AbstractThe solubility of lignin from bagasse in mixed solution was investigated and explained by the solubility parameter (). To explore the lignin solubility, enzymatic hydrolysis/mild acidolysis lignin (EMAL) isolated from bagasse was used as the starting material to prepare lignin solution by ultrasonic treatment. The lignin content in solution was determined by UV-vis spectroscopy at a wavelength of 280 nm. The results showed that 240 minutes of ultrasonic treatment was needed to achieve lignin dissolution equilibrium in the 1,4-butanediol/water mixture. Maximum lignin solubility (14.6 g/L) occurred at a concentration of 80% (v/v). The δ-value of lignin (14.0 (cal/cm3)1/2) was calculated based on the atomic and functional groups present in the phenylpropane unit. The δ-values of the 1,4-butanediol/water showed a decrease from 22.31 to 11.09 (cal/cm3)1/2 as the concentration of 1,4-butanediol increased. The maximum lignin solubility predicted by the δ-value should occur at a concentration of 80% (v/v), which agreed with the experimental result.