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Öğe Antioxidant effect of tannic acid on formation of formaldehyde and hexavalent chromium compounds in leather(Ege Universitesi, 2014) Menteş Çolak S.; Dandar U.; Kiliç E.The presence of formaldehyde and hexavalent chromium in leather products, results from the inclusion of formaldehyde in chemical manufacturing process of industrial chemicals, and the oxidation of Cr (III), which is used as tanning agent in leather tanning industry, to Cr (VI) under certain conditions. In this study, wet-blue sheep skins were treated with different concentrations of tannic acid such as 0.1, 0.5, 1, 2 and 3% at retanning process in order to investigate the antioxidant effect of tannic acid on chromium (VI) and free formaldehyde formation in leather. For this purpose following the retanning process, formaldehyde content of leathers were analyzed according to ISO TS 17226 method with HPLC device. Hexavalent chromium formation was forced by exposing leather samples to accelerated ageing conditions, such as high temperature and UV. The chromium (VI) content on leather samples were determined in accordance with TS EN ISO 17075 standard procedure. The physical properties of final leathers were also investigated. Inhibitory efficiency of tannic acid both on hexavalent chromium and formaldehyde was attained at concentrations above 1% tannic acid. The offer of 3% tannic acid fulfilled the Eco-label criteria for footwear and provided lower chromium (VI) values than 3 ppm. Besides, all four tested concentrations of tannic acid maintained the formaldehyde concentrations under restricted limits. The improvement effect on the physical characteristics of leathers was observed in direct proportion of increasing tannic acid concentrations. The results indicated that tannic acid has a remarkable antioxidant effect on chromium (VI) and free formaldehyde formation in leather.Öğe The average-dominating of a graph(2009) Dündar P.; Kiliç E.; Balci M.A.The vulnerability is one of the most important concepts in network design. Vulnerability can be considered as the resistance of the network after any breakdown in its nodes or links. Since any network can be modelled by a graph, vulnerability parameters on graphs also work on network types. The vertices and the edges of a graph correspond to the processors and the links of the network, respectively. The measure parameters about the vulnerability of a connected graph which are mostly used and known are based on the Neighbourhood concept. Neighbour-integrity, edge-integrity and accessibility number are some of these parameters. In this work we defined and examined the Average-Dominating of a connected graph as a new global connectivity measure. It takes account the neighbourhoods of all pairs of vertices. First we define the pair dominating of any two vertices such as u and v in a graph as to be the maximum number of vertices which dominate both u and v in G. It is denoted by D(u,v). Then latter we define the average dominating of G denoted by D¯(G) as, (Equation Presented) , where G is a graph of order n. ©2009 IEEE.Öğe Carbon footprint and energy balance of biodiesel produced from tannery fleshings(American Leather Chemists Association, 2014) Kiliç E.; Puig R.; Baquero G.; Zengin G.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.Öğe Carbon footprint of a tanning company in Turkey(International Union of Leather Technologists and Chemists Societies (IULTCS), 2015) Kiliç E.; Puig R.; Zengin G.; Zengin C.A.Carbon footprint analysis is gaining a role of primary interest within leather production regarding sustainability issues. The knowledge of carbon emissions and the environmental impact of production is indispensable for improving the performance to achieve a sustainable industrial production. In this study standardized life cycle assessment methodology (ISO 14040) is applied in Turkish leather industry. Corporative carbon footprint of a representative Turkish tanning company in year 2013 was analyzed through the global warming potential impact category defined by CML 2009, which enables quantification of the life cycle greenhouse gas emissions from tanning processes measured in kg of CO2 equivalent emissions. The most significant environmental impact sources responsible for creating more greenhouse gas emmissions in production processes are also identified. The results obtained from this study may provide a useful decision framework for incorporating sustainability concerns, follow-up of the most cost-effective carbon mitigation strategies and tackle with future carbon pollution regulations in leather industry. Additionally, carbon footprint calculation provides information to consumers in terms of product carbon labels or guides enabling more carbon efficient products. Potential reductions in greenhouse gases by promoting sustainable production and achieving the transition to a low carbon sustainable economy will provide new opportunities in the green market for leather industry.Öğe Deliming with weak acids: Effects on leather quality and effluent(Society of Leather Technologists and Chemists, 2008) Çolak S.M.; Kiliç E.Effluent which has a high ammonium content is produced as a result of traditional deliming operation using ammonium salts. Ammonia is converted into nitrate by the nitrogen cycle in nature and ammonium salts discharged into natural water sources have toxic effects on living organisms.In this research weak acids were used to delime in studies on sheep skins to reduce the ammonium load that originates from deliming. Beside the deliming effect of acids, the N content of the resulting discharge water was determined and the effect of these methods on the quality of the leather was studied. The data obtained from the study were compared with the traditional deliming methods and standards.Öğe Eco-friendly soaking process using tannic acid as an alternative bactericide(Polish Academy of Science, 2014) Zengin A.C.A.; Çolak S.M.; Zengin G.; Kiliç E.Eco-friendly leather processes based on the usage of natural products have become a potentially attractive issue for leather industry during the last few decades. Synthetic protective chemicals like bactericides used in most soaking process are known as hazardous substances and cause tannery effluents with high concentrations of Chemical Oxygen Demand (COD). In the present study, the effect of tannic acid on microorganisms, skin, wool and effluent were investigated in order to demonstrate the applicability of tannic acid in soaking process instead of commonly used bactericides. The bacterial load (cfu/ml), COD and Nitrogen Content (N) of the soaking effluents and Total Kjeldahl Nitrogen (TKN) content of skins and wools were investigated. Application of 0.5 and 1 wt% tannic acid concentrations was more effective than commercial bactericide, while comparable results were achieved by 0.1 and 0.3 wt% tannic acid. The application of tannic acid for soaking process resulted in lower COD and N values of effluents. The results show that tannic acid has the potential to be an alternative, eco-friendly bactericide for leather industry by reducing the pollution of leather soaking process. © Copyright by Polish Academy of Sciences and Institute of Environmental Engineering of the Polish Academy of Sciences 2014.Öğe Finding a fault tolerant routing on neighbour-faulty hypercube(2004) Dündar P.; Kiliç E.It is important for a communication network to route data efficiently among nodes. Efficient routing can be achieved by using node-disjoint paths. Routing by node-disjoint paths among nodes cannot only avoid communication bottlenecks, and thus increase the efficiency of message transmission, and also provide alternative paths in case of node failures. The one-to-one routing constructs the maximum number of node-disjoint paths in the network between the two given nodes. Optimal algorithms have proved sufficiency in designing efficient and fault tolerant routing algorithms on hypercube networks. In this article, firstly, we give the concepts of neighbourhood and accessibility in a graph, which is a model of a communication network. After, we give a fault tolerant routing algorithm using cube algebra for faulty hypercube that is proceeded from neighbour notion.Öğe Ink dyes for leather industry(CSIR-CLRI, 2017) Adigüzel Zengin A.C.; Pourrasoul Sardroudi N.; Pourrasoul Sardroudi S.; Bitlisli B.O.; Kiliç E.Dyes and pigments offer significant potential for functional and aesthetic design of leather materials. Search for viable alternative leather colorants, which have the potential to develop new creative designs and provide functionality are presently in focus. In this context application of alternative textile dye substances that can offer special effects to leather have increasingly gained importance. In this study, the potential application of ink dyes in leather industry was investigated as an alternative to conventional dyes for the production of leathers with high fastness properties. For this purpose, leather dyeing recipes were developed by using two different ink dyes including latex and dye based ink dyes and applied at dying process of metis type crust leathers in order to produce high performance leathers. The quality performance of dyed leathers were investigated in terms of colour measurements, to-and-fro and crockmeter rubbing fastness, before and after washing leathers in a washing machine under specified conditions according to ISO 15702 standard. The colour measurements prior and subsequent to washing process were determined with Minolta CM-3600A spectrophotometer. To-and-fro rubbing and crockmeter fastness properties were examined in accordance with TS EN ISO 11640 and ASTM D5053 standards respectively. The results of the study showed that latex and dye based ink dyes could be used as a newly adapted dye group and applied successfully in leather dyeing process for the production of leather goods with high fastness properties.Öğe Ink dyes for washable leathers(Certex, INCDTP-ICPI, 2016) Zengin A.C.A.; Sardroudi N.P.; Kiliç E.; Bitlisli B.O.Inks, contain pigments or dyes in liquid or paste form, are used to color an image, text, or design. Although some patents describing the ink jet printing methods for textile and leather were found, no report was found addressing the application of ink dyes in leather dying process and determination of washing and other fastness properties. In this study, the potential application of ink dyes in leather industry was investigated as an alternative to conventional dyes for the production of washable leathers in dying process. For this purpose, leather-dyeing recipes were developed by using two different ink dyes and applied at dying process of metis type crust leathers in order to produce washable leathers. The quality performance of dyed leathers were investigated in terms of color measurements, to-and-fro rubbing fastness, crockmeter rubbing fastness, and light fastness characteristics before and after washing leathers in a washing machine under specified conditions according to ISO 15702 standard. The color measurements prior and subsequent to washing process were determined with Minolta CM-3600A spectrophotometer. Toand- fro rubbing, crockmeter and light fastness properties were examined in accordance with ISO 11640, ASTM D5053 and ISO 105-B02 standards respectively. The results of the study showed that ink dyes could be used as a newly adapted dye group and applied successfully in leather dyeing process for the production of washable leather goods. © 2016 Certex, INCDTP-ICPI.Öğe A new vegetable tanning material for leather industry: Acacia nilotica L.(International Union of Leather Technologists and Chemists Societies (IULTCS), 2015) Özkan C.K.; Zengin A.C.A.; Dandar U.; Zengin G.; Kiliç E.Tanning is the most important stage giving the required characteristics to raw materials used in leather industry. Chromium salt is still the most preferred tanning material due to the leather properties of the final products. However, ecological awareness, restrictions and legislations have led the tanners and researchers to seek alternatives to chromium tanning system. Numerous alternatives such as vegetable tannins, titanium, zirconium, aluminum, oxazolidine, starch, silica, polymers, syntans etc. have been investigated to overcome the arising ecological problems. Although there was no fully replacement of chromium salt yet, the tendency is still towards to chromium-less production and the production of metal free leathers. In this study, a new vegetable tanning material extracted from the fruit of Acacia nilotica L. was used in the tanning process of the leather industry. The tannin content, the influence on especially the shrinkage temperature, and final physical properties of leathers such as tensile strength, elongation %, tear strength and color measurements have been investigated. Comparable results with commonly used vegetable tannins were obtained from the extract of Acacia nilotica L. The results showed that the extract of Acacia nilotica L. could be the potential new vegetable tanning material also alternative to metal tanning and other tanning systems for leather industry.Öğe Oxidative chromium recovery from tannery sludge(International Union of Leather Technologists and Chemists Societies (IULTCS), 2011) Kiliç E.; Font J.; Puig R.; Çolak S.; Gürler D.As a result of increased environmental awareness and strict environmental legislations, it is necessary to develop cost-effective and environmentally acceptable remediation solutions for high chromium containing tannery sludge. In this paper, an oxidative chromium recovery treatment is presented. Dewatered tannery sludge samples were treated with hydrogen peroxide on a laboratory scale. The main steps of H2O2 treatment include Cr(III) oxidation to Cr(VI) and extraction with sulfuric acid solution at pH 2. H2O2 treatment enabled to extract 70% of chromium within less than 4 hours at room temperature. The results indicate that hydrogen peroxide treatment is effective and the duration of the process is short and requires cheap chemicals and moderate conditions. Application of oxidative treatment to tannery sludge will provide economical benefit and environmental protection as it enables high percentage of chromium recovery. The removal of organic material in tannery sludge prior to chromium recovery treatment would probably increase the percentage of chromium recovery more than 70% due to the lower content of organic matter to bind the chromium. Investigations are in progress to improve the efficiency of oxidative recovery process.Öğe Plant derived Saponinaescin as an antimicrobial soaking agent(International Union of Leather Technologists and Chemists Societies (IULTCS), 2015) Zengin A.C.A.; Kiliç E.; Zengin G.In the soaking process various unwanted contaminants are removed and skins are rehydrated. It is usually carried out with synthetic surfactants including biocides, salts and enzymes, or chemicals formulated as a mixture of surfactant, biocide and enzyme preparations in the form of aqueous emulsions. In this research, the feasibility of using aescin, a plant-derived saponin from horse chestnut seed, as an alternative natural antimicrobial biosurfactant in soaking process was studied. The effect of aescin was investigated in terms of microbial load, total protein content and chemical oxygen demand of soaking residual floats. Soaking baths were treated using a commercial product of aescin with 98% purity and synthetic biocides. The antimicrobial activity of aescin saponin was tested by using different concentrations of sapogenin (0.125-1g) in soaking process. Comparable results to synthetic biocides were obtained from horse chestnut saponin applications. Increased total protein content of soaking liquor in spite of decreased microbial growth was a good sign of antimicrobial soaking character of aescin saponin. The results obtained from the study reveals that Aescin saponin has the potential to be an environmentally friendly alternative to synthetic surfactants and antimicrobial compounds for leather industry.
