Читать книгу Sustainable Practices in the Textile Industry - Группа авторов - Страница 26

Bio-mordants are those substances that can be obtained from natural sources. According to many researchers bio-mordants are eco-friendly and effective to use than synthetic mordants [40]. There are some examples of bio-mordants:

1 i. Myrobalan: It is one of the most important and widely used mordants in dyeing processes. It can be considered as dye and mordant both. Myrobalan mordant is obtained from fruits of Terminalia chebula commonly known as ‘Harda’. It gives pale yellow color on fabric.

2 ii. Oak gall: Gallnuts are obtained from the oak tree. It is the earliest and richest source for natural tannin. These are collected and ground for use as a tannin mordant.

3 iii. Sumac: The leaves of sumac contain tannin which can be used in the process of mordanting cotton. Rhus glabra species of sumac also known as “rhubarb”. Leaves of sumac are rich in tannin suitable for dyeing and their use as mordant.

4 iv. Pomegranate rind: Dried pomegranate rind (P. granatum) powder also used as mordant in natural dyeing. Sangeetha et al. applied lemon leaves extract using P. granatum rinds as mordant on Silk fabric [41].

5 v. Catechu: Catechu was used as a natural mordant since the ancient times as myrobalan [42, 43]. Catechu is extracted from the heartwood of Acacia catechu. It produces various shades of brown. Catechu mordants were applied with Sticta coronate a lichen that produces dye for coloring silk fabric [42].

6 vi. Aloe vera: Aloe vera leaves contain sticky substance. Researchers are working on exhibited fixing properties of aloe. Fresh leaves of aloe vera can be taken as biomordant for dyeing silk fabric [44].

Other than above mentioned names many sources have been explored for bio-mordants. Adeel et al. explored the fixing properties of acacia (Acacia nilotica), henna (Lawsonia inermis), turmeric (C. longa), pomegranate (P. granatum) and rose (Rosa indica) with natural dye extracted from cinnamon bark. New shades observed on silk fabric with improved fastness properties [45]. Bark of Xylocarpus moluccensis tested to be used as a biomordant, and significant improvement in the percentages of dye absorbed in the silk fabric was observed [46]. Wool yarn dyed with madder roots with gallnut (Quercus infectoria) extract as biomordant [47]. Rani et al. investigated that harda powder, pomegranate peel, orange peel and amla powder can be used as alternative copartner of metal mordants. Dyeing was done on protein fabrics with Carica papaya leaf natural extract [48]. Wool yarn dyeing performed with Adhatoda vasica extract. The effect of various metal salts and extracts of gallnut, pomegranate peel and babool bark as mordants were comparatively evaluated [49]. Aminoddin extracted Berberine from Berberis vulgaris wood and applied on wool fiber using the extract of roots of Rumex hymenosepalus as biomordant [50]. Banana pseudostem sap was applied as a biomordant with Senegalia catechu stem extract on wool [51]. To provide best options of synthetic mordants various scientists are exploring and developing the new and effective bio-mordants.