Content Of Phenolic Hydroxyl Groups In Lignin: Characterisation Of 23 Isolated Non-Wood Lignin With Various Acids

Direct UV and difference spectra of alkaline and neutral solutions of isolated lignins are helpful in interpreting the chemistry of these fractions of biomass. UV ionization difference method has been used to determine the amount of free phenolic hydroxyl groups in isolated non-wood lignins from soda-antraquinone pulping with various acids (HNO3, H2SO4, CH3COOH and HCl). The content of free phenolic hydroxyl groups in lignin is important because of the reactivity of these groups and the effect they have on both chemical and physical properties of the lignin molecule.