Leather Technology

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    Extraction Of Glycosaminoglycan’s from Raw Hides Trimming Waste by Using Papain Enzyme
    (Addis Ababa University, 2023-01) Woldeamanuel Wondaferash; Shegaw Ahmed (PhD)
    Glycosaminoglycans are the most plentiful type of organic active polysaccharides mainly found in animals. Chondroitin sulfate (CS) are one of the classes of glayconsaminoglaycans that can commonly use in pharmaceutical, cosmetics and beverage industries as well as in treatment of arthritis and eye diseases. Therefore, taking out of Glayconsaminoglaycans from cow hide trimming waste by papain enzyme is necessary. In these process temperature, time, enzyme and PH are variables that can affect the result of Glayconsaminoglaycs. The best result of data was taken at pH of 6.7, enzymes concentration 0.6 %, temperature of 68OC and hydrolysis time 3 hours. The extracted Glayconsaminoglaycans were 0.5 % and its composition were 62.7% carbohydrates and16.4 % proteins, moisture content 13.1%, and ash content 7.8 %. The experiment analysis was analyzed by using UV spectroscopy and characterize by FTIR and NMR analysis.
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    Standardization of Post Tanning for Waterless Chrome Tanning: Upper Leather
    (Addis Ababa University, 2021-11) Bisrat, Tesfamichael; Rao, Rajahava (PhD); Shegaw, Ahmed (PhD)
    Waterless Chrome Tanning Technology (WCTT) is a new technology in which the chrome tanning part of leather processing is carried out without water and with simple chemicals that insure excellent absorption of chromium by the hide thus avoiding the chrome waste water. but to bring the consumers (tanneries) to use this new technology in large scale we need to remove their fear and build their confidence in this new technology; one way of doing this is to have or show them a standardized process (post tanning). This research focuses on standardizing the post tanning operation for WCTT upper leather; different recipes were experimented with trial and error, but first to find if there is even a need to have a new post tanning recipe for the WCTT both conventional chrome tanned and WCTT were processed with the same conventional post tanning recipe, after that both the conventional chrome tanned and WCTT final crust leather were evaluated with organoleptic method and physical testing. The WCTT final crust made with conventional post tanning shows some lower organoleptic values, so to correct this, different post tanning trials were done, some of the trials were avoiding re chroming and checking the chrome oxide content, adjusting the neutralization by using different percentages of sodium bicarbonate and checking the pH of the leather, using different re tanning recipes, using neutralizing syntan in neutralization stage, on the dye part different percentage of dye is used and the best percentage is chosen based on the organoleptic result of the final leather and the final liquor color; also a trial of adding the dye in two batches to shorten the dye penetration time. The final leathers were assessed for fullness, roundness, grain smoothness, looseness, grain tightness, colour uniformity. Organoleptic properties or Functional properties of leathers in a scale of 0 – 10 points were rated by three experienced CLRI staff and average values were taken. Higher values indicate better properties. The physical properties such as tensile strength, water vapour permeability, water penetration, colour fastness, elongation at break were also done.
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    Studies on Cleaner Leather Process of Ammonia Free Deliming, Bating and Degreasing Simultaneously
    (Addis Ababa University, 2021) Tamiru, Alemayehu; Kanagaraj, J. (PhD)
    The study presents the design of cleaner leather process of ammonia free deliming, bating and degreasing to facilitate the production of leather. Ammonia salt bating and solvent degreasing are well known and adopted globally. Development of green chemicals and short coming of ammonium salts and organic degreasing solvent system of processes calls for a need for the development of cleaner leather process of bating and degreasing. Hence this research work focused on, the development of cleaner leather process of combining bating and degreasing in single bath using commercially available and cheap enzymes as an alternative bating and degreasing process. Bating and degreasing in single bath system gives thin wet white pelts with high thumb impression. Among the selected enzymes and design process evaluated leathers obtained by alkaline bating and degreasing (peltec-BB and peltec-BC-E-F respectively) with in 1hr process were observed to be stronger, better general appearance and good run properties. In contrast acid bating and degreasing after pickling with 1hr process resulted poor organoleptic properties and less run properties. Physical testing and organoleptic properties of the matched pair leathers of the alkaline bating and degreasing system simultaneously were comparable to that of conventional bating and degreasing system of leather process. Most important is that it would not produce ammonia, reduce chemical consumption and produce very clean and wet white pelts, therefore alkaline bating and degreasing enzymatically in single bath good process for the manufacture of glove leather.
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    Improving Efficiency of Vegetable Tannin from Wattle Bark and Its Comparison with Different Conventional Extraction Methods
    (Addis Ababa University, 2021-11) Fanuel, Tadesse; Shegaw, Ahmed (PhD)
    Conventional extraction processes affect our environment and consume a huge amount of solvent and these problems have stimulated considerable interest in the development of environmentally friendly extraction methods, which are prepared by enzyme and microwave pre-treatment methods. The objective of this research is to improve the extraction efficiency of vegetable tannin and compare it to other extraction methods. Extraction pre-treated with Microwave pre-treated was found to be easier and time effective than other extraction. But the percent yield relative to enzyme pre-treated extraction methods is small. The extraction of wattle bark was also performed by enzyme pre-treatment at 48°C for 60 minutes using 2% of concentration. Enzyme pre-treatment extraction method is best method among all the extraction methods which been 64.585 % yield obtained which is (30.52%) much higher than the conventional extraction methods. The enzyme pre-treated wattle powder was characterized using dynamic light scattering (DLS) and a spectrophotometer. DLS determined the average particle size to be 167.0 nm, with a poly disparity index of 0.0369. Color the extract was measured using a Minolta CR400 Chroma meter. The spectrophotometer result shows that a higher breakdown of the desired product and increased extraction efficiency that the total phenolic contents in 2% of the enzyme were the highest (78.1669) mg GAE/g dry extract. The total phenolic content of the control was 55.6286, which was much lower than the enzymatic pre-treatment method. The tannins were applied to leather after characterizing the tannin extract. it is observed that the strength characteristics like tensile strength, % of elongation at break, tear load (double edge tear), ball burst (distention at a crack and burst, and load at burst) of the crust leather produced by wattle powder as re-tanning material is found to be good when compared to the conventional re-tanning process. Finally, study organoleptic properties in comparison to locally used commercial tannins were studied and a good result was achieved.
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    Production of Acoustic Material from Chrome Shaving Wastes and its Evaluation as Soundproofing
    (Addis Ababa University, 2021-12) Tesfay, Gebregewergs; Shegaw, Ahmed (PhD)
    In tannery sectors, chrome shaving is one of the most hazardous solid wastes that have a serious impact on public health and the environment when discharged to the land without treatment. Utilization of large amount of chrome shaving waste is very critical to reduce environmental pollution effect. Hence, this research is focused on the production of acoustic material from chrome shaving wastes combining with animal fiber so as to reduce environmental problems of chrome shaving waste and to get value added products which is used as sound absorbing material in building applications. The acoustic material were prepared from chrome shaving waste and animal fiber using hydraulic pressing machine at the temperature of 150oc and pressure of 50bar. Styrene butadiene rubber was used for blending purpose and animal fiber (sheep wool fiber) was chosen as reinforcement due to its excellent sound absorbing capability and it has good fibrous content in nature. The effect of addition of animal fiber to the final product were assessed by varying ratios of concentrations in preparing of acoustic materials. The density and thickness of the acoustic materials were determined using appropriate measurements. The physical testing of the prepared materials were measured by controlling the temperature at 23.2oc and with relative humidity of 45.7%. The acoustic material (30% Cr & 70% W) were found as good material in the results of physical properties which have better tensile strength, elongation at break and tear strength when compared to the other acoustic materials. The sound absorption of the prepared acoustic material were measured using impedance tube with two microphones transfer function method. The results suggested that the acoustic material of (30% Cr & 70% W) and the acoustic material of (70% Cr & 30% W) have better sound absorbance in the lower and higher frequencies, which can be used as sound absorbing panel at home, class room, auditorium and music studio by providing good hearing ability thus making environmental friendly value added products from wastes.
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    Characterization and Optimization of Chrome Free Tanning System Using Combination of Chestnut and Tetrakis Hydroxymethyl Phosphonium Sulfate
    (Addis Ababa University, 2021-09) Haftom, Girmay; Berhanu, Assefa (PhD)
    Currently, chrome tanning accounts for more than 90% of global leather manufacturing. This tanning system result in significant material loss and considerable environmental concerns. In the present work, chrome free combination tanning system using a combination tanning system based on Chestnut and THPS is presented. The processing method for Experimental tanning trials were carried out with different percentages of Chestnut as a tannage followed by varying percentages of THPS as a re-tannage for process optimization. The leathers obtained were characterized for their physical strength characteristics, comfort & organoleptic properties, scanning electron microscopic analysis, reflectance measurements and environmental characteristics. The Chestnut-THPS leathers tanned using 20% chestnut followed by 2% THPS resulted in shrinkage temperature of 95OC. The hydrothermal stability of the combination has been found better than the Chestnut alone and THPS alone tanned leathers, respectively. The strength properties and comfort properties of leathers obtained are on par with or better than the control chrome, Chestnut alone and THPS alone tanned leathers. The organoleptic properties of the experimental crust leathers exhibit good grain smoothness, fullness, grain tightness, general appearance compared to control chrome tanned crust leathers. Environmental impact assessment shows the combination tanning system results a significant reduction in TS, TDS, TSS and BOD in the waste water when compared to that of control tanning system. The study presented in this paper established the use of Chestnut and THPS combination tanning system as an effective alternative cleaner tanning methodology.
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    Extraction and Optimization of Natural Protein (Keratin) from Waste Chicken Feather for the Development of Anti-Ageing Cream
    (Addis Ababa University, 2017-10) Tewodors, Abebe; Karthikeyan, R. (PhD)
    Treatment and conversion of by-products into value added products would help not only to strengthen the economy of a country but also to protect the environment from pollution and to improve the socio-economic status of the people by creating employment. Keratin is abundantly available as a byproduct from poultry, slaughterhouse, tanning and fur processing industry. Chicken feathers, cattle and buffalo horns, tannery hair are the abundantly available sources of keratin which could be successfully converted into high value products on a large scale. In the present investigation has been made to extract valuable protein from chicken feathers and to study change in temperature, time and chemical concentration during thermo-chemical treatment thereby optimize the extraction conditions for the development of anti-ageing cream. Sodium hydroxide is used to digest the raw chicken feathers. Once the feathers are dissolved, hydrochloric acid solution is added to the solution for the precipitation of protein. The precipitated protein is washed with water several times and the protein was subjected to separation by centrifugation and freeze-drying. The effect of different parameters, such as extraction temperature, time, and NaOH concentration was studied in relation to extraction yield of keratin protein. The percentage keratin yield was found to be 23 to 82% in different extraction conditions. The extracted keratin protein was further analyzed by biuret test, FT-IR, XRD and TGA. Biuret test, FT-IR studies have been done to confirm the protein nature. XRD and TGA were used to know physical characteristics of the regenerated protein from chicken feather. A general factorial design was applied to both extraction processes using Design Expert software and linear regression model was obtained growing the individual effect of extraction temperature, time, and NaOH concentration and their interaction in the entire extraction process. The optimum condition for the extraction of keratin protein from chicken feathers was found to be 5g feather, 0.75 N NaOH and 45 minutes reaction time at 60oC temperature. The keratin extraction developed by the optimized thermo-chemical conditions was used to produce anti-aging cream by using ingredients which include emulsifier, emollient, preservatives and surfactant.
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    High Performance Glove Leather from Goat Skin: Role of Physico-Chemical Properties
    (Addis Ababa University, 2014-09) Tarekegn, Jida; ChandraBabu, N.K. (PhD); Aravindhan, R. (PhD)
    The chemical and physical characteristics of the goat skins are essential to make glove leathers. The characteristic of skin can be analyzed by using Scanning Electron Microscope (SEM), light microscope and studying histological structure of the skin as well as through various chemical characteristics. The fiber opening operation as well as the post tanning auxiliaries like syntans and fatliquors are known to significantly influence the properties of glove leathers. The right choice of lyotropic agents, fatliquors and syntans are critical to obtain the leathers with good gloving property. Hence, in this thesis an attempt has been made to study the physico-chemical properties of the skin and to study systematically the influence of various lyotropic agents, fatliqours and syntans on the gloving properties of leather made from goat skins. Care was taken to ensure that the properties of gloving leathers viz.run, softness, strength properties and other subjective properties like smoothness and stretch based on the physico-chemical properties of the skin were obtained.
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    Studies on Effect of Different Pigment and Binder Combinations on Surface Property of Finished Leather
    (Addis Ababa University, 2014-09) Mishamo, Wakaso; Dhathathreyan, Aruna (PhD); Kanth, Swarna V. (PhD)
    The present work attempts to analyze the surface and physical properties of leathers finished with various combinations of binders and pigments by keeping other auxiliaries constant. The contact angles of liquid drops resting on the leather surface have been used to evaluate surface energy, acidity, basicity components of the surface energy, polarity and work of adhesion. Contact angle values have been measured for chrome tanned and conventionally re-tanned crust and finished leather made by varying pigment and binder combinations. The wettability of finished leather has been correlated with the contact angle values: the higher the contact angle value the less wetting is observed. Complete wetting can be obtained when the contact angle value is zero i.e. the drop of liquid spread spontaneously on the surface and partial wetting is obtained when the contact angle value is in between 00 and 90o. Acrylic binders with different film forming properties, protein, polyurethane and butadiene binders have been combined to prepare different finish formulations. Pigment to binder ratio for acrylic system and acrylic with polyurethane binder system have been optimized from the information obtained from contact angle values which have direct relation to degree of wetting. And the results have been correlated with wet and dry rub fastness, finish adhesion, vamp flexing value, water vapour permeability and water proofness. It has been observed that when the surface of leather is coated with acrylic binder the contact angle value due to polar solvents(water) , non polar solvents(hexadecane) and moderately polar( DMSO) and methyl iodide show that as the thickness of coating increases, the contact angle value decreases for the base coat and sharply increases when top coat is applied. Top coats have the ability to increase the contact angle and they improve the performance properties of leather such as water resistance, fastness, finish adhesion etc. Cationic and anionic finishing formulations have been compared to study their effect in modifying the surface of finished leather based on contact angle values, wet and dry fastness to circular rubbing and water resistance. It has been observed that leathers finished using anionic finishing technique shows better wet rub fastness and water resistance effect compared to cationic finishing technique.
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    Quebracho-Zinc Sulphate Combination as Chrome-Free Tanning Agent
    (Addis Ababa University, 2014-09) Melkamu, Kassahun; Chandrasekaran, B. (PhD)
    Leather has remained a unique material for a long time. visco-elasticity and pore size distributions are two important properties of leather that have rendered it a unique material. The ability to breathe and readjust to volume fluctuations of the foot has made leather a unique material of choice in footwear industry. The environmental pollution problems pressures on chromium and forced the leather industry to find the possible alternatives. In the present study, a combination tanning system based on a quebracho –zinc tannage for the production of versatile leathers as a cleaner alternative is presented. A combination tanning system based on qubracho and zinc sulfate. (quebracho-Zn) leathers tanned using 8% quebracho followed by 6% ZnSO4.7H2O; resulted in shrinkage temperature is 87°C. The uptake of quebracho-zinc combination tanning system with quebracho (8%) and zinc (6% ZnSO4.7H2O) has been found to be better than the tanning system of quebracho and zinc tanning systems. The combination tanning system provides significant reduction in the discharge of COD, BOD5 and TDS in the wastewater. Quebracho-Zn combination tanning system resulted in leathers with good hygienic, bulk and strength properties. The work presented in this paper established the use of quebracho and zinc combination tanning system as an effective alternative cleaner tanning technology.
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    Approach Towards High Performance Water Vapour Permeability Upper Leather from Goat Skin
    (Addis Ababa University, 2014-09) Mekonnen, Bekele; Muralidharan, B (PhD); Das, B.N. (PhD); John, Sundar (Mr.)
    The mechanism of increasing WVP Goat upper leather, the processes have been developed. These process developed during the project were, increased percentage of bating enzyme during bating process, increased the duration time of liming process, avoided the qubracho powder and acrylic syntan during retanning process, decreasing of synthetic fat liquor and instead used semi synthetic fat liquor, increased the percentage of degreaser during degreasing process, after wet blue for 2hrs treated the leather with 1% of urea and acetic acid. For each process, the physical properties such as WVP, tensile strength, percentage elongation at break, tear strength and grain crack were carried out. The result obtained from each process at crust and finished listed in chapter 4 in table form. The experiments carried out for both control and experiments for all experiments.
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    Combination Tanning Based on Tara and Sodium Metasilicate a New Chrome Free Tanning System
    (Addis Ababa University, 2014-09) Getaneh, Andualem; Madhan, B. (PhD)
    Chrome is the well-established tanning system adopted globally. Consumer awareness and short coming of chrome tanning system calls for a need for the development of chrome free tanning, Hence this research work is focused on, the development of silica and vegetable tanning agent (Tara) combination tanning system as an alternative to chrome tanning. This tanning system eliminates the use of chromium in tanning process thereby environmental impact of chromium can be avoided. Silica remains in solution at a narrow pH range and hence in order to keep the silica in sol at pH of about 3, silica tanning salt was prepared by masking with salts viz., sodium citrate and sodium tartrate. The combination tanning based on silica and tara were optimised for the amount of tara, order of addition and masking salt used for the preparation of silica tanning agent. The order of addition of silica and tara, amount of tara and also the type of masking agent had a significant influence on the shrinkage temperature, physical strength and organoleptic properties of the leathers produced. Tanning system with tara followed masked silica gives resulted in wet white leathers with shrinkage temperature of 80oc. Among the combination system evaluated, leathers obtained by vegetable (Tara) pretannage followed by retannage with masked sodium metasilicate were observed to be stronger, fuller and better general appearance with the durable characteristics. In contrast, pre-tanning with masked sodium metasilicate resulted in leathers with poor organoleptic properties and less hydrothermal stability. In general the characteristics of the leathers obtained by tara- silica combination system provides leathers with good organoleptic properties and comparable physical strength for upper leathers. Physical testing and organoleptic properties of the matched pair leathers of the tara-silica combination tanning system were comparable to that of chrome tanned control leathers. Skins stabilized with tara - silica combination tanning could be adapted to shaving readily; most important is that it would not produce wastes containing chromium means it is zero chrome discharge because chromium is not used in this tanning system. Therefore the tara-silica combination tanning is a good tanning system for the manufacture of upper leathers. The tara-silica combination tanning system also resulted in leathers with good buffeability and hence the leather made from this tanning system is also suitable for the manufacture of suede leathers especially for upper. The cost of the new system is higher but can be compensated with the environmental benefits by eliminating chrome in leather manufacture.
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    Improvement of Colour Uniformity During Dyeing Operation: The Case of Dress Gloving Leather
    (Addis Ababa University, 2018-06-17) Wondwossen, Mamuye; Berhanu, Assefa (PhD); Aravindhan, R. (PhD); Jawahar, Malathy (Mrs.)
    In leather industry, the tanner produces a production lot with large number of leather samples to match a colour provided by a client. However, even when the leathers are dyed with the same colorants under well monitored conditions may show some colour non-uniformity. This is highly challenging today for leather manufacturers, especially glove producers to sort colour of leathers consistently. The present study is focused on identifying the factors of colour variation during dyeing operation and reducing colour non-uniformity by managing the factors with welldesigned dyeing recipe. Dyeing properties of the dyestuffs was investigated, by choosing two commercially available dye stuffs. Factors of colour non-uniformity are identified by conducting dye trials on possible causes of colour non-uniformity with four different well-designed dyeing recipes. When concentration of dyestuff, substance of skin or length of dyeing float are varied individually keeping others factors the same, a perceivable total colour difference (∆E*≥0.5) is observed. Controlling and monitoring of colour non-uniformity is analyzed by conducting dye trials using four different well-designed dyeing recipes viz. reverse dyeing recipe, regular dyeing recipe, the multiple stage dyeing recipe and regular dyeing recipe with dye levelling agent. The total colour difference (∆E*) values obtained using multiple stage dyeing recipe was smallest as compared to the other three recipes by varying all possible factors of colour non-uniformity individually. From these observations, multiple stage dyeing recipe was the best alternative way to manage colour non-uniformity.
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    Extraction and Characterization of Elastin from Raw Hide Trimmings using Autoclave Extraction Technology
    (Addis Ababa University, 2018-06) Zerihun, Yoseph; Berhanu, Assefa (PhD)
    During leather processing, raw skins/hides are trimmed and thrown as wastes and accounting for pollution load in leather industry. Elastin is a fibrous protein with multifaceted applications in biomedical field due to its intrinsic biological annotations viz elasticity and cell interactions, the extraction process is challenging task due to their cell interactive properties, the application is versatile and the price is in current international market is highly expensive. In this context, leather solid wastes specifically raw hide trimmings have been found out in the research as the potential source of raw material for elastin extraction. In this research, the raw Hide Trimming elastin content was estimated between in the range of 122 mAUmin and 97 mAUmin using the combination of FPLC, UV-Spectroscopy, SDS-PAGE protein scientific characterization techniques. The Elastin was extracted from leather waste through autoclaving technology, the method yield was found to be 90%. In addition, the biocompatibility study confirms that there is no toxic nature of extracted elastin for biological application. This implies that the selected extraction process was effective and efficient. The physical characterization using DSC result indicates that the melting peak of elastin was -0.5420 watt/g at 103.23 C, elastin showed very high denaturation temperature of 275.82 o C and TGA studies confirm that elastin have six mass loss degradation steps. The chemical characterization result using o C Solid state NMR and FTIR that elastin shows random coil, α-helix and β-strand secondary structure. Moreover, the FTIR confirm that amide A, I, II, III, IV, V, VI, and VII functional group existed in the elastin fiber. The biological characterization using amino acid analysis result show that the amino acid composition chain of the product have high amount of glycine, non-polar amino acid, low amount of acidic amino acids, low amount of hydroxyl amino acid and there is no hydroxylsine, tryptophan and Cysteine amino acids in the amino acid composition of the protein fiber. The little variations were the existence of high amount of basic amino acids in the protein amino acid composition due to the presence of collagen residues. Finally, the biocompatibility study shows that there is no toxicity nature of the extracted elastin fiber for human keratinocyte cells culture. There result is scientifically justified and confirmed that the raw hide trimmings extracted elastin makes feasible for biological and biomedical applications.
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    Manufacture of High-Performance Sheep Upper Leather From Low Quality Sheep Skins in Selection Through Process Upgradation and Optimization
    (Addis Ababa University, 2018-06-27) Wondimu, Wolde; Abubeker, Yimam (PhD); Aravindhan, R. (PhD)
    The quality of a raw material for any manufacturing industry or firm is one of the decisive factors controlling its productivity and profitability. Leather processing industries are no exceptions to this fact. The decline of quality raw material supply for the leather processing industries is a great challenge to be competent and survive in the industry these days. The quality of the raw material is largely affected by different factors. The problems leading to lower selection of raw skins or semi-processed skins in industry are categorized as ante-mortem and post-mortem defects. Especially the ante-mortem defect caused by ecto-parasite attack on the skins surface is one of the major problems for downgraded selection of sheep and goat skins. In this research work, an attempt has been made to upgrade poor and reject wet blue leathers due to mange disease damage or “Ekeke” on sheep skin. The problem of lower quality selection of skins could be improved and upgraded into better quality shoe upper leather by working on suitable leather processing techniques for covering the defects of mange damaged skins in wet-finishing and finishing by upgradation and optimization. In wet- finishing process, filler waxes and pigments combination were employed for upgradation. This has resulted in improved coverage of defects on dyed crust leathers. Physical strength tests and organoleptic property assessments performed on the treated leathers are found to be good. The optimized process of dyed crust leather is taken further for finishing, where five finishing methods were chosen for upgrading the uncovered defects in wetfinishing. Waxy, metallic, corrected grain and cationic finishing were employed against the conventional resin finishing. With cationic finishing, an improved and upgraded leather was obtained with better natural look or appearance of grain, good covering and comparable physical and organoleptic properties and better grade.
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    Extraction and Characterization of Chlorogenic Acid from Coffee Husk and its investigation of Applicability as Preservative in Leather Processing
    (Addis Ababa University, 2018-06) Daniel, Tesfaye; Shegaw, Ahmed (Assoc. Prof.)
    Leather is a perishable material so it has to be preserved from attack of microorganisms. In leather processing steps, skins can be stored at pickle, wet blue, crust and finished stages. Wet blue preservation is prevents the leather from fungal attack and its commercial carried out using TCMTB based chemicals. This TCMTB based commercial chemicals has adverse effect on human health as well as on aquatic lives. Chlorogenic acid, the major active component of coffee husk, extracted by varying solvent, extraction time and solvent to sample ratio using Soxhlet extractor. Twenty Four extractions were randomly done and results were analysed using Design Expert software version 6.0.8. The extraction procedure using Methanol as solvent, extraction time of 4 hours and 10:1 ratio of sample to solvent resulted as the highest value, which is 681 ppm. The minimum yield (468ppm) was obtained at Ethanol solvent, extraction time of 6 hours and 5:1 ratio of sample to solvent. Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, Escherichia coli and Aspergillus niger were obtained and tested for the susceptibility and it was found to be Aspergillus niger, a fungi, is more susceptible or sensitive than both gram positive and gram negative bacteria to Chlorogenic acid extracted from coffee husk. The Minimum Inhibitory Concentration (MIC) for Aspergillus niger was found to be 62.5µg/mL. The wet blue preserved using the extracted Chlorogenic acid was tested for its resistance to fungal attack and resist any attack till 15 days. The wet blues were processed to crusting and tested for its strength properties and found to have no change of those properties upon the use of Chlorogenic acid for preservative. The waste water from the process were tested and showed significant minimization of COD and TSS.
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    Study on The Specialty of Ethiopian Highland Hair Sheep Skin to Make Glove and Cabretta
    (Addis Ababa University, 2014-09) Rediate, Tsegaye; Babu, N. K. Chandra (PhD); Rao, J. Raghava (PhD); Rathinam, Aravindhan (PhD)
    Ethiopian highland hair sheep skins have a wide importance mainly as a source of foreign exchange to the country from the leather industry. The consumption of these products is high for reasons of high quality to make glove, cabretta as well as for sport goods leathers. The present work describes the study on characterization of the Ethiopian highland hair sheep skin by carrying out histological analysis using light microscope and scanning electron microscope (SEM). Indian hair sheep skin has been used for comparing the characteristics features. Various features of the Ethiopian highland sheep and Indian red hair sheep skins such as thickness distribution of the skin, layers in the epidermal area, fibre size, fibre orientation and the interweave in the dermal area, the hair pore count and grain to corium ratio have been determined. In addition to this physico-chemical characteristics of hair sheep skins have been analyzed using different equipment and procedures. From the result of physical and chemical characteristics it could be inferred that tensile and tear strength of the leathers from Ethiopian highland hair sheep skin is higher than Indian hair sheep skins. Chemical characteristics such as the hydroxyproline content, collagen, nitrogen, glycoprotein, hide substance of the skins have been determined and in all result Ethiopia highland hair sheep skins are better compared to Indian material. From the histological, physical and chemical characteristics of the Ethiopian sheep skins, it could be inferred that the inherent character of these skins make it suitable for making of glove and cabretta leathers.
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    Approaches to Near Zero Utilization of Water in the Post tanning Operations of Leather Processing
    (AAU, 2014-09) Solomon, Fessehaye; K J., Sreeram (PhD)
    Any industrial activity would generate waste, whose form would be as solid, liquid and/or gas. While industrialization is important to a nation’s economy, the wellbeing of human kind is even more important. The conflict for water between mankind consumption and industrial activity is increasing day by day as the population is increasing. An industrial activity like leather processing is a water intensive process, with most of the industries consuming 35 L of water to process every kilogram of hide/skin. While it is easy to wish away an activity like leather processing, an analysis of the relevance of this industry to Nation building would reveal that this is the only industry that uses a byproduct of meat industry, viz., skin and converts it into a fashion commodity. In the transformation, a host of rural men and women are involved directly or indirectly. For the nation, it is a good source of export income. This research work is one of an out-of-the-box thinking of systematic reduction and utilize known concepts of recycle, reduce or recovery of used water from processing. For this, the methodology has relied upon the replacement of water with environmentally benign and clean/green solvent for transporting chemicals into the skin matrix instead. The work consists of identifying the appropriate solvent or solvent mixture that a) did not have any adverse effect on the fibre structure, b) where a significant number of leather auxiliaries could be dissolved or dispersed and c) could be easily recovered and reused. The combination of solvents was selected from amongst reported clean/green solvents and the solubility / stability of the auxiliary dispersions determined by the measurement of the zeta potential of the system. The initial interaction of the dispersed auxiliaries with skin matrix being one of adsorption, various models of adsorption can be fitted to understand the nature of binding. The physical and visual properties of developed leathers have also been compared.
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    Study on Effect of Drying Techniques on Area Yield and Quality of Leather
    (AAU, 2018-06) Endale, Dabeta; Belay, Woldeyes (Prof.); Nishad N., Fathima (PhD)
    Drying is an important process in leather making in which tanning agents, dyestuffs and fat- liquoring agents combine with collagen further and water is evaporated to fulfill the demands of final leather product, therefore drying is one of mechanical operation which has signif icant effect on leather chemical and physical properties. Using different techniques of drying in the processing of Garment leather affect the change in the area yield of the leathers as distinct from each other’s. The area yield has great significance for the commerce since the price of piece of finished garment leather is sold based on its area yield. In this research, the effects of normal, toggle and vacuum drying techniques on the area yield of garment leather and the quality of the garment leather dried under each techniques of drying characterized based on moisture content, softness, tensile strength and elongation at break, subjective property and Scanning Electron Microscope (SEM) analysis was studied. Moisture content, softness and tensile and elongation at break of leather steadily decrease with increase in drying period and area yield. More porous and less adhesion of fibre is obtained by toggle drying techniques and some grain surface damages observed in vacuum drying techniques from microscopic images. Toggle drying techniques for drying of garment leather is preferable drying techniques because of the better area yield of 14.5% with good tensile strength and more porous leather.
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    Studies on Development of Cleaner Beam house Process, Extraction and Characterization of Collagen from Fleshing Wastes
    (AAU, 2018-06) Demissie, Tsegaw; Shegaw, Ahmed (PhD); Madhan, Balaraman (PhD)
    The study presents the development of cleaner beamhouse processes to facilitate the extraction of collagen from fleshing waste. 0.8% offer level of alkali protease in soaking process is observed to be optimum for opening up the fibre texture of the hide, and to provide good yield of fleshing waste. In addition to this, complete removal of hair is still an issue of concern for unhairing using enzymes. CLRI had developed a novel protease for unhairing and the effectiveness of this protease for unhairing in the presence of lipase as co-enzymes was study and presented in this thesis. Experimental results indicated that 1% lipase followed by 4% protease treatment improved the unhairing efficacy. The enzymatically dehaired hide was further analyse by SEM, and the complete removal of hair in the experimental process (1% lipase followed by 4% protease) is further established. The reduction in pollution load parameters viz., BOD, COD, TOC, TDS and TSS is 89.375%, 88.57%, 85.79%, 47.37% and 48.57%, respectively with reference to conventional unhairing process. The leathers processed from optimized soaking and unhairing system showed comparable strength characteristics with reference to leather processed with chemical unhairing system. Hence a total bio-based beamhouse processing in leather manufacture was feasible. Fleshing from conventional lime and green fleshing wastes were used for the extraction of collagen, which is high value protein that can be used for a wide range of applications viz., tissue engineering, cosmetic, food, and wound healing and pharmacy application. Extraction of collagen had been carried out using acetic acid solubilisation and it is observed that collagen yield obtained from green fleshing (96.53%) is higher than lime fleshing (84.87%). FTIR, SDS-PAGE, CD spectra and thermal melting experiments are used for the characterization of collagen. It was confirmed that the extracted collagen from lime/green fleshing wastes were type I and also found to have similar properties. This study clearly establishes the development of cleaner beamhouse process and effective recovery of collagen from fleshing waste.