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Microbial Kerainase and its Potential Application in the Management of Tannery Hair Waste 
by A. Onyuka, M. Bates, A. Covington and P. Antunes
Volume: 109      Number: 12     Page: 425-430     Year: 2014
Up to 40 tons of solid hair waste can be generated during the industrial leather manufacturing process posing disposal problems. Composting is considered a viable technology to recycle the hair waste for application in agriculture. However, due to its constituent protein, keratin hair is remarkably resistant to degradation under natural conditions. The aim of this study was to isolate keratin degrading bacteria and evaluate their ability to degrade hair as a preliminary study towards developing a biocatalyst to improve hair degradation during composting. Subsequently, a keratinolytic microorganism was isolated from a nutrient alkaline culture (pH 11) with bovine hair as the source of carbon and nitrogen. The microorganism, identified as belonging to the Bacillus species grew optimally in the temperature range of 40 50C. The partially purified microbial keratinase exhibited broad substrate specificity at pH range 7.5 10. The pH and temperature of optimum activity was determined at 9.0 and 50C, respectively. Scanning electron microscopy assessment of the hair samples showed complete fragmentation of the structure after incubation with the microbial keratinase. Hence, the microbial keratinase has greater potential application as inoculant to enhance biodegradation of tannery solid hair waste during the composting process.
 
 
Elucidation of Probable Mechansm for Biocidal Resistane in Skin-borne Bacillus subtilis 
by S. Kavitha, B. Swarnakuari, N. Chandra Babu, M. Vahini and C. Vandhana
Volume: 109      Number: 12     Page: 418-424     Year: 2014
An attempt has been made in the present investigation to determine the probable mechanism through which a skin-borne bacterium Bacillus subtilis might develop resistance against a dithiocarbamate based biocide. Changes occurring in the cell wall constituents and morphology in the cells grown at sub-optimal level concentrations of biocide were studied based on which the probable mechanism of buildup of biocidal resistance has been proposed. There has been considerable change/reduction in cell wall constituents, peptidoglycan, diaminopimelic acid and teichoic acid due to the presence of biocides. By propidium iodide staining technique, the cell wall permeability has also been found to be reduced. The morphology of the cells as studied using scanning electron microscopy reveals that there is a shortening of rod shape of the cells due to the action of the biocide. Based on the results of the study, it is proposed that the skin-borne Bacillus subtilis encountered in leather processing might develop resistance through changes in the cell wall constituents and reduction in the cell wall permeability.
 
 
Cool Glove Leathers Made Using Themoresponsive Syntans 
by A. Prakash, M. Ragul, J. Raghava Rao and N. Nishad Fathima
Volume: 109      Number: 12     Page: 411-417     Year: 2014
Protection is the main function of gloves; also comfort of the wearer has to be kept in mind while making gloves without compromising on strength and flexibility. Body dissipates heat in the form of sweat; sweating through hands is likely to be more while using gloves in relatively hot weather conditions resulting in discomfort and slipperiness. In order to overcome these problems there is a need for development of materials, which can respond to temperature changes providing comfort and protection. In our current study, Phase Changing Material (PCM) was encapsulated into condensate polymers of melamine formaldehyde for preparation of thermoresponsive syntan. The syntan was characterised using different techniques such as Differential Scanning Calorimetry (DSC), Thermo Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). Glove leathers made using this syntan were termed Cool glove leathers as they showed thermoresponsive behaviour, which exhibited a temperature difference of 1.50.5 C to that of control leather samples with 0.50.4 C. The cool glove leathers were tested for various properties like strength, organoleptic and thermoresponsive function.
 
 
Preparation and Characterization of Collagen Grafted by Styrene-butyl Acrylate and its Application for Paper Sizing 
by Sufeng Zhang, Qun Wang, Wanwan Dou, Xuechuan Wang and Taoao Qiang
Volume: 109      Number: 12     Page: 404-410     Year: 2014
Collagen extracted from tannery wastes was modified by grafting it with molecular chains formed by polymerizing vinyl and acrylate monomers. The novel collagen product obtained in this manner was tested as paper sizing agent. The structure and properties of modified collagen were characterized by FTIR, STA and XRD. Results indicate that polyvinyl chains were grafted onto collagen, primarily in its crystalline regions. This modification significantly improved the thermal stability of collagen. Then the modified collagen emulsion alone (MCE), or combined either with gelatinized starch (MCE+S) or commercially produced styrene-acrylic emulsion (MCE+SAE), was applied to the surface of corrugating medium. The properties of these products were compared with those of commercially produced medium sized by SAE+S. Sizing by (MCE+S) increased the ring crush index by 12.7% and tensile index by 13.4%. In a Cobb60 test the corrugating medium sized by a blend of modified collagen and styrene acrylic emulsion (MCE+SAE) absorbed less water than commercially produced medium sized by SAE+S. Abbreviations Used: US = Unsized paper. SAE+S = Paper sized by styrene acrylic emulsion and starch. MCE = Modified collagen emulsion. MCE+SAE = Modified collagen emulsion couple with styrene acrylic emulsion. MCE+S = Modified collagen emulsion couple with gelatinized starch.
 
 
A Cleaner Al2O3-ZrO2/MMT Nanocomposite Adsorbent Based on Al-Zr Tanning Waste 
by E. Tao, Ma Hong-Rui and Li Yun
Volume: 109      Number: 11     Page: 389-396     Year: 2014
A nanocomposite absorbent of Al2O3-ZrO2/MMT (AlMMT) was produced by intercalating Al2O3-ZrO2 into interlayers of MMT (montmorillonite), which was from the waste of Al-Zr tanning agent used when making leather. The AlMMT nanocomposite was characterized by XRD, TEM and SEM. The factors that affected the adsorbtion process of Cr3+ were also analyzed. Cr3+ was adsorbed on the surface of AlMMT. The adsorbing processes were mainly surface adsorption, ion exchange and electrostatic forces. Cr3+ adsorption kinetics and isotherm of AlMMT can be described by pseudo-second-order kinetics and Langmuir equation at 25oC.
 
 
Cyclic Dechroming Process for Chrome Shavings by Coordination Substitution Reaction and Photocatalysis 
by Yuling Tang, Zaiyin Hu, Huiyun Liu, Wei Hu and Ru Wang
Volume: 109      Number: 11     Page: 380-388     Year: 2014
The cyclic dechroming process for chrome shavings by method of coordination substitution reaction and photocatalysis was investigated. Using EDTA (ethylene diamine tetraacetic acid) as dechroming agent and NaOH as recovery agent, the process conditions were optimized through the orthogonal tests. The removal efficiency of chrome from chrome shavings was 98.88% when dechroming was undertaken in 0.03 mol/L EDTA solution at 50 and pH 6.0 for 14 days with stirring and then treated in the same solution under ultraviolet (145 W, 254 nm) for 8 days, and the loss of collagen was 5.31%. The chrome was separated from the dechroming solution as Cr(OH)3 precipitate by adding NaOH into the dechroming solution (conc. of NaOH = 1.00 mol/L) and stirring at 70 for 1 d. The solution containing EDTA was reused for dechroming again after filtering and adjusting pH to 6.0 by sulfuric acid and the removal efficiencies of chrome were all more than 97% in triplicate trials. The structure of collagen after chrome extraction was characterized by SEM and FT-IR. The results indicated that the triple helix structure of collagen was well preserved. The thermal stability of collagen after chrome extraction was characterized by DSC; the results indicating that it was in conformity with rawhide. The dechroming process without strong acid and alkali can prevent collagen from hydrolysis. A certain amount of Cr(VI) appeared by adding alkali in precipitating Cr and recovering EDTA. However, Cr(VI) was reduced to Cr(III) when pH of the recovered EDTA solution was adjusted to 6.0 by adding sulfuric acid. This kind of closed recycling dechroming technology can reuse dechroming agent, and thus avoid the elution of wastewater during dechroming process.
 
 
Study on Reutilization of Wet-blue Leather Wastes for the Production of Regenerated Leather Composite 
by Chen Qian
Volume: 109      Number: 11     Page: 372-379     Year: 2014
In this paper, the possibility of making use of wet-blue leather wastes on a large scale through a nonwoven method was investigated. Firstly, collagen fibers were extracted from the wastes and their structure was characterized. The water absorbency of collagen fibers was tested and compared with that of wool and silk fibers. Then, we successfully developed a composite of regenerated collagen fibers on a base layer of PA/PET and viscose fiber, and tested their physical properties. The results indicated that most of the extracted short collagen fibers existed in bundles, their fibers length were in the range of 25-45 mm, and their finesse was in the range of 2-5m. The extent of water absorption of collagen fibers was similar to that of wool fiber. The collagen fiber composite on the base layer of PA/PET had good tensile and tearing strength. Moreover, the composite had good moisture permeability with the viscose fibers as a support base layer.
 
 
Micro-computed Tomography Studies for Three-dimentional Leather Structure Analysis  
by E. Bittrich, K. Schladitz, R. Meyndt, H. Schulz and M. Godehardt
Volume: 109      Number: 11     Page: 367-31     Year: 2014
The use of micro-computed tomography for the elucidation of three-dimensional microstructure of leather is described. Layers of leather, fiber bundles with their branches and inner structure are detectable. For the fine-fibered and dense-structured grain layer techniques with higher resolution are required, such as SEM. Problems encountered in image analysis with respect to automated segmentation are discussed and alternative solutions are presented.
 
 
Modeling a Strategic Raw Hides & Skins Supply Chain Network Suitable for Adoption of Chilling Method of Preservation in Decentralized Collection System 
by P. Narayanan, P. Prasad, D. Chandramouli and N. Chandra Babu
Volume: 109      Number: 10     Page: 353-362     Year: 2014
Salt Curing is a method that is widely used for the preservation of raw hides and skins worldwide and this leads to high salinity in tannery effluents. The treatment of such highly saline stream poses serious challenges, as pollution control norms for salinity are quite stringent in many countries including India. Chilling has been proven a most efficient method both in terms of cost and preservation efficacy for short-term storage but adoption in decentralized raw material collection systems prevailing in many developing and underdeveloped countries is a major challenge. In the present techno-management study, an attempt has been made to model a strategic supply chain network for collection and chilling of raw hides and skins suitable for such decentralized situations. Tamil Nadu state in India has been chosen for the pilot project as it contributes close to 50% of the tanning activity in India. Eight clusters have been formed by grouping the districts of Tamil Nadu based on the geographical location. The optimized location for the chiller in each cluster was found using gravity location model and the feasibility of transporting the raw hides and skins from slaughterhouse to chiller has been studied.
 
 
Pyrolysis of Chromed Leather Waste Shavings in Fluidized Bed 
by T. Simioni, E. Matos, V. Bacca, D. Perondi, M. Godinho and A. Dettmer
Volume: 109      Number: 10     Page: 342-352     Year: 2014
The leather industry generates a large amount of solid waste, which sometimes has pollution potential. Chromium is often present in this waste. Thermal treatment proves to be a promising method for the reuse of leather waste. The pyrolysis process involves heating the biomass in an inert atmosphere. The products are gas, oil and carbonaceous solid residue (char). The present study main objective is to investigate the production of useful materials from chromed leather waste shavings (CLWS) pyrolysis. This waste was characterized by chromium, total Kjeldahl nitrogen and ashes content. Volatile content, higher calorific value, thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM) were also determined. A fluidized bed reactor was used for the tests. The parameter varied in the experiments was the temperature (723 K and 873 K), and heating rates (0,25 and 0,4 K/s). The product fractions yield was evaluated, and was found that the pyrolysis temperature of 873 K has a higher yield of oil. The oil was characterized using the technique of Fourier transform infrared spectrophotometry (FTIR) and gas chromatography with mass spectrometry, that showed the presence of oxygenated organic compounds (alcohols, phenols, ketones) and even non-oxygenated organic compounds (alkanes, alkenes, aromatics) in its composition. The char was characterized according to the techniques of SEM and energy dispersive spectroscopy (EDS). According to the results of these analyses, the char has a porous morphology and is basically composed of C, Cr, Na, Mg and Cl. Thus, the pyrolysis of CLWS appears as a promising alternative for the treatment of these residues, and to obtain useful products.