A large amount of coarse wool, practically unserviceable for textile use, is generated in Europe from sheep shearing and butchery. Such a byproduct is either dumped, burned, or sent to landfill. Following the European Commission regulations on animal byproduct control, unserviceable raw wool is classified as a category 3 special waste materials. The collection, storage, transport, treatment, use, and disposal of such unserviceable raw wool are subject to European Union regulations because of a potential risk to human and animal health. This study aims at converting the waste wool into nitrogen fertilizers at a commercial scale for grassland management and cultivation purposes. The chemical transformation of waste wool in to fertilizer is based on a green economically sustainable hydrolysis treatment using superheated water. The experiments were carried out in a semi-industrial reactor feeding superheated water. The wool/superheated water system was maintained for different reaction times. The optimal conditions for this treatment were as follows: 170 °C for 60 min with a solid to liquor ratio (MLR) close to 1. The hydrolyzed product was analyzed using amino acid analysis and molecular weight distribution. Both the amino acid and molecular weight distribution analysis revealed that the wool was completely degraded and the hydrolyzed product contains a low molecular weight proteins and amino acids. Several hydrolyzed product obtained at different conditions were tested for germination which showed a germination index higher than 100% without collateral phytotoxicity. The presence of amino acids, primary nutrients, and micronutrients in wool hydrolyzates, along with a concentration of heavy metals below the standard limit, confirm the possibility of using wool hydrolyzates as a nitrogen based ecologically sound fertilizer.
A large amount of wool produced in the EU region is coarse and of low quality. The limited or nonutilization of such coarse wool leads to landfilling causing environmental pollution. In this paper, we studied the properties of keratin hydrolyzate, produced by a sustainable hydrolysis process, to be used as a foaming agent in foam dyeing of cotton and wool fabrics. This is a preliminary step on the way to find possible applications which overcome the environmental problem of wool waste and byproducts. We report for the first time the use of keratin hydrolyzate as a foaming auxiliary in the textile dyeing process. The surface tension, molecular weight, foam stability, blow ratio, and bubble size of keratin hydrolyzate in aqueous solutions with and without dyeing auxiliaries were determined. The dyeing influential parameter such as wet pickup was studied to identify their effect on dye fixation and color strength. The foam dyeing was compared with conventional cold-pad batch and pad-steam processes for cotton and wool, respectively. In the investigated variant, keratin hydrolyzate shows a reduction in surface tension, good foam stability along with dyeing auxiliaries, a blow ratio of about 10:1, and 0.02–0.1 mm diameter bubble sizes. These results make possible its application as a foaming agent. Cotton and wool fabrics were dyed using reactive and acid dyes respectively, on a horizontal padding mangle. In both cases, hydrolyzed keratin acts as a carrier for dye molecules and the mechanism of dyeing depends on the respective pH of the dye solution, keratin, and fiber. Foam dyeing of cotton resulted in comparable color strength, while wool shows higher color strength when compared with conventional dyeing processes. Washing and rubbing fastness of cotton and wool foam dyed fabrics are similar to the respective conventional dyed fabrics. The combinations of sustainable keratin hydrolyzate production and its use as an eco-friendly, biodegradable foaming agent in less add on foam dyeing technology resulted not only in saving of large amounts of water and energy but also will be helpful in minimizing a load on effluent and the environment.
Conventional wool dyeing methods are based on long times at high temperatures. These are energy intensive and can even damage the fibers, thus changing the desired fiber characteristics. In this work, enzyme pretreatment in combination with lower temperatures was used to reach exhaustion values comparable to those obtained with the standard procedure at 98°C. Kinetic runs carried out on wool yarn at different temperatures confirmed the possibility of obtaining more than 90% of bath exhaustion by dyeing at 85°C due to the pretreatment with a proteolytic enzyme. At the same temperature, without enzymatic pretreatment, just 77% of bath exhaustion can be reached. The enzyme action on the dyeing kinetics was investigated through calculation of dye absorption rate constants according to the diffusion‐limited kinetic model proposed by Chrastil. Dynamometric measurements on the yarn dyed at 98°C showed a 25% loss of tensile strength and 50% loss of elongation, while at lower temperature the values were better even after enzyme pretreatment, in agreement with the results of scanning electron microscopy analysis. A temperature of 85°C with enzyme pretreatment was found to be optimal taking into account satisfactory washing, perspiration and light fastness values.
Abstract:© Versita Sp. z o.o.
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