Extraction of polyphenolic substances from bark as natural colorants for wool dyeing

Abstract

In Europe, considerable amounts of bark are available from wood-processing industries such as forestry and timber production. Polyphenolic components can be collected by hot water extraction. The extracted compounds can then be applied as colorants in textile dyeing operations. In this study, a comparative assessment of four different tree species with regard to their colouristic potential for wool dyeing was performed. Aqueous extracts from alder, ash tree, spruce and oak bark were prepared and analysed for their total phenolic content and ultraviolet (UV) absorption at 360-370 nm. The extracts were used for metamordant dyeing by adding iron sulphate mordant (FeSO 4 9 7H 2 O). For comparison, iron salt-based dye lakes were prepared and used in dyeing experiments. For each tree species, a specific correlation between the total phenolic content of the dyebath and the colour depth in terms of K/S and CIELab coordinates was observed, both for the aqueous extracts and the dye lakes. Based on this relationship, standardisation and quality control of raw materials and dye lakes can be installed as important stages in the industrialisation of natural colorants from bark. The preparation of concentrated dye lakes permits formation of a concentrated colorant as dye product, which then can be standardised and delivered to textile dyehouses, similar to synthetic dyes. The preparation of dye lakes offers a relevant route towards achieving the commercialisation of bark extracts as natural colorants.

Biomordanting willow bark dye on cellulosic materials

“…[22][23][24] In general, different tree barks have been of great interest due to their high availability, and their use for textile dyeing purposes has been investigated. 25 This paper proposes using willow bark extract (WBE) as a natural colorant source for textile dyeing purposes.…”

“…Willow bark extractives have been previously employed as natural dyes, as tanning agents in leather processing due to their tannin content, and in pharmaceutical products because of their pain‐ and fever‐reducing capabilities . In general, different tree barks have been of great interest due to their high availability, and their use for textile dyeing purposes has been investigated . This paper proposes using willow bark extract (WBE) as a natural colorant source for textile dyeing purposes.…”

Environmentally friendly dyeing of wool yarns using of combination of bio‐mordants and natural dyes

“…The best results were obtained for alum as metal mordant. Binder et al 37 collected polyphenolic components from wood industries waste. These extractions were used for dyeing of wool fibers.…”

Extraction of natural dyes from the stem of Caulis spatholobi and their application on wool

“…Compared with natural dyes, synthetic dyes can produce a variety of bright shades, with fairly good color fastness, dyeing reproducibility and low cost. 1–5 However, some synthetic dyes contain heavy metals and azo groups, which are harmful to the environment and human health. 6–8 Also, the dyeing and printing wastewater usually contains high salt dosages, residual dyes and chemical auxiliaries, which may cause serious health issues and disturb the ecological balance.…”