Applications In Leather Industries Research Articles

Obtaining Bioemulsions Structured as "Networks" by Innovative Technologies

New bioemulsions structured like “networks” were created by innovative technologies based on: elastin/zinc hydroxide/ (bolaamphiphiles mixture: bis [2-butyl (sodium bis-thioacetate) sodium dicarboxylate 1,10 decanediyl ester] and/or sucrose diester)/ acetic acid/water, for improved surface properties development with applications in leather industry. We used in this research two “bolaamphiphiles”. Bolaamphiphilic molecules contain a hydrophobic skeleton (e.g., one, two, or three alkyl chains, a steroid, or a porphyrin) and two water-soluble groups on both ends. The interaction of surfactants with biopolymers in aqueous medium results in the formation of different association structures. There are various morphologies of biopolymer-surfactant association complexes depending on the molecular structure of the biopolymer and surfactant, on the nature of interaction forces between solvents and surfactant or biopolymer. The innovation consists in the technologies for obtaining novel micro and nanostructured bioemulsions, and the compatibilisation with film forming polymers for leather surface finishing. Elastin/zinc hydroxide micro and nanocomposites have been stabilized with bolaamphiphilic surfactants mixture: bis [2-butyl (sodium bis-thioacetate) sodium dicarboxylate 1,10 decanediyl ester and sucrose diester in a 1:1 acetic acid/water ratio, to increase the uniformity of nanocomposites. Micro and nanostructured composites like “networks” developed as a result of biopolymer-surfactants interactions for elastin/zinc hydroxide/surfactants mixture couple in acetic acid/water system are reported by SEM microscopy and DLS analysis. A special class of micro and nanoarchitectures is represented by structures organized as “network” assemblies. The novel micro and nanocomposites can provide the hybrid film with increased resistance to rubbing and water, and to deformation. Environmentally-friendly substrates with smart multifunctional features can be obtained for various applications.

A chrome-free combination tanning strategy: based on silicic acid and plant tannin

Silicic acid, commonly derived from cheap and easily available sodium silicate, has recently received great attention for application in leather industry to produce ecological leather with a cleaner approach. However, leather tanned with silicic acid alone is poor in storage stability, which limits its practical application in leather production. In this work, a new environment-friendly combination tannage based on silicic acid and plant tannin was developed to address this issue along with improving the comprehensive performances of leather. The obtained leather was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and so on. The results showed that compared with leather tanned with silicic acid alone, the leather tanned with this combination method possessed improved thermal stability, enhanced mechanical properties, acceptable softness, appropriate hydrophilicity, and especially enhanced storage stability. More importantly, the combination tanned leather with 1:1 of the mass ratio of silicic acid to vegetable tannin (composed of valonea extract and mimosa extract with the same weight) had more prominent comprehensive performances. In addition, the results demonstrated that hydrogen bonding played an important role in the combination tanning process. Furthermore, the hydrogen bonds generated between phenolic hydroxyl groups of polyphenols with silicon hydroxyl groups of silicic acid molecules inhibited the excessive condensation of Si-OH groups between themselves. Subsequently, the assessment of environmental impact revealed the value of BOD5/COD of the wastewater produced in this combination tanning process is more than 0.3, indicating the chrome-free combination tannage based on silicic acid and plant tannin was an environment-friendly tanning technology. These findings therefore indicated that a new chrome-free tanning method with silicon and biomass materials as main tanning agents has potential practical application prospect in leather production.Graphical abstract

Feather degradation efficiency and hide dehairing ability of a new keratinolytic bacillus halotolerans strain, isolated from a tannery wastewater

Here, we report a new keratinolytic-producing bacterium identified as Bacillus halotolerans 4BC based on 16S rRNA gene sequencing. 4BC strain isolated from a tannery wastewater, showed proteolytic activity when grown on keratin azure, bovine hair and feather meal agar plates. B. halotolerans 4BC degraded almost 88% of chicken feathers after 10 days of cultivation in feather powder broth at pH 8 and 37°C. It was also efficiently able to degrade bovine hair keratin, despite the complexity of this substrate in comparison to feather keratin. The effects of different liquid to substrate ratios, inoculum sizes and incubation times on keratinase production were studied using response surface methodology to find the optimum conditions required for maximum B. halotolerans keratinase yield. The maximum keratinase yield (1059±53 mU/ml) was found under the following conditions: incubation period of 10 days, liquid/solid ratio of 5 and inoculum size of 2.3 % v/v). The crude enzyme exhibited a remarkable activity and stability under high temperature and alkaline conditions (pH 10 at 80°C). Additionally, the touch-visual and histological results demonstrated that the enzyme treated dehaired hides exhibit similar or improved characteristics without damaging the collagen layer, which makes the crude keratinase a potential effective and eco-friendly candidate for application in leather industry to avoid pollution problems associated with the use of chemicals.

Preparation and characterization of waste papers based composites and their applications in leather industries

In this work, the utilization of waste paper in the preparation of cellulous-based composite is described, with latex as a binder. Paraffin wax and acrylic woven fibers were also used at various weight ratios to get the best mechanical and physical properties. The results were compared with the performance the Dixon, regularly used material in shoes manufacturing. The following tests were performed: compression resistance, density, water absorption, shrinkage, and moisture content. Manual method was employed in the preparation of test specimens in addition to laboratory forging machine for finishing of the specimens. Results of compression test (Modulus of elasticity, compressive strength, resistance to crushing) of the Specimens that contain pulp paper and reinforced with latex and acrylic fibers and low content of paraffin wax showed the highest resistance to compression, The increase of additives contents within the mix resulted in an increase in density. To mimic the real application conditions of the insole, the specimens were subjected to water absorption test by irrigation for 2 hours. The best specimen compositions for the water resistance test are those with high (5-10%) wax content due to the fact that the wax is a water repellent material. The shrinkage is another important parameter for the use of the composite in shoe industry. Result of shrinkage and humidity of all specimens show comparable results to commercially available and Dixon are also very close to the requirements of the specification of leather industry. However, in comparison with the available carton and dixon, our specimens contain from weight fraction (50g) waste pulp, (20g) latex, (4g) paraffin wax, (0.7g) acrylic fibers, proved comparable performance.

Bioutilization of poultry feather for keratinase production and its application in leather industry

Keratinase, a protease was produced from keratinolytic bacterium, Bacillus paralicheniformis MKU3, using poultry feather as substrate. Statistical analyses were carried out to enhance the activity of keratinase produced as a result of which enzyme activity was improved 6-fold yielding a maximum of 1872.5 U/ml and a specific activity of 1143.19 U/mg in 72 h. The keratinase produced was used to hydrolyze poultry feather waste which resulted in an almost 90% degradation by measurement of dry weight. Large scale production of keratinase was performed from 5-L to 500-L and it has been observed that an increase in the volume of bioreactor greatly improved the rate of production of keratinase along with a sharp decrease in production time. The keratinase produced was used to study dehairing on sheepskin and the efficiency was observed to be 100%. SEM and histochemical analysis on the skin confirmed efficient dehairing. The processed leather crust was further tested for physical strength and histochemistry wherein it has been proved that the quality of the leather crust produced is good. The environmental impact of the effluent produced as a result of dehairing was also assessed.

Alkaline-Enzymatic Hydrolysis of Wool Waste for Different Applications

Wool waste represents a valuable and renewable material with low level of valorization and high potential to be integrated in bioeconomy. The extraction of keratin from wool by-products generated by sheep breeders and furskin industry represents a valuable approach for reducing the environmental pollution with organic and heavy biodegradable waste and a possibility to use a renewable product in agriculture or different industries. Keratin hydrolysates were obtained by alkaline and alkaline-enzymatic hydrolysis with extraction yields of 16.4-43.5%. The obtained keratin hydrolysates were characterized by physical-chemical analysis (dry substance, nitrogen content, pH, ash etc), FT-IR spectra, Dynamic Light Scattering (DLS), electrophoresis (SDS-PAGE) and surface tension (VCA Optima XE). Alkaline and alkaline-enzymatic hydrolyses of wool waste showed the possibility to obtain different keratin polypeptides with suitable properties for application in leather industry or in agriculture.

Synthesis and characterization of photosensitive-fluorosilicone–urethane acrylate prepolymers

Two kinds of novel photosensitive-fluorosilicone–urethane acrylate prepolymers (Si-F15-IPDI-HEA/Si-F6-IPDI-HEA) were synthesized and characterized. Si-F15-IPDI-HEA and Si-F6-IPDI-HEA were able to form homogeneous mixtures with a number of acrylate monomers. Formulations with these prepolymers with common acrylic monomers exhibited high-polymerization rates and final double-bond conversion over 90% after irradiation for 60 s. It was found the final conversion decreased with the increase of the functionality of the monomer. The influence of the monomer and prepolymers on the properties of the UV-cured films was systematically studied. Thermostability property along with mechanical performance was improved with the increase of the functionality of monomers and prepolymers. A decrease of water absorption was also observed through water contact angle measurements. The UV-cured films of Si-F15-IPDI-HEA and Si-F6-IPDI-HEA possessed an excellent adhesion on the PU and PVC leather, providing a potential application in leather industry as a finishing and coating agent.

Eucalyptus globulusBark as Source of Tannin Extracts for Application in Leather industry

This paper reports the extraction of Eucalyptus globulus bark and a concentration strategy to obtain a phenolic-rich extract for application in the leather tanning industry. The profiles of total phenolic compounds (TPC) and tannins contents in water and dilute alkali as a function of extraction temperature and time led to the selection of the best conditions concerning extraction yield and selectivity. The selectivity profile for TPC and tannins was established, and a maximum of 20 g per kg of bark was found, representing 2.5 g per L of extract produced. On the basis of these results, the conditions selected to produce the extract for the application envisaged in this work were: water, 140 °C and 120 min. To increase the extract concentration, recirculation of the extracts over fresh bark (similar to a continuous bark extraction process) was performed and evaluated. The increment in phenolic compounds was about 4, attaining the final concentration of 8.6 g/L for TPC and 6.5 g/L for tannins. The final ext...

Effective Dehairing Properties of Keratinase from Paenibacillus woosongensis TKB2 Obtained Under Solid State Fermentation

Response surface methodology was employed for optimization of the culture conditions for keratinase production by a feather-degrading Paenibacillus woosongensis TKB2 under solid-state fermentation using chicken feather as substrate. The optimized culture conditions having 2.21 g of feather, with rice straw (2:1), moistened with distilled water (1:5, w/v adjusted to pH 8.5) and fermented for 72.07 h, resulted in 2.83-fold increased keratinase production compared to non-optimized condition. The enzyme efficiently dehaired goat hides within 14 h without the use of lime. The enzyme-dehaired goat skins were evaluated by mechanical, touch-visual and electron microscopy methods and were compared with conventional chemical treated skins. The results indicated that the enzyme treated dehaired skins exhibit similar or improved characteristics without damaging the collagen layer, which makes the crude keratinase a potential candidate for application in leather industry to avoid pollution problems associated with the use of chemicals.

Preparation, Characterization of Silicone Succinate Ester and its Application in Leather Industry

The silicone succinate ester surfactant (PMPS) was synthesized by the raw materials of polyether alcohol amine modified polysilosane (PAPS) and maleic anhydride (MA) at 90°C for 4.5h, and p-toluenesulfonic acid (PTSA) was used as the catalyst. Sulfated neatsfoot oil, oxidized-sulfited fish oil was mixed with PMPS to prepare a new leather fatliqour (F-1). The structure of the materials and PMPS were characterized by FTIR. The biodegradability of F-1 was analyzed by BOD5 and CODCr and the tissue slices of the leather samples oiled by PMPS were observed by Multimedia Microscope to study the fatliquoring effect. The waterproof properties and the fatliquored leather were determined. All the results indicated that the F-1 fatliquor has good fatliquoring effect.

Characterization of alkaline thermostable keratinolytic protease from thermoalkalophilic Bacillus halodurans JB 99 exhibiting dehairing activity

A thermostable alkaline protease produced from Bacillus sp. JB 99 exhibited significant keratinolytic and dehairing activity. The enzyme was purified by ammonium sulphate precipitation followed by CM-cellulose and Sephadex G-100 chromatography and resulted in 13.6 fold purification with 23.8% of recovery. The specific activity of purified enzyme was 2989.6Umg−l. Purified protease had a molecular weight of 29kDa and appeared as a single band. Gelatin zymogram analysis also revealed a clear hydrolytic zone, which corresponded to the band obtained with SDS-PAGE. The optimum pH and temperature for the keratinolytic activity was pH 11.0 and 70°C respectively and half life of protease was 70°C for 4h. N-terminal amino acid sequence of purified enzyme exhibited extensive homology with other thermostable alkaline proteases and inhibition by PMSF indicated serine type of protease. The Km and Vmax of protease for keratin substrate were 3.8±0.5mgml−1 and 15.1±1.6μmmin−1mg−1 and casein were 3.3±0.4mgml−l and 15.6±0.9μmmin−1mg−1 respectively. The enzyme efficiently dehaired buffalo and goat hide without damaging the collagen layer, which makes it a potential candidate for application in leather industry to avoid pollution problem associated with the use of chemicals in the industry. The enzyme also degraded chicken feathers in presence of reducing agent which can help poultry industry in management of keratin-rich waste and obtaining value added products.

Microbial proteases application in leather industry

Microbial proteases application in leather industry

Copolymerization of N‐substituted maleimide with alkyl acrylate and its industrial applications

AbstractA series of new copolymers with desired thermal stability and mechanical properties for applications in leather industry were synthesized from various substituted maleimides and alkyl acrylates. Polymerization was carried out by a free‐radical polymerization using benzoyl peroxide (BPO) as initiator. The monomers and polymers synthesized were characterized by elemental analysis, IR, and nuclear magnetic resonance (NMR). Interestingly, these polymers were soluble in common organic solvents. Copolymer composition and reactivity ratios were determined by 1H‐NMR spectra. The molecular weights of the polymers were determined by gel permeation chromatography. The homo‐ and copolymer of maleimide showed single‐stage decomposition (ranging from 300–580°C). The initial decomposition temperatures of poly[N‐(phenyl)maleimide] [poly(PM)], poly[N‐4‐(methylphenyl)maleimide] [poly(MPM)] and poly[N‐3‐(chlorophenyl)maleimide] [poly(CPM)] were higher compared to those of the copolymers. Heat‐resistant adhesives such as blends of epoxy resin with phenyl‐substituted maleimide‐co‐glycidyl methacrylate copolymers with improved adhesion property were developed. Different adhesive formulations of these copolymaleimides were prepared by curing with diethanolamine at two different temperatures (30°C and 60°C). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1870–1879, 2001

Copolymerization of 4-chlorophenyl acrylate with methyl acrylate: synthesis, characterization, reactivity ratios, and their applications in the leather industry

4-Chlorophenyl acrylate (CPA) was prepared by reacting 4-chlorophenol and acryloyl chloride in the presence of triethylamine in ethyl acetate solution. Poly(4-chlorophenyl acrylate) and copoly(4-chlorophenyl acrylate–methyl acrylate) were synthesized by the free radical polymerization in ethyl acetate at 70°C. All the polymers were characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopic techniques. The composition of the copolymers was determined by the 1H-NMR spectroscopic technique, that is, by integrating the aromatic peaks corresponding to the 4-chlorophenyl acrylate unit against the carbomethoxy group in the methyl acrylate unit. The reactivity ratios were calculated by Fineman–Ross, Kelen–Tudos (K–T), and the extended Kelen–Tudos methods. The values of r1 and r2 obtained by these methods were in close agreement with each other; that is, r1(CPA) = 0.64 and r2(MA) = 0.13 by the K–T method. The number-average molecular weight (M̄n = 1.55 × 103), the weight-average molecular weight (M̄w = 8.39 × 103), and the polydispersity index (M̄w/M̄n = 5.42) of poly(CPA) were determined by gel permeation chromatography (GPC). Thermal properties of the polymers were studied in a nitrogen atmosphere using thermogravimetric analysis (TGA). As the CPA increases in the copolymer, thermal stability of the copolymer increases (e.g., 90% weight loss occurs at 480°C for 20 mol % CPA, whereas the same weight loss occurs at 571°C for 80 mol % CPA). Acrylic binders, based on the CPA–MA–BA terpolymer, of different glass transition temperatures were prepared for applications in leather industry as top coat and base coat materials. These acrylic emulsions were cast into thin films, and their characteristics were tested for physical properties. These acrylic emulsions were applied as a base coat on leather, and the compositions having Tg values of 1.08 and 9.25°C were found to have excellent properties as base coats for leather when compared with commercial samples. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1153–1160, 1999

Synthesis and characterization of lacquers based on styrene acrylic copolymers for applications in leather industry

Radical copolymerization of styrene with butylacrylate and/or maleic anhydride was carried out at 70°C, using benzoyl peroxide as an initiator in benzene/ethylacetate in order to prepare lacquers for top coats for use in leather industry. Copoly(styrene–butylacrylate) was characterized using IR and 13C-NMR spectroscopy. Thermal properties of the polymers were studied using thermogravimetric analysis and evaluated the integral procedural decomposition temperatures of polymers. The order of reaction and the activation energy for the thermal degradation of polystyrene, poly(ST-co-MAn) and St–BA–MAn terpolymer at different temperatures were calculated. Molecular weights were determined from gel permeation chromatography and viscosity measurements. Physical properties of the films were studied and compared with standard lacquers available for top coats in leather industry.