The Evaluation of Lignin Structure Changes of both pH4 and pH2 from Hardwood Dissolved Soda-AQ Lignin by ~(31)P-NMR

摘要

The Chinese poplar was cooked by Conversational Soda-AQ in the study. The acid precipitation (pH to 4, pH to 2)was adopted to separate lignin from pulping black liquor, different lignin samples were acquired. The spectra of lignin structure was obtained by ~(31)P-NMR. The functional groups in different lignin samples were quantitatively and qualitatively analyzed through the spectra. The variation of lignin structure in Soda-AQ cooking was obtained by analyzing the spectra. The content of total phenolic OH is 4.85mmol/g in lignin DAL LdpH4; 4.14mmol/g in lignin DAL LdpH2.