Sustainable chemistry method to improve the wash-off process of reactive dyes on cotton
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Date
2015
Authors
Journal Title
Journal ISSN
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Publisher
ACS Sustainable Chemistry & Engineering
Abstract
Reactive dyes are extensively used for coloration of
cellulosic fibers because of their excellent wash fastness (stability to
washing with aqueous detergent solutions), which arises from
covalent bond formation between dye and fiber. However, up to
40% of the dyestuff may hydrolyze in the dyeing process; this
hydrolyzed dye has affinity for the fiber via hydrogen bonding and
van der Waals interactions, but is not covalently bonded and as such
exhibits poor wash fastness. Accordingly, these reactive dyeings
require a multistep “wash-off” process after dyeing, involving various
aqueous rinses and washings, in order for the dyeing to achieve the
characteristic very high wash fastness. Wash-off and subsequent
effluent treatment can account for up to 50% of the total cost of
reactive dyeing and consumes significant amounts of water and
energy; from a sustainable chemistry and engineering perspective,
consumption of water and energy are arguably the biggest issues in textile dyeing. Existing and developmental dye transfer
inhibiting (DTI) polymers were employed to remove unfixed (hydrolyzed) dyes. It was found that the use of DTI in the wash-off
of reactive dyes enables a much more efficient, economical and sustainable process to be developed, which significantly reduces
operation time, water consumption and energy consumption. Different DTI polymer types varied in their efficacy of dye removal;
poly(vinylpyridine-N-oxide) polymers were the most effective with respect to the level of hydrolyzed dye removal closely
followed by the poly(vinylpyridine betaine) polymers, which were also highly efficient in hydrolyzed dye removal, with
poly(vinylpyrrolidone) polymers being the least effective. These differences were attributed to variations in the magnitude and
delocalization of positive electrostatic potential of the functional moieties in the polymers and the extent of and propensity for
hydrogen bonding with the hydrolyzed reactive dyes.
Description
Keywords
Reactive dyes, Wash-off, Water, Energy, Hydrolyzed dye, Dye transfer inhibiting polymers
Citation
Amin, M. N., & Blackburn, R. S. (2015). Sustainable Chemistry Method to Improve the Wash-off Process of Reactive Dyes on Cotton. ACS Sustainable Chemistry & Engineering, 3(4), 725-732.