Tannins of Deciduous Trees Bark As a Potential Source for Obtaining Ecologically Safe Wood Adhesives

Abstract

The bark of deciduous trees grown in Latvia: grey alder, black alder, ash tree and goat willow were sequentially extracted using solvents of increasing polarity. The data about total content of both lipophilic and hydrophilic compounds were obtained using sequentially extraction with hexane and ethanol. The highest yields of hydrophilic extractives were found for grey alder and ash tree barks (25.7% and 25.8%, respectively). Hydrophilic extract from the both alder species contained high amount (up to 12% on bark dry mass) of condensed tannins (CT) or oligomeric proanthocyanidins, whereas CT content of extract from ach tree was negligible. The main component of ethanol-water extract from alder bark was identified using 13 C NMR and MALDI-TOF MS spectroscopy as a mixture of A-and B-type oligomeric procyanidins with the epicatechin units polymerization degree of 2-7. Ecologically friendly wood adhesives were obtained on the condensed tannin basis.

Bark Characterisation of the Brazilian Hardwood Goupia glabra in Terms of Its Valorisation

“…The tannin content of G. glabra bark (24.2 mg CE/g extract, 3.6 mg CE/g of bark) was low when compared with barks of other species: The values for the ethanol-water extract of Alnus incana and Alnus glutinosa barks were in the range of 434 and 343 mg/g of extract, respectively (Janceva et al 2011) and 55 mg CE/g extract for C. langsdorffii bark (Carmo et al 2016). The acetone-water extract of bark of the E. globulus stump contained 29 mg GAE/g extract (Luis et al 2014) and E. tereticornis bark 103 mg tannic acid equivalents/g of bark (Puttaswamy et al 2014).…”

Bark anatomy, chemical composition and ethanol-water extract composition of Anadenanthera peregrina and Anadenanthera colubrina

“…Tannins in the barks of Alnus incana and A . glutinosa represent respectively 43% and 34% of the extract [ 53 ].…”

Tannin-based biosorbents for environmental applications – A review

“…Quebracho heartwood [19,20] 20-30 Wattle (acacia bark) [19] 15-50 Black oak [19] 8-12 Pinus pinaster bark [20] 22.5 Eucalyptus bark [21,22] 16-40 Mangrove bark [19] 15-42 Chestnut (endodermics/hull) [23] 2.50/0.94 Chestnut wood [19] 4-15 Grey and black Alder [24] 12…”