with Egyptian Mallow Leaves

Heba F. Mansour, and Khaled K. K., Department of Textile Printing, Dyeing and Finishing.
Faculty of Applied Arts, Helwan University, Giza, Egypt.

Abstract

Nowadays, environmental awareness is an essential aspect of textile dyeing technology. With this trend in mind, the present work studied the eco-friendly dyeing of woollen fabric with extracts from Egyptian Mallow leaves.

Wool specimens were subjected to albumen treatment before dyeing. Several factors affecting dye absorption were examined in order to optimize the dyeing conditions. Modification of the wool surface by albumen treatment showed proper development of the colour yield, in addition to satisfactory fastness properties.

1-Introduction

To ensure the environmental adequacy in textile dyeing technology, natural dyes are discovered as an ‘’Eco-solution'’ to the hazardous effects of synthetic dyes. (1).
Natural dyes are extracted from a variety of plants as well as animals sources. The most common used source is plants. The classification and chemistry of these natural dyes with respect to colour were mentioned before. (2-3). Green natural dyes are rarely examined; the only mentioned green dyes were, Cascara Sagrada ( Natural Green 2) and Gurhal dyes (3-4).

Egyptian mallow is one of the national dishes in Egypt, it is a mucilaginous, nutritious green soup made from crushed green leaves (5). The plant is  cultivated  in Egypt, Syria as a pot herb, and in India (6). The Arabic name of this dish  is molokheya, and it is transliterated to several forms as, Moulokheyya, Mulukheyya, Mooookhieh, Mouloukhia, Mloukhia, Molohia, Molokhiya, Molukhyia, Mulukhia, Mulukhiya, Melokiyah, Meloukhia, and other variations. The English names expressed as Jew’s Mallow, Jute Mallow,and Nalta Jute (7). The Latin name for this plant is Corchorus Olitorious, its family name is Tiliaceae, and its Botanical references is 200 (8-10).

Some people believe that Molokheya is originated amoung Egyptians during the time of Pharaohs. Other suggest that it was prepared first by ancient Jews. It is said that the original name for molokheya is Mulukeyya, which means “of the kings”, then the public turned the “K” to the present “KH”. Molokheya has been mentioned in Arab medieval historical texts, and played a part in folklore, especially in 399 A.H, and 418 A.H (7). 

Moloukhia is a tall leafy herb. The leaves are used as potherb, spinach or as salad, they are lance late and serrate, which are used fresh and dried. In Egypt and the Middle East, Molokhia is used in soups, in India, it substitutes spinach, and in the Caribbean it is a salad. Sometimes Molokhia is used as a source of Jute, but C.Capsularis is the more important source of  this fibre (11).

In this study, the dried green leaves of the Egyptian Mallow were used to produce a novel natural green / yellow dye. Egg albumen was used as a source of natural mordant for dye fixation to overcome the toxicity, and the red listed chemical mordants (12).
Treating wool with egg albumen before dyeing with Egyptian Mallow leaves was examined to confirm the chemical free wool dyeing technology, so that the product appeal to the green minded consumer is reinforced.

2- Experimental

2-1- Material

100% mill scoured fabric was obtained from the local Egyptian market.  The fabric was further scoured with a solution containing 2g/l sodium carbonate, and 2g/l non-ionic detergent (Hostapal CV, supplied by Dyestar).

Scouring process was done at 60± 2oC for 30 minutes using liquor to ratio L. R. 1:50.  The fabric was then thoroughly washed in warm and cold water, then was dried at ambient temperature.

2.2- Dyestuff

2-2-1- Extraction of the Dye

50 gms of crushed dry leaves of Egyptian Mallow were extracted in (200 ml) ethanol in soxlet for 15 hours. The extract was filtered off, and  was evaporated under reduced pressure to make the volume to 20 ml. The solution was used in making thin layer chromatography.

Another 50 gms of crushed dry leaves of the Egyptian Mallow were extracted in (200 ml) water for an hour at boiling. The aqueous extract was filtered and used directly for dyeing wool.

2-2-2- Chemical Constituent of the Dye

Thin layer chromatography was used to determine the pigments found in the Egyptian Mallow extract (13).

2-3- Egg Albumen Treatment
Egg albumen was stirred and diluted with water at different concentrations as follows:

1-         25% albumen + 75% water

2- 50% albumen + 50% water

3-         75% albumen +25% water

4- 100% albumen

Wool specimens were impregnated in each of the previous mentioned concentrations separately for 30 minutes at room temperature. After that, the specimens were padded and dry at 100oC for 3 minutes.

2-4- Dyeing Process

Untreated, and treated wool specimens were conventionally dyed by the Egyptian Mallow aqueous extract. The dyeing process was taken place for an hour, at 85oC, at liquor to ratio 1:50. The pH of the dyeing bath was detected at 3, 5,and 7. Adjustment of pH values was done using lemon juice.

2-5- Washing

After dyeing, wool specimens were washed according to the procedure indicated in Table 1, hence earlier trials observed no fastness development from higher temperature washing, all hot washing were performed at 60oC. The washed samples were dried at 100oC  (14)

2-6- Measurements

2-6-1- Colour Strength

Colour strength of the dyed specimens in terms of K/S values was obtained by using Ultra Scan XE apparatus. The K/S values for each specimen computed by Kubelka Munk equation (15)

2-6-2- Colour Fastness

Colour fastness to rubbing (dry & wet) was determined using the manual crockmeter as per the BIS norms (IS: 766-1956), and was assessed using the Grey scale as per ISO-105-AO3 (extent of staining).

Fastness to washing of the dyed samples was determined using Sasmira Launder-O-Meter as per ISO-II wash method and was assessed by the grey scales as per ISO-105-AO2 ( loss of shade depth) and ISO-105-AO3 ( extent of staining) (16) .
Colour fastness to light was determined as per BS-1-6:BOI-1978, using SDL-MBTF lamp-microsal light fastness tester (16) .

3- Results and Discussion

3-1- Mallow Dye Extract

From the thin layer chromatography, it was denoted that, Egyptian mallow extract contains green and yellow pigments. The green pigment is chlorophyll, and the yellow one is xanthophylls. Figure-1 represents the two pigments.

Chlorophyll (17)  is a green pigment, does not contain reactive groups to react with wool. On the other hand, xanthophylls (18)  is one of the carotenoids which contain hydroxyl groups . Scheme1 represents the chemical structure of two pigments.

Wool contains a number of reactive groups capable for attracting the dye molecules, the dye affinity depends on the particular reactive sites in wool and dye (19) .
In case of the untreated specimen, There was no reaction between wool and chlorophyll and the specimens appeared in yellow colour. Xanthophylls exhibits good affinity on wool fibres due to the presence of hydroxyl groups. Inside the fibre, the anions (OH) groups of the dye extract attract with the sites near the positively charged basic groups of wool, forming ionic bonds (20) .On the other hand, hydrogen bonding occurs between the xanthophylls and the amino groups of wool (21) .

In addition, Vander Waal’s force plays an important role in binding. This depends on the great polymerization and the length of the conjugated chain of xanthophylls, which leads to the strong substantively of xanthophylls molecules with wool (20)

3-2- Egg Albumen Treatment

Figure 2: represents the effect of with egg albumen treatment at different concentrations on the colour strength of wool, dyed with Egyptian Mallow extract.
It was observed that; albumen increases the dye uptake. The colour strength reached its highest value at concentration (25% egg albumen\75% water), then decreased gradually by increasing the concentration.

Egg albumen is a mixture of numerous proteins, Table 2 represents the amino acid content of the major egg albumen protein and indicates which proteins polar (p), basic (+), or acidic (-), also the amino acids which contain sulpher (22).
 
As a group, albumens are generally soluble in water and coagulated by heat. Heat induced denaturation also result in mild conformational changes and polymerization due to disulphide formation and\ or sulph-hydryl- disulphide ( SH-SS) interchange. Egg albumen was used as a binder, while having an affinity for the colouring matter, it is slightly combine with the fabric chemically, but rather adhere to them mechanically through heat fixation (23-24). It may be attracted with wool during treatment, either by forming peptide linkage, or through adhesion by heating. Scheme 2 represents the mechanism of reaction between wool and egg albumen. On the other hand, it may be fixed the chlorophyll pigment with wool by adhesion, and xanthophylls pigment either by adhesion or forming sites of anion adsorption , between the positively charged wool and the negatively charged xanthophylls. In addition to, Vander Waal’s force which plays an important role in binding. The mechanism of reaction was illustrated in scheme 2. Albumen was defined as one of the natural mordant (22-23)., so it has the ability to fix the Egyptian Mallow extract in wool. Scheme-3 represents the mechanism of reaction between the two pigments and wool in absence and presence of  albumen.

3-3- PH

Figure 3: represents the effect of the different pH values on the colour strength of untreated and albumen treated dyed wool. It was observed that, in case of theuntreated specimen, the colour strength reached its maximum value at pH 5 and its minimum one at pH 7. In case of albumen treated specimen, the maximum colour strength values were nearly equal at pH 5 and 7.

Very great swelling of untreated and treated wool occurs in the acidic medium, where the hydrogen atoms of the citric  acid in the lemon juice will replace some of the cross linking hydrogen bonds between the amino and (OH) groups, thus reduce the cohesion of the wool fibre, facilitating the penetration of the dye extract molecules (24).

The dye extract can be reacted with wool by  the anionic linkage, which  increases   the electrical potential that builds up in  wool , this facilitates the penetration of (H) ions,  therefore increases the affinity of wool to the dye extract, which accompanied by an increase in the colour strength (20). In the neutral medium, the colour strength of the treated wool was maximum, this is because treatment with albumen gives additional sites to wool, so, the isoelectric point was changed, resulted in an increase in the dye ability of the treated wool (24). 

  4- Fastness Properties

The fastness properties were found to be dependent on treating wool with egg albumen, as shown in Table 3. Wool specimen treated with egg albumen exhibits  a considerable improvement in the different fastness properties.

4-1- Rubbing Fastness

It was denoted that, the untreated dyed specimen showed fair to good dry rubbing fastness, in compared with the albumen treated one which represented  good  rubbing fastness. In wet rubbing fastness, the untreated dyed specimen showed fair rubbing fastness in compared with the albumen treated one which represented fair to good  rubbing fastness. Rubbing causes the removal of loosely adhered dye molecules which are most probably present as deposited layers on the fibre surface, while those forming intermolecular hydrogen bond, or dispersed throughout the fibre with high molecular weight are not removed by rubbing (20). Wet rubbing represents lower rubbing fastness in compared with the dry rubbing one, this may be  due to; the decomposition of dye molecules and  breaking of the dye-fibre bond in presence of water during rubbing.

4-2- Washing Fastness

Treated wool, dyed with Egyptian mallow extract has shown good to excellent washing fastness in compared with the untreated one which had shown good fastness. The staining test indicated negligible staining to noticeably staining in case of the treated specimen, and slight to noticeably staining in case of the untreated one.

Dyeing with natural dyes in absence of mordants gives poor washing fastness, as the dye is attached to the fibre through reversible forces such as ; hydrogen bonds and other weak forces of attraction which are easily overcome. Superior washing fastness in presence of mordant is due to the ability of the dye molecules to aggregate into large particles in the fibre without formation of any additional forces (4).

4-3- Light Fastness

The light fastness of the untreated dyed specimen exhibited fair to good light fastness. The particular amino acid residues in wool retard the photo-oxidation of the dye by reacting preferentially with oxidants generated on exposure of the coloured fibre (27). There was a slight improvement in light fastness when treating wool with albumen, the light fastness exhibited good result.

 
The increase of light fastness may be due to a reduction in the surface activity of the dye molecules and the increase of the dye- fibre bond strength.

Conclusion

Egyptian Mallow extract opens width for a new source of natural yellow and green dyes. Mallow dye has high affinity for woolen fabrics, and it is capable of dyeing in yellow shade in absence of albumen, depending on the xanthophylls pigment. Pre-treatment of wool with egg albumen increases the dye uptake and facilitate the chlorophyll pigment to combine mechanically with wool by adhesion giving green shade to the treated specimen. Egg albumen treatment give a chance to dye woolen fabrics in the neutral medium. On the other hand, albumen treatment enhance the different fastness properties of wool dyed with mallow dye. Finally, it is available to dye woolen fabrics with chemicals free dyeing, confirming the product appeal to the green minded consumer.

Future of Work

The authors have a further strategy plane to examine the following research points:
1- Dyeing and printing different fabrics such as cotton, natural silk, linen, viscose, and mixed fabrics with the Egyptian mallow leaves.

2- Using different safety mordants as tannic acid, alum, oils, vinegar, and lime water in mordanting the different types of fabrics when using the Egyptian mallow leaves.

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