not have. The phase-separation system composed of phenol derivatives and a concentrated acid was brought to act by a simple stirring operation for about 60 minutes at ambient temperature in an open container. To enhance the efficiency of the phase-separation reaction, the system interface between the phenolic and aqueous phases was irradiated by ultrasound. The ultrasonication greatly accelerated both the hydrolysis of carbohydrates and the grafting of p-cresol to native lignin to give ligno-p-cresol in a high yield (ca. 90% of Klason lignin). The ligno-p-cresol from the treatment with ultrasonication had high molecular weight (about 30,000) and a high dispersion index, due to effectiveness in the hydrolysis of carbohydrates, compared to that derived by the control reaction.
