Kinetics of leather dyeing pretreated with enzymes: Role of acid protease (original) (raw)
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Ecofriendly Dyeing Process with Enzymes
The International Conference on Advanced Materials and Systems, 2016
Biological degradation of many dyes is difficult. Therefore dyeing baths give high pollution load to waste water. In this work, the use of enzyme in the dyeing of leather has been studied with the aim to improve the exhaustion of dye and to reduce pollution load of dyeing waste bath. For this purpose, chromium-tanned leather were treated with different ratio enzyme after the neutralization process. Then dyeing has been carried out. The effect of bacterial protease on colour properties of leathers was investigated. Also the change of the amount of COD load in the waste dye baths and leather physical properties were investigated. The obtained test and analysis results show that when the enzyme was used in the dyeing process, the COD load of waste dye baths was reduced.
International Journal of Innovation and Applied Studies, 2017
Surface modification of wool/nylon blended fabric was carried out with protease enzyme to improve their dyeabilities to natural dyes. Cutch (Acacia Catechu) was selected and used in this study. The effect of enzyme concentration on the dye uptake (K/S) was studied at fixed treatment conditions: pH, temperature and treatment time. The obtained results of K/S were compared to the corresponding values obtained for the control samples which were dyed without enzymatic pretreatment. Treatment with protease was found to increase the absorption capacity of both wool and nylon fibers to the natural dye leading to higher K/S compared to untreated samples. The dyeing parameters were also studied including, dyeing pH, temperature, time and mordant concentration along with concentration of dispersing agent. The colour strength was observed to increase by increasing the pH of dye bath, temperature and concentration of dispersing agent, which may be attributed to increasing dye solubility and as ...
Enzyme-aided wool dyeing with a neutral protease
2010
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 981C. Kinetic runs carried out on wool yarn at different temperatures confirmed the possibility of obtaining more than 90% of bath exhaustion by dyeing at 851C 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 981C 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 851C with enzyme pretreatment was found to be optimal taking into account satisfactory washing, perspiration and light fastness values.
Wet Blue Enzymatic Treatment and Its Effect on Leather Properties and Post-Tanning Processes
Materials
Due to their variety, specific activity, and mild reaction conditions, enzymes have a wide application in beam house processes such as soaking, dehairing, bating, and de-greasing. Recently, due to improvements in biotechnology, re-bating after chroming has received increased attention. The aim of this work was to investigate the application of enzyme preparation in the re-bating process and its effect on the semifinished and finished product, as well as its influence on post-tanning operations. The enzymatic treatment of chromed semifinished leather (wet blue) led to a higher shrinkage temperature (1–6 °C), greater water vapour absorption (0.3–5.5%), better chromium compounds exhaustion during re-chroming (4–21%), and better dye penetration. Moreover, collagen was affected during the enzymatic process; the results showed a greater concentration influence in the operation compared to the process time. On the other hand, no effect on the physical and mechanical properties and fat-liqu...
Enzyme-aided wool dyeing with a neutral protease at reduced temperatures
Engineering in Life Sciences, 2010
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 981C. Kinetic runs carried out on wool yarn at different temperatures confirmed the possibility of obtaining more than 90% of bath exhaustion by dyeing at 851C 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 981C 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 851C with enzyme pretreatment was found to be optimal taking into account satisfactory washing, perspiration and light fastness values.
Desalination, 2011
Leather dyes are important chemical pollutants of industrial origin. The society demand for colour-free waste discharge to receiving waters has made decolourisation of industrial wastes a top priority. Due to their complex chemical structures, the decolourisation of these wastes is a challenging task. In this study, the decolourisation and degradation efficiency of six leather dyes by enzymatic and electrochemical treatments were studied. In the presence of salts, all dyes were totally decolourised by electrochemical treatment in 4 h. Though it has showed appreciable ability of enzymatic degradation, it was observed that the salts present in tannery effluents cause inhibition problems that significantly affected the dye degradation. In addition, enzymatic and electrochemical treatments with a mixture of the six dyes were carried out. Once again, the electrochemical treatment shows better results and after 4 h the obtained decolourisation was total which is squared with a complete total organic carbon (TOC) reduction. Besides, the degradation of this mixture was carried out successfully in a continuous electrochemical bubble reactor. Therefore, the results provide fundamental knowledge for the treatment of a leather wastewater stream.
Optimization of Leather Dyeing using Natural Dye Extract
2018
Consideration of environmentally friendly manufacturing process and product become indispensable issue due to increased environmental and health consciousness. In this regard many nations in the globe have stringent rules and regulations for industrial manufacturing and products to be safe both for environment and human health. Leather is animal skin widely used for footwear, garment, household and technical products. Leather products are colored with synthetic dyes of which, their processing have impact on environment and human health. Hence, the use of nonallergic and nontoxic natural dyes for leather coloration is a matter of significant importance as an option of dye source. The extract from the plant botanically called Osyris Quadripartita and Qerete locally used traditionally for leather dyeing in Ethiopia and other East Africa countries. In this research work, extracting and dyeing conditions were optimized to widen the application of the Osyris Quadripartita plant as a natur...
Studies on the influence of bacterial collagenase in leather dyeing
Dyes and Pigments, 2008
Collagenase enzymes are nontoxic and eco-friendly biocatalysts. Dyeing is an important process in the leather industry, which employs many synthetic colorants. Many good dyes suffer from incomplete exhaustion and this causes concern, as the biotreatability of the unexhausted dyes in effluent is normally difficult. Hence in the present study, an attempt has been made to improve the exhaustion of dyes by using bacterial collagenase enzymes as biocatalysts. The effect of process parameters of enzymatic treatment such as pH, temperature and duration on the exhaustion of the dye, levelness of dyeing, shade brightness, dye penetration and color intensity have been studied and the conditions are optimized. Uptake of dye as high as 99% has been observed by the treatment of collagenase. The change in shades due to enzymatic treatment has been quantified by reflectance measurements and compared with the visual assessment data. Scanning electron microscopy analysis showed a well opened-up fibre matrix for the collagenase treated leather. The strength properties are not significantly altered and the bulk properties like softness have been found to be improved by the use of collagenase.
Use of Enzymes and Chitosan Biopolymer in Wool Dyeing
Fibres and Textiles in Eastern Europe
The importance of bio-processes and mild chemical so-called ‘soft chemistry’ processes have been increasing of late. Especially for expensive and fashionable material such as wool and silk, the compatibility with the environment and protecting these fibres’ natural properties during their treatments have been investigated. In this study, we used proteases of different origins to treat wool-woven fabric. Proteolytic treatments were carried out with various commercial protease preparations such as Perizym AFW, Alcalase 2.5L, Savinase 16L and Papain. After proteolytic treatments, the samples were evaluated with regard to the loss of tensile strength, weight loss, degree of whiteness and alkali solubility. The samples were then dyed with different classes of dyestuffs such as reactive dyes, levelling acid, milling acid and metal complex dyestuffs. The effects of these proteolytic treatments on colour strength and various fastness values were evaluated. Moreover, some samples treated wit...