In situ quantitation of ring-conjugated ethylenic lignin-units in spruce thermomechanical pulps by FT-Raman spectroscopy

Abstract

With the objective of using FT-Raman to quantitatively analyze ethylenic units in lignin in thermomechanical pulps (TMPs), coniferyl alcohol, coniferin, coniferaldehyde, and G-DHP lignin models were used to first demonstrate that the technique was fully capable of quantifying ring conjugated ethylenic units. Based on this result, the amount of ethylenic units in TMP was determined by quantifying the unit-specific contribution to the Raman spectra. The findings were that, in fully bleached spruce TMP (brightness 79.9%), the concentration of coniferyl alcohol ethylenic units was 1.38% and in the case of unbleached TMP, the amount of coniferaldehyde ethylenic units was 1.1%. Another interesting observation was that, compared to spruce wood, the amount of coniferaldehyde ethylenic units was almost 100% higher in unbleached TMP.

Citation

Agarwal, Umesh; Ralph, Sally A. 2003. In situ quantitation of ring-conjugated ethylenic lignin-units in spruce thermomechanical pulps by FT-Raman spectroscopy. 12th ISWPC International Symposium on Wood and Pulping Chemistry : Madison, Wisconsin, June 9-12, 2003, proceedings. Volume III, Poster presentations. [Madison, WI : University of Wisconsin--Madison, Dept. of Forest Ecology and Management, 2003]: Pages 119-122