The microwave irradiation (mi) process to extract acetic acid lignin from straw had been studied.

Acetic acid lignin (al) from acetic acid pulping was isolated and purified. Chemical structure and molecular weight of al were studied with infrared spectroscopy and GPC determination.

The water insoluble precipitate (acetic acid lignin, AcL) had a low weight-average molecular weight range from 341 to 253 (Mw) and a narrow molecular weight distribution from 1.1 to 1.2.