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Novel blades for shaving - a new approach to understanding the shaving process (#242)
P. Küchler1, T. Witt2, A. Nikowski2, E. Klüver3, M. Meyer3
1 Heusch GmbH, Aachen, Germany
The shaving process is one of the most important steps in leather production. However, the underlying principles and mechanisms are not yet fully understood. Generally, the successful performance of the shaving process is based on long-time experience, and the tanneries rather optimize the preceding process steps than change the shaving parameters. In a current research project the research partners (Heusch GmbH, TU Dresden and FILK gGmbH) have united their expertise in order to understand the interaction between the shaving blade and the semi-finished leather (wet-blue or wet-white). The objective of the project is to gain more insight into the physics of shaving and to create a background of knowledge, which will be the technical base for developing novel and more effective shaving blades.
Heusch presents the advantages of a novel serrated shaving blade. In comparison with the standard design an serrated blade yields higher shaving accuracy and uniform thickness of the hides. Stretching forces along the dorsal line of the hides are reduced, which avoids structural damage. Marginal hide regions are less frayed, thus increasing the usable surface area. The small size and compact form of the shavings are advantageous for recycling and disposal. Exploiting these advantages combined with an optimized grinding process, the user can increase the lifetime of the serrated blades. Based on these experiences there is an urgent need to thoroughly understand the physical cutting processes which take place during the shaving step.
In the current research project an experimental test station is designed which is intended to simulate the shaving process in a simplified setting as a cutting procedure of a blade into a leather surface. This test station will enable the variation of material, geometry and configuration of the blade as well as the measurement of forces emerging during cutting at the blade and the leather surface, which emerge during cutting. The registered data shall provide information on the question, how the cutting forces depend on technological parameters, like blade material, geometry, configuration, cutting speed, leather moisture or tanning method. Based on the knowledge of these relationships novel, even more effective shaving blades can be developed. In a second approach the cutting process of a single leather fibre will be simulated virtually on a microscale level. The goal is the understanding of the interaction of a moving metal blade with a flexible, unilaterally fixed leather fibre. The simulation is supposed to yield data on cutting speed and fibre behaviour under conditions which are experimentally difficult to access.
The physical basics of the shaving process are not yet fully understood.
The presented research project aims at the understanding of the interaction between shaving blade and leather fibres during the shaving process.
The approach in the project is to model the cutting procedure in a simplified experimental test station and in a computational simulation model.
Keywords: shaving process, shaving blade, process simulation
Automation in Leather Making – A Cleaner Production Approach (#271)
R. C. Panda1, J. Kanagaraj2
1 CSIR-CLRI, Chemical Engg, Chennai, India
In most of the tanneries, water and chemicals are added manually in the tanning drum and pH of the float / leather is adjusted. Addition of correct amount of process recipe are necessary for better processing of the hides and minimizing wastage of utility, thereby controlling pollution load in effluent. However, fugitive-emission from process and drains accumulate ammonia, hydrogen-sulphide and volatile organic compounds which contribute bad odor in tannery as well as in wastewater-treatment premises causing problems to occupational health & safety of workers. Both local and supervisory control stations are employed to monitor and accurately manage the unit operations. The objective of this work is to produce consistent quality of leathers and to provide a healthy environment through automatic dosing and odor abatement system. Therefore the entire process control operation is integrated to operate through PLCs with following five modules:
i) Water addition module ii) Chemical preparation and dosing system iii) pH monitoring and float recycle system iv) Drum rotation module v) Odor reduction module.
In the integrated system, critical and bulk chemicals are stored in bulk storage tanks and are drawn into the load cell (LC) as per process sequence or recipe for feeding into the drums through auxiliary tanks. The float-recycle system helps to remix & heat the float where a pH electrode is housed to monitor pH online. The pH monitoring system adjusts addition of critical chemicals that indicates automatic end point.
The contaminated air inside the tannery is sucked and passed through blower and then through bio-filter. The filtration process is based on the principle that VOCs (in the order of 50-200 ppm) and odors can be biologically treated by naturally occurring microbes. The control parameters monitored are: moisture in the bed and uniformity of media (contaminated air or process liquor). The humidity and temperature of inlet media is controlled and contact time with microbes is 10-30 secs. Moisture is controlled to maintain microbial population.
A lead in laboratory scale has been developed to measure process variables (PV) considering their spatial distribution in two dimensions. Spatial distribution of process variables inside hides (across cross section) may provide accurate measurement of through reconstruction of image and data driven models using artificial intelligence tools. Computational intelligence is developed for updation of model parameters as that can be used for direct estimation of PV
1. Cleaner production is provided through automation of dosing & pH monitoring using PLC in indegeneous way
2. Pollution Load in exit stream and odor-gas emmision are minimized
3. Artificial Intelligence and data analytics techniques are used in Leather making
Keywords: dosing system, odor-control, AI based modeling
Synthesis and Application of Dendritic-linear Polymer PAMAM-Si for Leather Fatliquoring Process (#120)
X. Wang1, S. Sun1, H. Wang2, J. Li2
1 Shaanxi University of Science & Technology, College of Chemistry and Chemical Engineering, Xi’an, China
Environmental pollution caused by leather making is the primary concern in the development of leather industry. The use of safe, effective and multi-functional green chemical products has the advantages of reducing leather operations, increasing chemicals utilization, decreasing the environmental burden, improving leather quality. In this study, dendritic-linear polymers of PAMAM-Si 1G and PAMAM-Si 2G were applied to fatliquoring process, which were prepared by branching polysiloxane on the dendritic polyamide-amine (PAMAM). Then the emulsion properties, fatliquoring properties and fatliquoring mechanism were studied by EDS, SEM, XRD, TG and washing experiments. The conclusion was drawn that PAMAM-Si are weak alkali products with high emulsion stability. The particle size of PAMAM-Si 1G was 35.8 nm, and that of PAMAM-Si 2G was 26.7 nm. They can improve the softness, shrinkage temperature and physical and mechanical properties of leather. The softness of leather with PAMAM-Si 1G and PAMAM-Si 2G increased by 115.6% and 104.7% respectively. The shrinkage temperature of leather with PAMAM-Si 2G increased by 2.9℃. The Breaking elongation of leather with PAMAM-Si 1G and PAMAM-Si 2G increased by 38.6% and 32.4% respectively. At the same time, PAMAM-Si not only increased the distance and disorder of fiber but combined with collagen fiber through hydrogen bond, a certain amount of physical adsorption and covalent bond.
1. The dendritic-linear polymers of PAMAM-Si 1G and PAMAM-Si 2G were prepared by branching polysiloxane on the dendritic polyamide-amine (PAMAM).
2. PAMAM-Si can improve the softness, shrinkage temperature and physical and mechanical properties of leather.
3. PAMAM-Si not only increased the distance and disorder of fiber but combined with collagen fiber through hydrogen bond, a certain amount of physical adsorption and covalent bond.
Keywords: Polysiloxane, PAMAM, dendritic-linear, fatliquor, mechanism
Synthesis of Cationic Protein with High Quaternary Ammonium Coefficent for Adsorption Dyes Application in Leather Retanning (#150)
J. Xu1, J. M. Lu1, T. D. Li1
1 Qilu University of Technology, Shandong Provincial Key Laboratory of Molecular Engineering, Taishan scholars team, Jinan, China
The presence and toxic effect of pollutants in water bodies have been identified as a global challenge.1-2 The removal of high chroma of leather wastewater is a focused problem. In the work, a cationic protein with high quaternary ammonium coefficent was synthesized, which presented excellent adsorption ability for conventional dyes used in the tanning process (Figure 1). Firstly, tetramethylethylenediamine and epichlorohydrin were used to synthesize difunctional epoxy quaternary ammonium salt. Then, the chemical modification of gelatin through grafting reactions between free -NH2 groups and epoxy quaternary ammonium salt was performed in an aqueous medium to obtain cationic protein. The results of adsorption experiment of cationic protein indicate that rapid and complete adsorptions were displayed for direct purple N and acid black, which is attributed to the conjugated structure of them. The cationic protein also exhibited remarkable efficiency in removing acid red, acid golden G, acid lake blue A, acid green and acid orange II, and 90% removal rates were achieved within 30 minutes. Adsorptional kinetic experimental data showed that the pseudo-second-order model3 and the intramolecular diffusion model3 fitted well with the adsorption of acid orange II, indicating that the chemical interaction between adsorbate and adsorbent is the rate controlling step. 1% acid orange II was used to retanning. The result showed that the concentration of acid orange II in the wastewater decreased to 0.05% and the product of tanned leather including the cationic protein presented bright color.
1. M.F. Akhtar, M. Ashraf, A. Javeed, A.A. Anjum, A. Sharif, A. Saleem, B. Akhtar, A.M. Khan, I. Altaf. Toxicity Appraisal of Untreated Dyeing Industry Wastewater Based on Chemical Characterization and Short Term Bioassays. Bulletin of Environmental Contamination & Toxicology 96 (2016) 502.
2. A. Ali Shaikh, B. Rachman Ihsan, A. Saleh. Tawfik. Simultaneous trapping of Cr(III) and organic dyes by a pH-responsive resin containing zwitterionic aminomethylphosphonate ligands and hydrophobic pendants. Chem. Eng. J. 330 (2017) 845.
3. H. Ma, S.Y. Pu, Y.Q. Hou, R. X. Zhu, A. Zinchenko, W. Chu. A Highly Efficient Magnetic Chitosan “Fluid” Adsorbent with a High Capacity & Fast Adsorption Kinetics for Dyeing Wastewater Purification. Chem. Eng. J. 345 (2018) 556.
1. In the work, a cationic protein with high quaternary ammonium coefficent was synthesized.
2. The results of adsorption experiment of cationic protein indicate that rapid and complete adsorptions were displayed for direct purple N and acid black, which was attributed to the conjugated structure of them. The cationic protein also exhibited remarkable efficiency in removing acid red, acid golden G, acid lake blue A, acid green and acid orange II, and 90% removal rates were achieved within 30 minutes. Adsorptional kinetic experimental data showed that the pseudo-second-order model and the intramolecular diffusion model fitted well with the adsorption of acid orange II, indicating that the chemical interaction between adsorbate and adsorbent was the rate controlling step.
3. 1% acid orange II was used to retanning. The result showed that the concentration of acid orange II in the wastewater decreased to 0.05% and the product of tanned leather including the cationic protein presented bright color.
Graphical abstract. The cationic protein with high quaternary ammonium coefficent presented excellent adsorption ability for conventional dyes used in the tanning process. Rapid and complete adsorptions were displayed for direct purple N and acid black. 90% removal rates were achieved within 30 minutes for acid red, acid golden G, acid lake blue A, acid green and acid orange II.
Keywords: Cationic protein, High quaternary ammonium coefficent, Adsorption dyes, Leather retanning
Mesoporous Hollow SiO2 Spheres Stabilized Pickering Emulsion to Improve Water Vapor Permeability and Water Resistance for Leather Finishing Agent (#199)
Y. Bao1, 3, Y. Zhang1, 2, J. Ma1, 3
1 Shaanxi University of Science and Technolog, College of Bioresources Chemical and Materials Engineering,, Xi'an, China
In order to solve the negative impact of coating on water vapor permeability of leather and overcome the poor water resistance of polyacrylate leather finishing agent, it was proposed that the mesoporous SiO2 spheres with hollow structure instead of traditional surfactant were introduced into polyacrylate by Pickering emulsion polymerization. It was expected to increase the water vapor permeability of polyacrylate film by increasing the path and shortening the route of water vapor molecules through the film, and improve the water resistance of film by avoiding the use of surfactant.
Hence, stable Pickering emulsion stabilized by mesoporous hollow SiO2 spheres was prepared and its stability was investigated by Turbiscan Lab in this paper. Water vapor permeability, water uptake and mechanical property of polyacrylate film were also studied. Compared with emulsion stabilized by surfactant, Pickering emulsion indicated excellent stability with lower TSI value of 0.5. Contrasted with polyacrylate film with SDS, the introduction of mesoporous hollow SiO2 spheres can improve the water vapor permeability of polyacrylate film. Meanwhile, water absorption measurements showed that the water absorption ratio of the film with mesoporous hollow SiO2 spheres decreased from 112.34 to 40.84%, possessing the ideal ability to water resistance of polyacrylate film. Its film with mesoporous hollow SiO2 spheres also revealed increases of up to 188% in tensile strength and 41.15% in elongation at break. This study can provide a theoretical foundation for designing and synthesizing leather finishing agent with excellent stability, water vapor permeability and water resistance synchronously.
1. Mesoporous hollow SiO2 spheres stabilized Pickering emulsion exhibits outstanding stability.
2. The introduction of mesoporous hollow SiO2 spheres can improve the water vapor permeability of polyacrylate membrane.
3. Polyacrylate membrane shows excellent water resistance.
Keywords: Pickering emulsions, mesoporous hollow SiO2 spheres, stability, water vapor permeability, water resistance