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Synthesis and Application of Novel Functional Material as Leather Flame Retardant 
by Bo Li, Jiaxun Li, Lixin Li, Xuanping Jiang and Zhengjun Li
Volume: 109      Number: 7     Page: 239-245     Year: 2014
A novel leather flame retardant was successfully synthesized from pentaerythritol, phosphorus oxychloride, melamine and tetrakis-hydroxymethyl phosphonium chloride (THPC) by three steps. Its structures and properties were characterized by FT-IR, elementary analysis, mass spectrometry, DSC and TG. It was applied to the manufacture of flame-retardant leather. The flame-retardant properties were investigated by the Limit Oxygen Index (LOI) test and Vertical Flame test. The effects of the flame retardant on physical-mechanical and handle properties of leather were evaluated at different conditions. The results show that this novel flame-retardant material can effectively inhibit leather burning, increase leather thermal stability and has effective flame retardant property. Furthermore, it has good synergistic effect for improving leather properties like fullness, softness, grain tightness, thus can meet requirements for leather flame-retardant technology.
 
 
Reuse of Solid Waste from Juice Industry (Citrus sinensis peel) in the Extraction of Antioxidants with Enhanced Activity through Polymer Encapsulates for the Preservation of Skin 
by M. Kumar, P. Velmurugan, K. Sreeram, J. Raghava Rao and B. Unni Nair
Volume: 109      Number: 7     Page: 231-238     Year: 2014
Bio resources are finding increasing applications in our day-to-day activities. Current research on the active ingredients of plant/fruit extracts has several applications. To widen their applications in various fields, suitable biocompatible carriers are needed which would increase the shelf life of the extracts. In this work, one such biocompatible carrier for encapsulation has been developed using PEG-Sodium alginate as a complex which will act as a model for any natural product extract viz., Citrus sinensis peel. The extract has been studied for its radical and nitrite scavenging activity, inhibition of -carotene bleaching and lipid peroxidation assay, before and after encapsulation in order to quantify the antioxidant activity in presence of the carrier. From the experimental results, better encapsulation of the antioxidant have been observed with increasing molecular weight of PEG, up to 8000 Da which led to an increased shelf life and sustained release. Antioxidant-PEG-8000-SA, 20:2:1 (APS-8000) mixture has been optimized and used for preservation of goatskin. The dehydration, rehydration and hydroxyproline assays reveal that, APS-8000 would be better alternative for the conventional sodium chloride preservation.
 
 
Unique Rare Earth Pigments for More Thermally Comfortable Leathers 
by Sri Parasara Radhika, Gladstone Christopher Jayakumar, Kalarical Janardhanan Sreeram and Balachandran Unni Nair
Volume: 109      Number: 7     Page: 224-230     Year: 2014
This paper reports the investigations carried out on the synthesis characterization and optical properties of a new class of rare earth based near infrared reflective yellow pigments as an alternative to toxic inorganic pigments. The rare earth yellow pigments can be prepared by employing calcination method. The present work reveals that the doping of molybdenum for ceria in gadolinium cerium lattice changes the color hue from cream white to dark yellow. The calcination temperature employed for preparation of these pigments was about 1000C. This temperature was found to be much lower than that required to achieve the intense yellow hue through conventional solid state calcinations reaction (above 1500C). X-ray diffraction data confirm the crystalline character of the pigments. The pigment thus developed serves as a potential candidate for NIR reflective pigments for leather applications on account of its NIR reflectance value of 96% in the wavelength region 1100 nm. Thermal images of the finished leather exposed to NIR light clearly indicate the lower heat retention character. The pigment properties were in good agreement with industrial requirements. They also serve as environmentally safer pigments.
 
 
Green Solution for Salinity in Tannery Wastewater: A Step Forward in Leather Processing 
by S. Saravanabhavan, P. Velmurugan, J. Raghava Rao and B. Unni Nair
Volume: 109      Number: 7     Page: 214-223     Year: 2014
The conventional leather processing method contributes to high salinity in wastewater due to the discharge of enormous amount of salts used for preservation. Hence, an attempt has been made to replace the salt with polyethylene glycol (PEG) to reduce the salinity in tannery wastewater. The molecular weight (MW) and percentage offer of PEG were standardized based on the rate of dehydration of hide matrix during preservation and rehydration of preserved hide matrix. The determination of hydroxyproline in spent soak liquors at various time periods during storage showed that the preservation of hides using PEG MW 2000 was more effective than sodium chloride. The reduction in total salinity by 43% is possible in tannery wastewater through PEG based preservation of raw hides. Functional characteristics of the experimental crust leathers are shown to be on par with control crust leathers. The developed greener process appears to be technically viable and economically acceptable alternative for salt based preservation.
 
 
Covalent Immobilization of Organophosphorus Hydrolase oto Insoluble Bovine Collagen Fibers 
by Yanhong Li, Xinju Jia and Biyu Peng
Volume: 109      Number: 6     Page: 197-206     Year: 2014
An organophosphorous hydrolase (OPH) was prepared and partially purified from Flavobacterium sp. The crude enzyme, with an activity of 1030U/g, was immobilized onto insoluble bovine collagen fibers (hide powder), instead of collagen membrane, through glutaraldehyde coupling. Optimal conditions of enzyme immobilization and properties of the immobilized enzyme preparation were investigated. Compared to glutaraldehyde tanned and chrome tanned hide powders, non-tanned hide powder showed higher immobilized enzyme activity. The optimal enzyme immobilization conditions are as follows: 10mg of enzyme was immobilized onto 500mg of hide powder in a 50mM phosphate buffer of pH 7.5 at 200C, and 20% glutaraldehyde offer (based on the hide powder weight) was used to couple the enzyme and collagen fibers. The enzyme activity yield was about 35% and the hide powder immobilized OPH has an enzyme activity of about 7U/g. The immobilized enzyme showed the same temperature and pH profiles as the free enzyme, and it performed at much higher pH and with better thermal stability. The Km value of the immobilized enzyme was a somewhat higher (0.388mM) than that of the free enzyme (0.215mM). The reusability test showed that about 85% activity was retained after 10 use cycles. After storing for eight months at 20oC, the residual activity of the immobilized enzyme preparation was 98%.
 
 
1-Butyl-3-Methylimidazolium Acetate as an Alternative Solvent for Type I Collagen 
by Jie Liu, Zhou Xu, Yi Che, Haojun Fan and Bi Shi
Volume: 109      Number: 6     Page: 189-196     Year: 2014
Low solubility and undesirable denaturation in conventional solvents continue to represent a significant challenge for efficient extraction, accurate characterization and versatile processing of collagen. In the present study, a room temperature ionic liquid (IL), 1-butyl-3-methylimidazolium acetate ([BMIM]Ac), was synthesized, and then evaluated as an alternative solvent for type I collagen. Real-time polarizing optical microscope observation indicated complete disintegration of hierarchical structure of collagen aggregates as solubilized in [BMIM]Ac at 25 oC. The solubility reached up to approximately 8.0 wt.% at 25 oC, more than ten times higher than that in conventional dilute acetic acid. In comparison with dilute acetic acid and recently reported chloridion ILs, high solubility of collagen in [BMIM]Ac at room temperature was ascribed to loose binding between [BMIM]+ and acetate, as well as stronger proton-accepting ability of [BMIM]Ac, which enabled rupture of those intermolecular hydrogen bonds and ionic bonds that stabilized collagen aggregates. However, such bond-rupturing effect was found selective at room temperature. As demonstrated by Fourier transform infrared, circular dichroism, atomic force microscope, and ultrasensitive differential scanning calorimetry analysis, [BMIM]Ac did not destroy the special triple-helical structure of tropocollagen molecules that had been identified as being of importance for the functional and bioactive properties of collagen. According to these results, the discovery of [BMIM]Ac as an ideal solvent for collagen may open up new possibilities for the chemistry and engineering of collagen, which has long been established as a readily accessible and renewable resource with many unique properties.
 
 
Green Synthesis of Monodispersed Iron Oxide Nanoparticles for Leather Finishing 
by M. Nidhin, R. Aravindhan and K. Sreeram
Volume: 109      Number: 6     Page: 184-188     Year: 2014
Industries worldwide, including leather, have had to phase out pigments based on lead, chromium(VI), cadmium etc. due to the toxicity associated with these transition metal ions. Coupled to this phase out is also a need to enhance the functional properties of the otherwise safe pigments, with low use, so as to avoid wastage. In this direction, the use of nano-pigments is slowly coming into vogue. This paper explores the advantages of replacing an otherwise popular brown pigment the hematite (-Fe2O3) with nanosized oxides in leather finishing. Any synthesis methodology for nanoparticles is sustainable only when green methods are employed for their synthesis. This work takes adequate care in employing an environmentally friendly methodology based on biocompatible polysaccharide starch as a template. The advantages of this method, such as the monodisperse character of the oxide, low particle size, ability of the carbon residue from the template to aid easy homogenization of the pigment to the finish formulation have resulted in excellent covering of surface, improved levelness, no overloading of grain, excellent physical properties and ageing resistance.
 
 
Transposition of Chrome Tanning in Leather Making 
by Chao Wu, Wenhua Zhang, Xuepin Liao, Yunhang Zeng and Bi Shi
Volume: 109      Number: 6     Page: 176-183     Year: 2014
To avoid the release of chrome from leather into post tanning effluents and the generation of chrome shavings, an inverse chrome tanning technology based on wet white was investigated. Conventional bated pelt was firstly tanned using an amphoteric organic tanning agent (Tingjiang white tanning agent, TWT) without pickling. Then, the TWT tanned wet white was directly processed with conventional post tanning processes. Chrome tanning was transposed to the end of the post tanning. The wet white had a shrinkage temperature (Ts) around 85oC that met the needs of shaving operation, and did not generate chrome shavings. The Ts and Cr2O3 content of the leather, by using this inverse chrome tanning technology, were higher than those of the conventional chrome tanned leather. With this inverse technology, the chrome output was reduced by 48%, mainly because no chrome was released from leather in post tanning processes. Meanwhile, the volume of chromium-containing wastewater discharged from the inverse processes was barely 31% of that from the conventional processes, which makes it much easier to collect and recover chromium from the effluents. Additionally, the tensile strength, tear strength and general appearances of the leather produced by the inverse technology were comparable to those of the conventional chrome tanned leather.
 
 
STUDIES OF ETHIOPIAN SHEEPSKINS AS AN OPPORTUNITY FOR VALUE ADDITION PART II: OPTIMIZATION AND CHARACTERIZATION OF WANKE UPPER AND GARMENT LEATHERS 
by H. MOHAMMED, G. AYSANEW, R. ARAVINDHAN, J. RAGHAVA RAO and N.K. CHANDRA BABU
Volume: 109      Number: 5     Page: 161-170     Year: 2014
Ethiopian tanners face a shortage of raw material input for the production of leather. The government strategically planned for importing raw skins from neighboring countries and also for effective utilization of available raw material resources in the country. The meat of Wanke sheep is in high demand in international markets, but the skin commands low price not only due to low availability but also less demand by tanners due to natural problems associated with the skin. Hence, tanners treat the skin as a reject. The problems of Wanke skin include high natural fat deposition, thin substance and low strength. Usually, leathers made out of Wanke skins have low selections compared to Ethiopian sheep skins and are mainly utilized for making lining leather. In this work, efforts have been made to develop a process technology for making high value leathers with improved properties from Wanke sheepskin.
 
 
NUTRIENT BALANCE IN AEROBIC BIOLOGICAL TREATMENT OF TANNERY WASTEWATER 
by JIANFEI ZHOU, YA-NAN WANG, WENHUA ZHANG AND BI SHI
Volume: 109      Number: 5     Page: 151-160     Year: 2014
The effect of nutrient composition of tannery wastewater on aerobic biological treatment, particularly on the removal of ammonia nitrogen (NH3-N) and total nitrogen (TN) was investigated based on the theory of nutrient balance. During the biological treatment of conventional tannery wastewater, total organic carbon (TOC) and total phosphorus (TP) were almost exhausted. However, the removal of TN was unsatisfactory, suggesting that tannery wastewater contains excessive N source and insufficient C and P sources. When extra C and P sources were added together into the wastewater, the removals of NH3-N and TN increased significantly. Under the optimal ratio of TOC:TN:TP (10:1:0.2), the removals of NH3-N and TN were 100% and 80%, respectively, and the added C and P sources were almost consumed by activated sludge. This means that a good nutrient balance was achieved in this condition. Accordingly, when ammonium salts are replaced by organic acids and phosphates in the deliming and bating processes, it is reasonable to assume that the change of wastewater composition would favor the aerobic biological treatment of wastewater.