Preparation of activated carbon fibers with large specific surface area from softwood acetic acid lignin

Softwood acetic acid lignin (SAL) free from a high-molecular-mass fraction could be spun at 220degreesC by a spinning machine equipped with an extruder. Although the resulting fibers required thermostabilization, this step could be conducted with a faster heating rate than that for fibers obtained from hardwood acetic acid lignin (HAL). The thermostabilized SAL fibers were converted to activated carbon fibers (ACF) by carbonization in a stream of nitrogen at 1000degreesC, followed by steam activation at 900degreesC. At an activation time of 40 min, the SAL-ACF had a larger specific surface area than the corresponding HAL-ACF. When the activation time for SAL carbon fibers was prolonged to 80 min, the adsorption capacities of resulting ACF against iodine and methylene blue were markedly increased, as was the surface area of the ACE It was found that SAL-ACF had adsorption properties comparable to those of high-performance commercial ACE Also, it had a tensile strength equal to that of a pitch-derived ACF.