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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.
 
 
Determination of the Reactive Dye Navy Blue Her in the Wastewaters of the Dyeing Processes of Chrome-tanned Leather 
by L. Santos, L. Crispim, N. Silva and N. Oliveira
Volume: 109      Number: 10     Page: 330-341     Year: 2014
One of the main environmental problems in the leather industry is the contaminant load and amount of effluent produced during the industrial process. From these effluents we can highlight those resulting from the dyeing processes that contribute to the increase of the COD and BOD of the discharged wastewaters. The aim of the present work is to develop and validate simple, rapid, specific, selective, precise, robust and economical UV-Vis Spectrophotometric method for the estimation of reactive dye (Navy Blue HER) in aqueous solutions and effluents of the dyeing processes of chrome-tanned leather. UV-Vis Spectrophotometric measurement was carried out at a wavelength of maximum absorbance of 610 nm using ultrapure water as the solvent. The developed method was validated with respect to specificity, selectivity, sensitivity, limits of detection and quantification, linearity, precision (repeatability, intermediate precision) and robustness. The calibration curve ( ) is linear (r2 = 0.99998) in the concentration range from 3.0 mg/L up to 48.0 mg/L. The limit of detection (LOD) and the limit of quantification (LOQ) are 0.206 mg/L and 0.624 mg/L, respectively. The analysis results and its statistical treatment have proved that this analytical method is specific, selective, precise and robust, and has good repeatability and intermediate precision. Thus the proposed method was approved for all the analyzed parameters, being therefore, properly validated, and can be successfully applied for the estimation of reactive dye (Navy Blue HER) in aqueous solutions and effluents of the dyeing processes of chrome-tanned leather.
 
 
Headspace GC-MS for the Determination of Halogenated Hydrocrabons, Ethers and Aromatic Volatiles in Fabric and Leather 
by E. Chorier, N. Blanc, J. Cannot and A Berthod
Volume: 109      Number: 10     Page: 322-329     Year: 2014
The content of volatile organic compounds (VOCs) was required in industrial products. Now, it is also sought in household products. The detrimental impact of VOCs on air quality and human health pushed state authorities to take measures to reduce their emissions and occurrence in circulating goods. A set of 28 VOCs including 20 halogenated alkyl and aromatic compounds, two ethers and six hydrocarbons was built as a model of most VOCs possibly encountered in leather and textile commercial products. A variety of leather and textile matrices were spiked with known amounts of the VOC mix. It is shown that the headspace (HS) extraction must last for 45 min at 90C to reach full recovery of the least volatile compounds (1,2-diclorobenzene) even if 80% and more recovery is obtained in 5 min at 90C for all 28 VOCs contained in 20 mg amounts of leather or textile samples. The single ion-monitoring (SIM) mode of the mass spectrometer was needed to quantitate several VOCs overlapping in the GC chromatogram. The HS GC-MS method produced a statistically validated limit of quantification of 2.5 mg/kg (ppm) for all 28 VOCs analyzed.
 
 
Influence of Elastin Degradation on the Mechanical Properties of Leather 
by M. Schropfer, E. Kluver and M. Meyer
Volume: 109      Number: 9     Page: 306-313     Year: 2014
The influence of elastin degradation in leather on important mechanical properties was investigated. The elastin content of pelts and wet blues was determined by chromatographic analysis of desmosine, which is a specific and hydrolytically stable crosslinking. Analysis of pelts was performed directly, while chrome containing samples had to be detanned prior to analysis. It is demonstrated that elastase significantly reduces the elastin content. In contrast to often assured statements on the marked influence of elastase on softness, area yield, tensile strength and elongation of leather, our investigations showed no significant changes in the mechanical properties of leather as well as area yield, grain quality or softness after treatment with elastase. It is concluded that the impact of elastin on leather properties is generally lower than postulated before or that it is not pronounced in the dry state.
 
 
Carbon Footprint and Energy Balance of Biodiesel Produced from Tannery Fleshings 
by E. Kilic, R. Puig, G. Baquero and G. Zengin
Volume: 109      Number: 9     Page: 296-305     Year: 2014
This paper analyzes, from a life cycle perspective, the environmental performance of biodiesel obtained from leather industry fleshing waste (BDF). The indicators used for this environmental evaluation are: global warming potential (GWP) and energy return on investment (EROI). The contribution of each process-step in both GWP and EROI was determined. Transesterification of fat to obtain the BDF has been proved to be the most significant step in the process, mainly due to the consumption of methanol. A comparison between BDF and petroleum diesel obtained from non-renewable oil has also been performed using the same indicators. The results show a clear preference for BDF, although data from industrial real plants has to be considered in further works for BDF process to provide more accurate results.