colours or molecules which have the ability to absorb
or reflect the visible part of light at a specific wavelength, imparting to the human eye a sense of colour.
Dyeing is a process of imparting beauty to the fabric by
applying many colours and their shades in the textile
(Daberao, Kolte, & Turukmane 2016). Natural dyes
are colourants, which are derived from plants, invertebrates, minerals, and organic sources such as fungi
and lichens. These dyes are used for colouring textiles,
food, and other materials. They are environmentally
friendly, biodegradable, and their by-products can be
used as fertilisers.
The textile industry is the largest consumer of
dyestuffs. During the process of colouring, most of
the synthetic dye does not adhere to the fabric, and
hence is lost in the waste stream, thus effluents from
the textile industry carry a number of dyes and also
other additives which are added during the colouring
process (An et al. 2017). These are difficult to get
rid of, thus they are transported to sewers and rivers.
They are highly water soluble and may also undergo
degradation to form other by-products that are highly
toxic and carcinogenic in nature. It is only in the textile industry that the largest amount of aqueous wastes
and dye effluents are released from the dyeing process
with both strong and persistent colour and highly biological oxygen demand (BOD), both of which are not
environmentally friendly and are unacceptable (Singh
& Arora 2011).
According to Mozumder and Majumder (2016),
natural dyes gained usage due to environmental awareness,. These natural dyes are better in terms of
biodegradability, good for ultraviolet protection, antibacterial activity, and have the best compatibility with
the environment. Most dyes from natural sources are
not substantive and they require the use of mordants to
fix the dye properly on the fabric. The colour fastness
of natural dyes is different based on the method used
and the application used. Hence this study will use the
best possibilities and methods of dyeing cotton fabric.
The colour fastness property depends on the selection
of the dye type to the type of the fabric to be applied
(Mozumder & Majumder 2016). Thus during application, the choice and method yields different results in
terms of colour fastness.
Lichens are organisms which are pleasant to the eye.
They are symbiotic organisms composed of algae and
fungi, which together form an independent and unique
physiological unit (Shaheen, Iqbal, & Hussain 2019).
They grow in terrestrial habitats like on trees, rocks,
and soil. Their slow growth and harsh living conditions are due to the fact that they produce secondary
metabolites, which are the main source of natural dyes.
The first dye producing lichen was from a species of
Rocella which produced a purple dye colour through a
fermentation method of extraction. Lichen dyes have
despides and despidones that are composed of two
or three phenolic groups and are formed through the
acetate–polymelonate pathway by the phycobiont partner. These are the sources of dyes from lichens which
are mainly used to dye natural fabrics. As they grow
on tree trunks, branches, and twigs of trees and rocks,
unfortunately many people have not identified or used
them due to lack of information on their importance,
which is why they are unnoticed and unexplored.
Natural dyes are classified according to their
source, i.e., (a) from plants: flowers, bark, leaves, and
seeds; (b) from insects; (c) from minerals; and (d) from
fungi. These natural colours are due to chromophores.
Dyes are also classified as reactive dyes, vat dyes,
azo dyes, direct dyes, and alkaline dyes (Benkhaya,
Harfi, & Harfi 2018). These authors classified natural dyes according to their classes, application, and
also principles, thus natural dyes are classified according to the chemical structure or according to their
application on the textiles. Another classification of
natural dyes is into three classes: (a) natural dyes
from plants, e.g., indigoid; (b) those obtained from
animals, e.g., cochineal; and (c) those obtained from
minerals, e.g., ochre. Jihad (2014) stated that these
dyes are safe due to their non-toxic, non-carcinogenic,
and biodegradable nature and are grouped into three
types: (a) substantive dyes which link directly with the
fabric during dyeing process—this type of dye does
not require mordants to fix the dye into the fabric as
they contain their mordants in the dye structure, e.g.
extracts of tea, walnut, and onion; (b) traditional dyes
which consist of natural dyes that require mordants
to form a link between the dye and the fabric; and
(c) according to the dye chemical composition and
hue.
The methods of extraction of natural dyes are
found through trials of different methods. Mphande
and Pogrebnoi (2014) used three extraction methods:
Soxhlet, aqueous, and cold soxhlet extraction methods
for the extraction of natural dyes. They found out that
cold ethanol and hot soxhlet extraction methods gave
the best results.
Ain, Sakinah, and Zularisam (2016) extracted
anthroquinones from the roots of Marinda citrifolia
using a solvent extraction method, which the authors
described as the best and most convenient method as
it is widely used for the extraction of natural dyes.
The method is referred to as a safe and easy method
of natural dye extraction compared to other methods.
It has two phases: liquid (solvents) and solid (plant
matrix), and two extraction processes whereby there
is transfer of solute from plant material to the solvent by diffusion and osmotic pressure. The type of the
solvent, pH, extraction time, and techniques of extraction are the factors that determine the quantity of the
analyte.
According to Shaheen et al. (2019) the following extraction methods were used in the extraction
of dyes from lichens: cow urine method (CUM),
boiling water method (BWM), ammonia fermentation method (AFM), and dimethyl sulfoxide extraction
method (DEM). It was reported that the three extraction methods gave different colours upon dyeing of
silk fabric, with AFM being the best method of extracting natural dyes from lichens as it gave the brightest
colours.
126
or reflect the visible part of light at a specific wavelength, imparting to the human eye a sense of colour.
Dyeing is a process of imparting beauty to the fabric by
applying many colours and their shades in the textile
(Daberao, Kolte, & Turukmane 2016). Natural dyes
are colourants, which are derived from plants, invertebrates, minerals, and organic sources such as fungi
and lichens. These dyes are used for colouring textiles,
food, and other materials. They are environmentally
friendly, biodegradable, and their by-products can be
used as fertilisers.
The textile industry is the largest consumer of
dyestuffs. During the process of colouring, most of
the synthetic dye does not adhere to the fabric, and
hence is lost in the waste stream, thus effluents from
the textile industry carry a number of dyes and also
other additives which are added during the colouring
process (An et al. 2017). These are difficult to get
rid of, thus they are transported to sewers and rivers.
They are highly water soluble and may also undergo
degradation to form other by-products that are highly
toxic and carcinogenic in nature. It is only in the textile industry that the largest amount of aqueous wastes
and dye effluents are released from the dyeing process
with both strong and persistent colour and highly biological oxygen demand (BOD), both of which are not
environmentally friendly and are unacceptable (Singh
& Arora 2011).
According to Mozumder and Majumder (2016),
natural dyes gained usage due to environmental awareness,. These natural dyes are better in terms of
biodegradability, good for ultraviolet protection, antibacterial activity, and have the best compatibility with
the environment. Most dyes from natural sources are
not substantive and they require the use of mordants to
fix the dye properly on the fabric. The colour fastness
of natural dyes is different based on the method used
and the application used. Hence this study will use the
best possibilities and methods of dyeing cotton fabric.
The colour fastness property depends on the selection
of the dye type to the type of the fabric to be applied
(Mozumder & Majumder 2016). Thus during application, the choice and method yields different results in
terms of colour fastness.
Lichens are organisms which are pleasant to the eye.
They are symbiotic organisms composed of algae and
fungi, which together form an independent and unique
physiological unit (Shaheen, Iqbal, & Hussain 2019).
They grow in terrestrial habitats like on trees, rocks,
and soil. Their slow growth and harsh living conditions are due to the fact that they produce secondary
metabolites, which are the main source of natural dyes.
The first dye producing lichen was from a species of
Rocella which produced a purple dye colour through a
fermentation method of extraction. Lichen dyes have
despides and despidones that are composed of two
or three phenolic groups and are formed through the
acetate–polymelonate pathway by the phycobiont partner. These are the sources of dyes from lichens which
are mainly used to dye natural fabrics. As they grow
on tree trunks, branches, and twigs of trees and rocks,
unfortunately many people have not identified or used
them due to lack of information on their importance,
which is why they are unnoticed and unexplored.
Natural dyes are classified according to their
source, i.e., (a) from plants: flowers, bark, leaves, and
seeds; (b) from insects; (c) from minerals; and (d) from
fungi. These natural colours are due to chromophores.
Dyes are also classified as reactive dyes, vat dyes,
azo dyes, direct dyes, and alkaline dyes (Benkhaya,
Harfi, & Harfi 2018). These authors classified natural dyes according to their classes, application, and
also principles, thus natural dyes are classified according to the chemical structure or according to their
application on the textiles. Another classification of
natural dyes is into three classes: (a) natural dyes
from plants, e.g., indigoid; (b) those obtained from
animals, e.g., cochineal; and (c) those obtained from
minerals, e.g., ochre. Jihad (2014) stated that these
dyes are safe due to their non-toxic, non-carcinogenic,
and biodegradable nature and are grouped into three
types: (a) substantive dyes which link directly with the
fabric during dyeing process—this type of dye does
not require mordants to fix the dye into the fabric as
they contain their mordants in the dye structure, e.g.
extracts of tea, walnut, and onion; (b) traditional dyes
which consist of natural dyes that require mordants
to form a link between the dye and the fabric; and
(c) according to the dye chemical composition and
hue.
The methods of extraction of natural dyes are
found through trials of different methods. Mphande
and Pogrebnoi (2014) used three extraction methods:
Soxhlet, aqueous, and cold soxhlet extraction methods
for the extraction of natural dyes. They found out that
cold ethanol and hot soxhlet extraction methods gave
the best results.
Ain, Sakinah, and Zularisam (2016) extracted
anthroquinones from the roots of Marinda citrifolia
using a solvent extraction method, which the authors
described as the best and most convenient method as
it is widely used for the extraction of natural dyes.
The method is referred to as a safe and easy method
of natural dye extraction compared to other methods.
It has two phases: liquid (solvents) and solid (plant
matrix), and two extraction processes whereby there
is transfer of solute from plant material to the solvent by diffusion and osmotic pressure. The type of the
solvent, pH, extraction time, and techniques of extraction are the factors that determine the quantity of the
analyte.
According to Shaheen et al. (2019) the following extraction methods were used in the extraction
of dyes from lichens: cow urine method (CUM),
boiling water method (BWM), ammonia fermentation method (AFM), and dimethyl sulfoxide extraction
method (DEM). It was reported that the three extraction methods gave different colours upon dyeing of
silk fabric, with AFM being the best method of extracting natural dyes from lichens as it gave the brightest
colours.
126