IMPACT OF CHITIN AN ECO-FRIENDLY MORDANT ON NATURAL DYES
Loading...
Files
Date
2004
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY RAJENDRANAGAR, HYDERABAD
Abstract
With increasing awareness of the environmental pollution and health hazards
associated with the use of synthetic dyes on textiles involving eco-friendly processes
of dyeing textiles has become imperative. Due to the ban by Germany on the use of
azo dyes in textiles garments imported to Germany, quite some excitement has come
to prevail in the textile processing sector with regard to the use of dyes that pass
through eco-standards. This has facilitated the revival of natural dyes into focus. The
expertise in extraction, dyeing and printing of textiles with natural dyes that was
developed and patronized by Indian artisans was not known to the present
generations. Hence, research is going on to overcome the limitations of natural dyes.
Generally natural dyes produce shades that are fugitive in nature. Hence,
mordants are used for fixation of the dye onto the fabric. Alum, ferrous sulphate,
chrome, copper, stannous chloride are the mordants generally employed for dyeing
with natural dyes. According to the eco-standards, chrome and copper are red listed
whereas alum and ferrous sulphate are considered as eco-friendly. Hence, research is
presently focused on identification and standardization of eco-friendly mordants for
natural dyes. The available literature indicated that, there was no research work
previously done on chitin as a mordant on natural dyes. Chitin is a natural
polysaccharide obtained from shells of crustaceans, exoskeleton of insects etc. There
is research evidence that it contributes to synthetic dye fixation. Taking into
consideration of the above facts, the present study was undertaken to use chitin as an
eco-friendly mordant for four selected dye sources on cotton and assess their
colourfastness.
Mercerized cotton yarn was selected for the study on the effect of chitin
mordant as it facilitates better absorption. Four dye sources were selected namely
Tagetus erecta, Onosma echinoides, Peltaphorum pterocarpum and Rubia cardifolia
on cotton. Mordants such as alum and ferrous sulphate were used for comparision
with chitin.
The cotton yarn was pretreated with myrobalan to increase the depth of the
shade obtained. The standard extraction and dyeing conditions of the selected dyes
were adopted from the research work of scientists of AICRP-CT on Home Science,
ICAR. The optimization of the chitin mordant concentrations was done based on the
optical density before and after dyeing. The observations of the optical density were
recorded at the maximum wavelength of the dye source mentioned above.
The concentration levels of 1, 2 and 3 per cent were selected in case of
mordanting with chitin for dyeing with Tagetus erecta, Peltaphorum pterocarpum and
Rubia cardifolia and 3, 4 and 5 per cent concentration levels were selected for
Onosma echinoides dye. The mordant concentrations of 5, 10 and 15 per cent for
alum and 1, 2 and 3 per cent levels for ferrous sulphate were selected for mordanting
and used for comparision with the samples dyed with chitin (adopted from AICRPCT,
ICAR).
The dyed cotton samples with chitin mordant had produced soft, lustrous and
pastel shades. Chitin mordanted samples dyed in Tagetus erecta exhibited dark green
to dull khaki shades. Colours ranging from dull grey to moderate grey shades were
obtained by dyeing with Onosma echinoides. The cotton samples dyed in
Peltaphorum pterocarpum produced creamish brown to moderate brown shades using
chitin mordant. The dye extracted from Rubia cardifolia has shown peach to pinkish
shades on cotton mordanted with chitin.
Alum produced dark shades compared to chitin. Grey tones were produced
with ferrous sulphate. Brownish shades were produced using alum mordant and green
to greyish brown shades were obtained with ferrous sulphate when dyed in Tagetus
erecta dye. Cotton mordanted with alum exhibited greyish blue colour with greenish
tinge and greyish blue to brown shades were produced on samples mordanted with
ferrous sulphate. Peltaphorum pterocarpum had exhibited biscuit brown to moderate
brown shades and moderate to dark brown shades with alum and ferrous sulphate
respectively. The dye extracted from Rubia cardifolia produced pinkish brown with
alum mordant and pinkish grey shades with ferrous sulphate mordant.
The cost of dyeing with chitin mordant is high when compared to other
mordants. Even though, the cost is high the eco-friendliness and high curative
properties of chitin mordant will be a breakthrough in the technology of dyeing with
natural dyes.
Description
Keywords
IMPACT, CHITIN, ECO-FRIENDLY, MORDANT, NATURAL, DYES