University of Oulu

Werner Marcelo Goldmann, Juha Ahola, Otto Mankinen, Anu M. Kantola, Sanna Komulainen, Ville-Veikko Telkki, Juha Tanskanen, Determination of Phenolic Hydroxyl Groups in Technical Lignins by Ionization Difference Ultraviolet Spectrophotometry (∆ε-IDUS method). Periodica Polytechnica Chemical Engineering, Online First (2017) paper 9269. DOI: 10.3311/PPch.9269

Determination of phenolic hydroxyl groups in technical lignins by ionization difference ultraviolet spectrophotometry (∆ε-IDUS method)

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Author: Goldmann, Werner Marcelo1; Ahola, Juha1; Mankinen, Otto2;
Organizations: 1Chemical Process Engineering, Faculty of Technology, University of Oulu, P.O. Box 4300, FIN-90014 University of Oulu, Finland
2NMR Research Group, Faculty of Science, University of Oulu, P.O. Box 4300, FIN-90014 University of Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.9 MB)
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Language: English
Published: Budapest University of Technology and Economics, 2017
Publish Date: 2017-02-24


The amount of hydroxyl groups, particularly phenolic, is one of the most important parameters in lignins, as it is an indicator of lignin reactivity. Ultraviolet (UV) Spectrophotometry is a simple and inexpensive method for determining phenolic hydroxyls in lignin. Ionization Difference Ultraviolet Spectrophotometry (Δε-method) relies on the analysis of solubilized lignin at neutral and alkaline conditions with a UV spectrophotometer. We added a slope analysis to the ∆ε-method and dubbed the resulting method ∆ε-IDUS (Ionization Difference UV Spectrophotometry). We assessed the reliability of ∆ε-IDUS by studying the well-known Indulin AT lignin. Additionally, ∆ε-IDUS was applied to a previously uncharacterized milox lignin. When compared to ¹³C-NMR, ∆ε-IDUS underestimated the amount of phenolic hydroxyls for Indulin AT, possibly due to neglecting second phenolic hydroxyls in some lignin units, which resist ionization because of steric hindrance. Nevertheless, the results agreed with previously reported values and confirm that ∆ε-IDUS is useful to screen lignins based on their phenolic hydroxyl group content.

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Series: Periodica polytechnica Chemical Engineering
ISSN: 0324-5853
ISSN-E: 1587-3765
ISSN-L: 0324-5853
Pages: 1 - 9
Article number: 9269
DOI: 10.3311/PPch.9269
Type of Publication: A1 Journal article – refereed
Field of Science: 215 Chemical engineering
Funding: The financial support of the Academy of Finland (grant numbers 289649 and 294027) is gratefully acknowledged.
Academy of Finland Grant Number: 289649
Detailed Information: 289649 (Academy of Finland Funding decision)
Copyright information: Creative Commons Attribution