A1 Journal article (refereed)
Willow bark proanthocyanidins with potential for water treatment : Chemical characterization and zinc/bisphenol A removal (2023)

Dou, J., Varila, T., Salminen, J.-P., Tuomikoski, S., Hietala, S., Hemmi, M., Hu, T., Lassi, U., & Vuorinen, T. (2023). Willow bark proanthocyanidins with potential for water treatment : Chemical characterization and zinc/bisphenol A removal. Separation and Purification Technology, 318, Article 123943. https://doi.org/10.1016/j.seppur.2023.123943

JYU authors or editors

Publication details

All authors or editorsDou, Jinze; Varila, Toni; Salminen, Juha-Pekka; Tuomikoski, Sari; Hietala, Sami; Hemmi, Maria; Hu, Tao; Lassi, Ulla; Vuorinen, Tapani

Journal or seriesSeparation and Purification Technology



Publication year2023

Publication date28/04/2023


Article number123943

PublisherElsevier BV

Publication countryNetherlands

Publication languageEnglish


Publication open accessOpenly available

Publication channel open accessPartially open access channel

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/89311


This study investigates the chemical structure of proanthocyanidin-rich crude extracts from willow bark and these materials were tested initially as adsorbents for artificial (waste)water treatment. The crude extracts were obtained through mild water extraction and the colorant fractions were further chromatographically fractionated to understand the chemical structure of the willow bark proanthocyanidins. The chemistry of crude extracts and purified fractions were investigated using nuclear magnetic resonance (NMR) and ultraperformance liquid chromatography−tandem mass spectrometry (UPLC-MS/MS). Both NMR (liquid and solid-state) and UPLC-MS/MS suggest that the crude extracts constitute of interflavan linked flavan-3-ols, i.e. proanthocyanidins with both procyanidin (PC)-type and prodelphinidin (PD)-type subunits, with the PC/PD ratio of approximately 2.3 - 2.5. PD-type proanthocyanidins were detected from the purified colorant fractions only with UPLC-MS/MS. Both the UPLC-MS/MS and size exclusion chromatography suggest that the crude extracts have an average oligomerization degree of roughly 5-6 flavan-3-ol units. Adsorption experiments showed that the activated foams made of crude extracts were effective in removing both zinc and Bisphenol A (BPA) with removal efficiencies of roughly 80-90% and thus these willow bark-derived proanthocyanidins are promising in water treatment. The significance of this study suggests the upgrading use of crude extracts for water treatment could significantly improve the value of willow bark.

Keywordsnaturally occurring substancesbarkwillowsproanthocyanidinswater treatmentwater purificationzincbisphenol A

Contributing organizations

Ministry reportingYes

Reporting Year2023

Preliminary JUFO rating2

Last updated on 2024-03-04 at 18:36