Chemometric Study on Alkaline Pre-treatments of Wood Chips Prior to Pulping

Abstract

Alkaline pre-treatments were performed for the production of organicscontaining effluents from silver/white birch (Betula pendula/pubescens) and Scots pine (Pinus sylvestris) chips prior to chemical pulping. Pretreatment conditions were varied with respect to time (from 30 min to 120 min), temperature (130 °C and 150 °C), and alkali charge (1, 2, 3, 4, 6, and 8% of NaOH on oven-dried wood). The analytical data (total content, weight average molar mass, and molar mass distribution) on dissolved lignin were subjected to principal component analysis to examine the relationship between molar mass and molar mass distributions in lignin removed from different wood species under varying alkaline pre-treatment conditions. Using this method, differences between the wood species and effects of the various pre-treatment process variables (i.e., time, temperature, and alkali charge) were determined.

Tapping the Full Potential of Infrared Spectroscopy for the Analysis of Technical Lignins

“…The limited access to isolated lignins across the entire commercial spectrum may be responsible for this evident lack in reliable statistical data, as in most cases only a rough range could be stated for parameters, but no information on the underlying distribution of structural properties among the available lignins. [18][19][20][21][22][23][24] As already emphasized, multivariate calibrations require larger sets of reference compounds -typically at least several dozens -of which a fraction is put aside as independent test set for validation. Technical lignins are not an overly widespread and versatile commercial product, therefore the authors of earlier studies followed two different strategies to increase the number of available samples: (1) all available samples, also impure ones, were used regardless of their nature; or (2) a very low number of samples was multiplied by fractionation.…”