University of Oulu

Adedayo Bello, Ulrich Bergmann, Jouko Vepsäläinen, Tiina Leiviskä, Effects of tree harvesting time and tannin cold/hot-water extraction procedures on the performance of spruce tannin biocoagulant for water treatment, Chemical Engineering Journal, Volume 449, 2022, 137809, ISSN 1385-8947,

Effects of tree harvesting time and tannin cold/hot-water extraction procedures on the performance of spruce tannin biocoagulant for water treatment

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Author: Bello, Adedayo1; Bergmann, Ulrich2; Vepsäläinen, Jouko3;
Organizations: 1Chemical Process Engineering, University of Oulu, P.O. Box 4300, Oulu FIN-90014, Finland
2Department and Biochemistry and Biocentre, University of Oulu, Oulu FIN-90014, Finland
3School of Pharmacy, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.2 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2022-07-07


This study investigated the effect of seasonal variation (i.e. winter and summer) on tannin extracts from spruce bark as biocoagulants for water treatment applications. Tannins were extracted through three different water extraction procedures: cold-water extraction (21 °C), cold-water plus hot-water extraction (85 °C) and direct hot-water extraction (85 °C). 1H nuclear magnetic resonance spectra showed that the cold-water plus hot-water extractions possessed the highest proportion of phenols. Electrospray ionization-mass spectrometry indicated that a preliminary cold-water extraction sufficiently reduced the non-phenolic constituents (monosaccharides and sugars) from the winter bark in the cold-water plus hot-water extraction but not from the summer bark. The synthesis of tannin-based coagulants was performed through the Mannich reaction using formaldehyde and ethanolamine. Coagulants with the highest charge densities (3.379 ± 0.012 meq/g) were produced with tannin extracts obtained from the winter bark cold-water plus hot-water extractions. Water treatment experiments with the coagulants from the winter and summer bark cold-water plus hot-water extractions demonstrated that they were effective for particle settling. The study proved that the tree harvesting season and extraction procedure play a critical role in obtaining high-quality spruce tannin for the synthesization of tannin-based biocoagulants that provide better coagulative performance.

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Series: Chemical engineering journal
ISSN: 1385-8947
ISSN-E: 1873-3212
ISSN-L: 1385-8947
Volume: 449
Article number: 137809
DOI: 10.1016/j.cej.2022.137809
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
Funding: The authors wish to thank the University of Oulu graduate school and Maa- ja vesitekniikan ry. for providing the funding for this project.
Copyright information: © 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (