Author mohamed mohamed mosaad
The application of aloe vera in textile processing is gaining worldwide detection as one of the hopeful approaches to pollution issues and cost reduction. Aloe vera gel possesses some biological activities and unique properties such as colorless, transparent, and viscosity which meet the using as a printing thickener, mordant, antimicrobial for different fabrics and dyes. Aloe vera is used in pre-treatment such as scouring, desizing, softening, and printing due to its succulent enzymatic and gummy characteristics. Aloe vera gel also contains a salty substance that allows its use in natural, eco-friendly dyeing. Aloe vera gel also is an alternative to synthetic antimicrobial agents. Textile wet processing utilizes a huge amount of water, dyes and chemicals, and other auxiliaries for processes. It can be considered as having three stages, pretreatment (or preparation), coloration (dyeing or printing) and finishing. Textile wet processing industry is one of major cause of environmental pollution. Because it is included a toxic, hazardous, and less bio-degradable compounds which is a major source of effluents and pollution. Searching for ecofriendly alternatives is a main concern of most researchers. Natural resources are gaining global recognition because of their nontoxic and eco-friendly characteristics with the increasingly important requirements for textile manufacturers to reduce pollution in textile production. Rheological behavior of Aloe vera gel. Aloe vera gel generally exhibits elastic behavior which can be attributed to the network of polymeric fibrous chains. Viscosity decreases with increasing shear rate (exhibiting shear thinning behavior); however, above certain critical value (100 S ?1) viscosity becomes constant. Such rheological behavior is attributed to the structural decomposition and rearrangement of weak network of polymeric fibers. Rheology of any formulation such as paste depends upon the combination of individual components as well as their mutual interactions. The addition of Aloe vera gel to different products can lead to complex rheological behaviors, developing from its interactions with product ingredients as well as process conditions. However, the rheological properties of Aloe vera can be tuned to meet product requirements. Moreover, it can also be used as a rheology modifier for various products. Aloe vera is used in pre-treatment and printing due to its succulent enzymatic and gummy characteristics. Aloe gel also contains a salty substance that allows its use in natural, eco-friendly dyeing and finishing. There are many actual and potential applications of Aloe vera in textiles wet processing field. To meet customer demand, A huge amount of inorganic chemicals are used in textiles pretreatment, dyeing, printing, and finishing. Since, the use of these chemicals produces a huge amount of effluent but causes water pollution, researchers have been trying to use eco-friendly products like Aloe vera instead of inorganic chemicals for these purposes to protect the environment from this pollution. Aloe vera is suitable for such pretreatment because it contains many enzymes, salt and gummy substances which are essential for textile wet processing. Bio Scouring with aloe vera, scouring process was used to remove the non-cellulosic impurities from the cotton to have a uniform absorbency. Highly alkaline chemicals like caustic soda, soda ash, silicate, acetic acid, and soaping agents are used for scouring, but destruction of cotton structure may be happened also attack the cellulose leading to heavy strength loss and weight loss in the fabric. Moreover, the need for intensive rinsing and more acid to reutilization the cotton, which leads to a large volume of effluent. Optimum condition of bio scouring with enzyme, requires treatment with concentration 5% at pH 5.5 at 80?C for 1 hour. Bio-scoured fabrics, using the Aloe vera extract, showed better dye levels, dye uptake, light fastness, wash fastness, and rubbing fastness for medium and dark reactive colors than did conventionally scoured fabric. Bio-scouring saved a substantial amount of thermal energy (50%) and electrical energy (40%). Bio-scouring wastewater has 4050% less COD and 60% fewer TDS than conventional-scouring wastewater does. Bio scouring with enzyme is corresponding with a significant role in minimizing the demand of energy, water, chemicals, time and therefore costs. After bio scouring, fabric can be dyed directly without bleaching, which also reduces additional cost in this step. But in this process, light-colored shades cannot be produced or very difficult match. Enzymatic Desizing with aloe vera: For the improved and uniform wet processing of the fiber, starch-based size is needed to be removed prior to dyeing and printing, this is known as desizing, which is the key action of the pretreatment. As converts the water insoluble starch in to the soluble one which is washed away from the fabric during washing and enhances the performance of the fabric. Since enzymes are widely used in desizing which called Enzymatic desizing. These enzymes catalyze the breakdown of the starch chain without damaging the support material as their action is specific to starch. Desizing process using Aloe vera gel instead of inorganic chemicals. Since Aloe gel contains many important enzymes and organic components like peroxidase, carboxypeptidase, amylase, and alkaline phosphatase. The aloe gel has been showed outstanding results for desizing with controlled temperature and pH. The aloe gel treated fabric was exhibited high desizing efficiency. This is due to key-Lock mechanism of enzymes presents in the aloe gel. When we compare the desizing efficiency of synthetic enzyme and aloe gel enzyme (natural enzyme amylase) the weight loss is greater that means the weight loss in synthetic enzyme desizing is 7.9% and in aloe gel case it is 11.02% so it has good desizing efficiency but aloe gel desizing have side effect of coloring salt. These aloe vera enzymes have active centers, which fits into a particular substrate molecule. Then the substrate forms a complex with the enzyme. Later the substrate molecule is converted into the product and the enzyme itself is regenerated. The process continues until the enzyme is poisoned by a chemical bogie or inactivated by extremes of temperature, Ph. Aloe vera gel which used instead of salt in a reactive dyeing process. Since aloe vera consists of salt, acid, enzymes, and many components that are essential to the dyeing process, aloe gel have been used to present sodium ion on dyeing cotton with reactive dye without salt. Aloe gel treated cotton fabrics, was dyed with different types of reactive dyes without addition of sodium chloride with different concentration of aloe gel. Treated sample was compared with normal dyed untreated sample. The fabrics treated with 100% aloe gel have good and highest shade depth, 80% aloe gel treated fabrics has medium, while the 60% aloe gel treated fabrics have lowest. increasing the concentration aloe gel led to increase the amount of sodium ion and therefor increase dye bath exhaustion so the dye uptake of the fabrics is higher. on a high concentration of Aloe vera contains more salt than dye does. Treatment of cotton fabric with aloe gel increases dye uptake of cotton at low salt condition without decreasing the wash fastness. Some reports discuss using Aloe vera as a mordant for dyeing of turmeric powder on cotton and silk fabric. Aloe vera gel as thickening agent on Printing: Printing is most important process used to decorate textile materials. Textile printing is localized dyeing in definite patterns. A successful print involves correct color, sharp-line, levelness, good hand, and efficient use of dye; all these factors depend on the type of thickener used. Thickening agents usually high molecular weight polymeric substances that give the necessary viscosity of the color printing paste under high pressure, without distortion. Textile thickeners either natural (e.g., Arabic gum, guar gum, alginate, starch, etc.) or man-made (i.e., based on modified natural polymers or wholly synthetic polymers, or emulsion). The use of synthetic thickeners causes harmful effects in the environment, to reduce and avoid this effect an eco-friendly thickener can be used. Aloe vera gel possesses some unique properties such as colorless, transparent, and viscous which meet the using as a printing thickener for different fabrics and dyes. Aloe vera gel as thickener with reactive dye on cotton. Since the conventional thickeners such as starch, CMC, guar gum contains free -OH groups, are not suitable for printing cotton with reactive dyes. because of these free hydroxyl groups which competes with the free hydroxyl group of cellulose toward dye. whereas Sodium alginate is suitable because it is free from free -OH groups. the same trend in aloe vera which contains (galacturonic acid) important used as thickener because which is free from -OH groups. Many attempts to use aloe vera as thickening agents had been reported. Aloe vera gel in combination with sodium alginate as a thickener to suit printing cotton fabric with reactive dyes. Three different types of thickeners combination, aloe vera gel (AG), Sodium alginate (SA) and Mixture of aloe vera gel and sodium alginate (AGSA), was applied directly on cotton using manual screen-printing method to gaining best result, using mixture of thickener (20 gm aloe vera and 2.5 gm sodium alginate), cotton printed fabrics had good characteristics include washing fastness, high color yield, softness and hand feeling properties, with medium viscosity and washing easily removed the extra chemicals. Aloe vera can be applied to cotton as a new thickening agent in reactive printing, achieving increased thickening efficiency as well as better depth and stability properties for printed samples, printing cotton samples with Aloe vera gel exhibited excellent results (wash and lightfastness) when using 4gm reactive dye concentration. Aloe vera gel as thickener with direct dye on cotton, aloe vera thickener was successfully applied on cotton fabrics with 3gm direct dye. When using after treatment with 10% vinegar for 5 minutes gave best result. Aloe vera gel as thickener with pigment on cotton. In printing with pigments, the use of a low-solids thickener is required, as it remains with the fabric after printing. zero-solids emulsion thickeners become quite prohibited in recent years owing to problems such as a better comfort property in terms of vapor permeability. Poor sharpness of the printed sample and less color yield were observed when only Aloe Vera gel was used aPs thickener, followed by an improvement in color yield with Sodium Alginate addition, aloe vera gel as thickener for printing of cotton fabric with pigment, in combination with sodium alginate, to enhance the properties of the printed fabric (sharpness, color yield, overall fastness properties, softness, and water vapor transmission) which are dependent on the percentage of Aloe vera gel in the thickener combination, the concentration of printing auxiliaries, and the curing conditions. Optimum printing properties were achieved by using a printing paste containing 80% Aloe vera 20% sodium alginate (700 g/kg), pigment (50 g /kg), binder (145 g /kg), fixer (10g/kg), and ammonium sulfate (5 g /kg), followed by drying at 85 ” C for 5 min and curing at 150 ” C for 3 mi. Emission of volatile organic compounds (VOCs) into the atmosphere during the drying and curing stage, flammability or explosion risk, wasteful use of energy, and ever-increasing cost. because aloe vera gel contains a very low solids content, allowing most of its constituents to be evaporated during curing treatment. For the same reason, a sample printed with higher aloe vera shows Aloe vera gel as thickener with natural dyes on cotton, adding aloe vera into printing paste as a part of the thickener when printing with natural dyes and examine its effect on the printed fabric and on the fabric sew-ability. Printing pastes as expected lower the fabrics sew-ability, due to the additional printed film over the fabric surface, that the needle must penetrate through. knitted and woven cotton fabrics was printed with two different thickening agents (sodium alginate and acrylic thickener) with natural dyes turmeric, annatto and Saffron. aloe vera was added to sodium alginate to enhance fabric properties. With curcumin paste aloe vera showed best results in fastness properties specially rubbing wet properties and sew-ability. Antimicrobial Finishing Methods, Coating, Exhaust, Pad-dry-cure, Spray & foam techniques, Synthesize Zinc Nano particles stabilization, or Fiber spinning method. Pad dry method was the best way to give greater antibacterial properties which also made the fabric soft. The antimicrobial finishes are generally applied by following means to the textile substrate: Absorption or Surface Treatment, Chemical Bonding, Micro-encapsulation. The microencapsulation of essential oils and its application in textile allows the gathering of various functions to substrates, imparting them antimicrobial properties, UV protection, and others. The microencapsulation involving essential oils applied to textile substrates enhances the lifespan of this kind of product, avoiding rapid evaporation of it. The release might happen due to the sensibility of the wall to the pH, heat, mechanical pressure, humidity, and other factors. The microencapsulation guarantees the protection of the active principle, as well as its controlled release, hence the great interest of its application in textile materials, microencapsulation of Aloe Vera with cornstarch using the simple coacervation technique on nonwoven cotton fabric using butane tetracarboxylic acid (BTCA) as a binding agent. FTIR was used to prove the interaction between nonwoven and microcapsule. Cornstarch was used as encapsulating agent and Aloe vera as active principle. For the formation of the coacervate, a mechanical stirrer was used. The analytical agents used were Acetic Acid (AcOH) 10% v/v, Sodium Hydroxide (NaOH) 1 mol/L for pH correction. Glutaraldehyde (C5H8O2) 10% (v/v) was used to stiffen the walls of the microcapsules, using the pad-dry-cure method. the nonwoven samples were immersed in the bath for 1 min containing 30 g/L of microcapsules dispersed in aqueous solution, 75 g/L of butane tetracarboxylic acid (BTCA) (binding agent), and 45 g/L of sodium hypophosphate (Na PO2H2) (catalyst) note a polydisperse distribution, with irregular shape and sizes varying from 3 ?m to 50 ?m, Aloe vera can be used as a natural dye and mordanting agent, and gel used instead of salt in a reactive dyeing process, as well. Many attempts to use aloe vera as thickening agent. Aloe vera gel can be used in combination with sodium alginate as a thickener to suit printing cotton fabric with reactive dyes. Aloe gel has a potential of changing the property of disperse dye to have good interaction with cotton.
