Bovine Leather Research Articles

Development and Evaluation of the Acaricidal Activity of Xantan Gum-Based Hydrogel and Polymeric Nanoparticles Containing Achyrocline satureioides Extract.

The Rhipicephalus microplus tick causes enormous economic losses in livestock farming around the world. Despite several promising studies carried out with plant extracts such as Achyrocline satureioides against this ectoparasite, a major obstacle is related to pharmaceutical presentation forms. There is no study showing xantan gum-based hydrogel and polycaprolactone nanoparticles containing A. satureioides extract against R. microplus larvae. The objective of this study was to incorporate A. satureioides extract to develop a nanoformulation (AScn) and a hydrogel (ASlh) and evaluate them against R. microplus larvae with the purpose of increasing the contact time of the extract with the larvae and improve the effectiveness. The ethanolic extracts were incorporated in polycaprolactone nanoparticles and characterized via analysis of the mean hydrodinamic diameter and polidispersity index. The xanthan gum-based hydrogel formulation was prepared with crude extract of A. satureioides 40 mg/mL, 0.25% xanthan gum, and 8% poloxamer, to determine the bioadhesiveness of the formulation in bovine leather and the flow rate of the formulation in the animal. The results in larvae demonstrated that when evaluated in the form of a hydrogel (ASlh), mortality was higher, with 91.48% mortality at a concentration of 20 mg/mL presenting itself as an interesting alternative for controlling this ectoparasite.

Eco-Friendly Leather: Durable and Crack-Resistant Shoe Uppers By IJISRT

Today in this developing world we always want something new or an advanced product and technology. In this daily life we use shoes everyday as office wear, formalwear, casualwear, nightwear etc. It should be comfortable from inside even from outside too, it will have significant work efficiency of the product. This invention is related to development of new crack free leather for shoe upper. It may upgrade the quality of leather and also helps to resolve the finishing operation to make leather more pliable, durable, breathable and comfortable for a long time. Aqueous finishing ageing time and its durability will be increased; it could sustain the leather for a longer period. It will provide a brilliant texture as well as smooth and uniform grain structure. Also it has a tendency till a certain level to protect leather from UV rays. It will have high thermal resistance. Zinc Oxide (ZnO), the element of the bottom layer of leather serves protection from UV rays, also gives shine to the leather which can perform better bondage with collagen (protein peptide). Cowhides last very long due to their greater strength properties and it is widely available in the market due to its constant demand in the market. Cowhide a bovine leather is mostly used for shoe upper and outsole of the shoe as per its high air permeability and water permeability as well as its comfort and durability. It also maintains its shape with chrome tanned. This invention may change the quality of leather and also helps to become environmentally friendly.

A Study of the Composting Capacity of Different Kinds of Leathers, Leatherette and Alternative Materials

The leather industry is in the midst of a shift towards sustainability and circular economy principles, placing a strong emphasis on the biodegradability of its products. There has been a notable upswing in the traction gained by eco-friendly leather alternatives. Concurrently, a diverse spectrum of commercial substitutes for conventional leather has surfaced, encompassing a range from synthetic constructs like leatherette to plant-based options. The objective of this study was to evaluate the composting capabilities of genuine leather and three alternatives, namely leatherette, Piñatex®, and Desserto®, in conjunction with leather subjected to treatment with alginate derivatives. The composting evaluation was conducted in accordance with ISO standards, simulating an intensive aerobic composting process. Results revealed that bovine leather samples treated with alginate derivatives underwent complete degradation within 21 to 25 days, and conventional wet-blue production resulted in total degradation after 31 to 35 days. In contrast, vegetable-tanned bovine leather manifested initial signs of degradation after 60 days, but fell short of achieving complete disintegration even after a protracted 90-day incubation period. Alternative materials showed no degradation after the 90-day composting test, indicating a potentially lower degradation capacity compared to leather, likely attributed to the presence of non-biodegradable materials like PU and PVC, among others. The negligible degradation observed in alternative materials after 90 days of composting highlights their inferior composting performance compared to leather.

Economic efficiency of leather treated with zeolite after the pickling process

Raw bovine leather (hide) undergoes a series of manufacturing processes to obtain a finished leather or semi-finished leather, which as such can last for a long period without damage to the hide. The damage by bacteria in the tannery is almost entirely restricted to the soaking operation, but some damages occur under poor storage conditions after pickling and in a wet stage after tanning. Protection against microorganisms is still needed because long periods of storage in moisture and heat create conditions suitable for the rapid growth of microorganisms, which can cause considerable hide damage. The development of microorganisms causes damage that affects the final quality and usability of the leather. In order to avoid damage, the hide undergoes a process of washing and removing microorganisms, before the tanning process. This paper studies and compares the costs of protection from microorganisms of hide treated with bath containing zeolite and citric acid, after the process of pickling, in relation to the costs of removing microorganisms that occur due to poor storage conditions. The costs are one of the elements for determining economic efficiency. This comparison provides an insight into the costs of these processes and their cost-profitability.

Vegan leather: a sustainable reality or a marketing gimmick?

The textile industry is the only one which has utilised all kinds of resources available in nature, and the evolution of textile materials has drastically hampered nature as well. Leather and fur are a few of the classic examples of materials derived from animals that have attracted dialogues about animal rights and ethical sourcing. To substitute animal-based leather, numerous materials have been manufactured synthetically and semi-synthetically. This review article discusses various types of leather, viz., bovine leather, poromerics, leatherette, plant-based vegan leather, and the sustainable alternatives available in the market as well as at the inductive research phase. The article is a comprehensive review of the leather and its commercially available alternatives along with their marketing strategy, and technical details. The article also compiles insight into the processing, and the components of vegan leather and the environmental issues related to them. The sustainability and circularity of processing in manufacturing vegan leather have also been discussed, with biodegradability as the focal point.

Keratin Hydrolysate from Wool By-products as an Additive for Dyeing Bovine Leathers

In this research, the aim was to obtain keratin hydrolysate from wool waste from sheep breeders and use it in technologies for dyeing bovine hides. The keratin hydrolysate (KerNa), obtained by alkaline hydrolysis with sodium hydroxide, was physico-chemically analyzed, determining the protein substance in the amount of 80.65%, highlighting the bands specific to peptides and compounds with sulfur by FTIR spectroscopy and particle size by DLS technique, obtaining majority populations at 161 nm and 615 nm. Bovine hides were treated with keratin hydrolysate, in different stages of the dyeing process, and an increase in the dyeing resistance to wet and dry rubbing and the dyeing resistance to water drops was obtained, as well as the improvement of the specific color parameters. Leathers dyed with the use of the KerNa additive showed an increase in the friction resistance of the dyeing (grade 5/5) and brighter colors according to ISO Brightness. Treatments based on protein-rich keratin hydrolysate, applied in various stages of the dyeing process, interact with the leather’s collagen or tanning agents, giving the finished leathers improved properties of shade, shine and softness. The good results obtained in the applications of keratin hydrolysate in the leather industry show that the keratin extract can be the basis for obtaining new biomaterials with various applications. The utilization of wool waste from animal husbandry leads to a decrease in the amount of waste and the prevention of environmental pollution.

Antiviral leather: A functional coating based on SiO2-AgNPs to eliminate pathogens

A bovine leather material functionalized with SiO2-Ag nanoparticles (NPs) composite, which possesses highly efficient antimicrobial activity against the SARS-CoV-2 virus and Staphylococcus aureus (S. aureus) bacteria, has been developed. The characterization of this material was conducted using scanning and transmission electron microscopy (SEM and TEM), energy dispersive X-ray spectrometry (EDS), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and x-ray photoelectron spectroscopy (XPS). The immobilization of SiO2-AgNPs within the collagen fibers of the leather resulted in surface modification, leading to an increase in material roughness (from 8.93 nm ± 1.55–12.36 nm ± 1.76 nm) and the contact angle (from 76° to 81°) of the SiO2-AgNPs coated leather. This functionalized leather exhibited an impressive efficacy of 99.93% against SARS-CoV-2% and 99.99% against S. aureus, attributed to the oxidizing properties of the Ag NPs and the enhanced production of reactive oxygen species (ROS). These results highlight that the immobilization of SiO2-AgNPs on the surface of bovine leather is an simple, effective and low-cost strategy for obtaining new surfaces with high antimicrobial activity.

Study of some Functional Properties of Elastin Extracted from Bovine Leather

The study aimed to detect elastin protein extracted from leftover bovine leather that is not used in other industries, by conducting some tests to identify this protein and its functional properties and the possibility of using it in scientific applications, as the chemical composition tests showed that it contains a high percentage of protein and low percentages of moisture, fat and ash, and some functional properties were conducted to find out the ability of elastin to bind water and oil compared to other studies, studying the structural and chemical characterization of the properties of elastin extracted by FTIR and amide groups extended to elastin, as the results of electron microscopy (SEM) revealed, the shape of elastin fibers showed that they have a structure similar to myofibrillar muscle fibers, except that they are coarser, asymmetric, and have an asymmetric extension, while the TGA test showed that elastin extracted from bovine leather has 5 peaks and fracture peaks for weight loss in percentage as a function of temperature and that elastin gets a weight loss of up to and 44.02% at a temperature of 600 C, while it was shown DSC calorimeter analysis It can withstand a temperature of up to 290 °C.

Thermal characterization of leathers tanned by metal salts and vegetable tannins

In this work, the thermal properties of vegetable (mimosa), metal salt (chromium) and mixed (chromium-mimosa and aluminum-myrobalan) tanned bovine leathers were studied to understand the thermal decomposition processes with the aim of possible utilization of various leather wastes by thermal conversion. Thermogravimetry/mass spectrometry (TG/MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) measurements were carried out to compare the thermal behavior and reveal interactions between the leather and various tannins. Bovine parchment was used as an untanned reference material. The tanning agent ratios were estimated by determination of ash, nitrogen and protein contents of the samples. It was found that ash yield is a good indicator for the inorganic content, while the protein content is inversely proportional to the total tannin content in leathers. The thermal decomposition of the samples as a function of the temperature was performed using TG/MS. The differences between the samples are clearly recognizable on the thermogravimetric curves and the mass spectrometric evolution profiles of the products. Among the tanning agents, chromium had the largest impact on the thermal decomposition process. Therefore, additional TG/MS experiments were carried out on chromium-treated parchment samples and the catalytic effect of chromium was demonstrated on the evolution curves of several products. It was established that hydrolysis of the amide bonds of the polypeptide chain was retarded resulting in less ammonia formation, and higher yield of water. On the other hand, higher amounts of hydrogen cyanide and other nitriles were released in the presence of chromium sulfate. The decomposing chromium sulfate released oxygen beside sulfur dioxide, which dehydrogenated certain amino acid residues leading to the enhanced formation of nitriles and water. The volatile compounds of the decomposition were determined by Py-GC/MS at 400 and 600 °C. The diketopiperazines (DKPs) dominated the pyrograms at both temperatures, but the ratio of gaseous and other products of smaller molecular mass was increased at higher pyrolysis temperature and in the presence of metal tanning agents. The chromium-treated parchment samples were also studied by Py-GC/MS. The relationship between the chromium content and the formation of certain decomposition products has been confirmed. Principal component analysis (PCA) was performed using the Py-GC/MS data of leathers and parchment. The PCA results show clear separation between the chromium-tanned, vegetable-tanned and mix-tanned leathers as well as parchment.

Application of Leather Waste Fractions and Their Biochars as Organic Fertilisers for Ryegrass Growth: Agri-Environmental Aspects and Plants Response Modelling

The automotive upholstery industry, which processes bovine leathers, has struggled with vast amounts of solid waste, of which the majority are fractions, such as shavings and splits and offcuts, both containing chromium (Cr) and free of Cr. In this work, a novel leather waste-to-fertiliser approach has been tested: four lightly processed (incubation with effective microorganisms) and three aggressively processed (using pyrolysis or hydrolysis processes) tanned leather waste fractions were used. They were applied as organic nitrogen-based fertilisers in two separate glasshouse experiments, consisting of four subsequent harvests, under spring–autumn conditions in northern Poland. The Cr stressing effect caused by bovine shavings containing Cr and splits and offcuts containing Cr stimulated an increase in ryegrass growth after 30 days, providing twice the dry matter yield than bovine shavings free of Cr and splits and offcuts free of Cr, then (after 90 and 120 days) it inhibited growth. The Monod kinetics model was developed using the best fitting procedure (R2 > 0.94) for the efficiency of internal N use in ryegrass for the lightly processed fractions of tanned leather-waste fractions and each harvest. In the case of the processed leather waste-fractions, the relation was quasi linear, evidencing less growth inhibition and no over-fertilisation effects. The acid hydrolysate of bovine shavings containing Cr showed the best performance, reaching a relative agronomic effectiveness (RAE, N utilization-based) equal to 89%, 95%, 19%, and 38% for 30, 60, 90, and 120 days, respectively, and 71% in total. For the lightly processed fractions, it was lower than 12%. The future perspective should focus on steps including scaling up the tests to field conditions; transportation, storage, and application methods; effectiveness for other crops; usage in crop rotation systems; environmental impact assessment; production carbon footprint; commercial potential; and optimizing the production processes.

Thermal, Acoustic, and Hygrothermal Properties of Recycled Bovine Leather Cutting Waste-Based Panels with Different Compositions

This study aims to investigate the thermo-acoustic and hygrothermal properties of innovative panels made of leather waste produced by a bag factory from a circular economy perspective. Their performance was compared with other residual-based insulation panels. The leather scraps were chipped and three boards were fabricated by means of a mold with different compositions, adding adhesive glue. In order to improve the sustainability aspects, a sample was assembled by using a water-based polyurethane glue, in addition to the two panels with vinyl glue. Panels were tested for thermal, acoustic, and hygrothermal performance. Thermal conductivity values in the range of 0.064–0.078 W/mK at 10 °C were measured depending on the composition and the adhesive. A slight thermal performance deterioration occurs when using the natural water-based glue. The samples were characterized by good performance both in terms of sound absorption coefficient (Noise Reduction Coefficient NRC = 0.21–0.28) and Transmission Loss, up to 59 dB values. Water vapor resistance factor values in the 35–48 range were obtained, close to the values of standard materials, such as expanded polystyrene and polyurethane.

Life cycle assessment of MycoWorks’ Reishi™: the first low-carbon and biodegradable alternative leather

BackgroundOver the past few years, several alternative leather technologies have emerged and promise advantages over incumbent leathers with respect to sustainability despite most containing enough plastic to prevent safe and effective biodegradation. Of the alternative leathers in production or advanced development, few fit the dual criteria of low-carbon and near-zero plastic. Reishi™ is a leather alternative, grown using MycoWorks’ Fine Mycelium™ technology, with less than 1% polymer content and satisfies the same performance, quality, and hand feel as animal leather. We present here the first Life Cycle Assessment (LCA) of Reishi™, detailing its “cradle-to-gate” carbon footprint and broader environmental profile. The pilot- and full-scale production of 1 m2 of post-processed, finished, and packaged Reishi™ both before and after production improvement implementations is modeled, and the environmental footprint impact assessment method is performed.ResultsIt was found that Reishi’s™ carbon footprint is as low as 2.76 kg CO2-eq per m2, or 8% of the value of the bovine leather benchmark modeled. Furthermore, it was found that Reishi™ has a lower impact compared to bovine leather modeled across a number of impact categories, including eutrophication, ecotoxicity, human health effects, and others. Reishi’s™ impact “hotspots” were determined, with the largest opportunity for further reduction being improved energy efficiency in the growth of mycelium, in particular, the process’s sterilization of raw material inputs via autoclave tools. It is also shown that MycoWorks’ passive process for growing mycelium has a carbon footprint two orders of magnitude lower than incumbent mycelium growth processes that actively consume carbon dioxide gas, which MycoWorks’ process does not require.ConclusionsReishi™ is shown to be a promising sustainable material through its unique combination of natural quality, low-carbon footprint as determined by this LCA, and biodegradability due to its lack of plastic or crosslinked content. Its manufacturing process is low impact even when produced at a scale of tens of thousands of square meters per year—a miniscule fraction of the billions of square meters of bovine leather already sold per year. With further use of this leather alternative, additional efficiency gains are likely to be realized.

Impact of the pre-slaughter period on the contamination of bovine leather and the operational sanitary procedure for skinning on the quality and microbiological safety of the carcass

Sanitary procedures are essential in cattle slaughter processes to minimize microbiological hazards from meat consumption. This study aimed to verify the influence of the pre-slaughter period and the correct execution of the operational sanitary procedure (OSP) for skinning in the breast region on the counts of indicator microorganisms and the occurrence of enteropathogens in the hides and carcasses of cattle. Forty-eight animals were evaluated and divided into 12 clusters, half of which were allowed 13 h of preslaughter rest, while the other half were allowed 23 h of pre-slaughter rest. The presence of microbiological indicators, including Salmonella spp., Listeria spp., and Shiga toxin-producing (STEC), enteropathogenic (EPEC), and enterohemorrhagic (EHEC) Escherichia coli, were evaluated in superficial samples of leather and carcass in which the OSP for skinning of the chest was performed either correctly or incorrectly. There was no significant effect (p > 0.05) of the pre-slaughter period on the counts of total coliforms, E. coli, enterobacteria, and mesophilic aerobics in the hide or carcass, although, in the carcasses, this difference was 93.4% for mesophilic aerobics and enterobacteria in the group of animals subjected to 23 h of rest compared to those subjected to 13 h of rest. Regarding the correct execution of the skinning OSP, there was also no significant effect (p > 0.05) on the indicator quantifications, but in relation to the presence of enteropathogens, it was possible to proportionally identify more EPEC and STEC in carcasses subjected to the wrong OSP, as it was only possible to identify Salmonella spp. and EHEC in carcasses subjected to the wrong OSP. The correct execution of the OSP for skinning incision in the chest region of the animal reduced the microbiological risk of the carcasses for the presence of enteropathogens and facilitated compliance with the microbiological standards for the carcass.

Application of L-Ascorbic Acid as an Antioxidative Colorment in Leather Finishing

In this study, chrome tanned bovine crust leathers were dyed white during finishing process. Experiments with 1%, 2%, 3%, 4% and 5% L-ascorbic acid addition were performed on the finishing layer of the finishing application. L-ascorbic acid was not added to the control group and processed according to the standard method. After these processes, color measurement analyzes were performed on Konica Minolta CM 3600d spectrophotometer. In order to investigate the effects of L-ascorbic acid on other performance properties of leather, light fastness test according to TS 1008 EN ISO 105-B02 (2001 TS EN ISO 11640 2001) and dry rub fastness test according to standard method were performed. The results of the study were statistically evaluated according to the NCSS (Number Cruncher Statistical System) method. As a result of the research, it was observed that L-ascorbic acid gave a pearly pink color to the leathers. It was found that the dry rubbing fastness of the leathers treated with L-ascorbic acid improved. In the light fastness tests, the results of the experimental group leathers were recorded better by the blue scale.

Thermophysiological properties of bovine leather in dependence on the sampling point, tanning and finishing agents

The influence of differently tanned and finished bovine leather on thermophysiological properties was investigated. In addition, it was investigated whether sampling has a significant influence on the thermophysiological properties. The back of the tested leathers is thicker than the neck because of better microstructure regularity and uniformity as well as thicker and denser distributed fibrils than in the neck parts. The neck parts have a greater proportion of air-filled spaces between the fibrils, resulting in a higher thermal resistance of the leather neck parts. Considering the thickness of synthetic and chrome-tanned leathers (dyed and hydrophobized), the thinner chrome-tanned leathers (0.063 W m−1 °C−1 for the neck part, 0.090 W m−1 °C−1 for the back part part) have almost the same thermal conductivity as synthetic ones (0.065 W m−1 °C−1 for the neck part, 0.089 W m−1 °C−1 for the back part). Their thermal and water vapour resistance show considerable differences. There is no significant difference in water vapour resistance of the neck and back part of chrome tanned, dyed and hydrophobized leather (25.27 m2 Pa W−1 for the neck part; 25.15 m2 Pa W−1 for the back part) in contrast to equally treated synthetically tanned leather (30.38 m2 Pa W−1 for the neck part; 26.96 m2 Pa W−1 for the back part).The presented study could help in choosing the appropriate point of sampling, tanning as well as finishing agents for obtaining satisfying thermophysiological comfort in the wide range of leather application.

Deforestation as a Systemic Risk: The Case of Brazilian Bovine Leather

Tropical deforestation and forest degradation driven by agricultural commodity production remains one of the important sustainability challenges of our times. The responses to tropical deforestation so far have not managed to reverse global trends of forest loss, reigniting the discussion about more robust and systemic measures. The concept of deforestation risk is highly relevant for current debates about policy and trade, and likely to increase in importance in the context of the proposed EU Regulation on Deforestation-free Products and EU-Mercosur Trade Agreement. We argue that deforestation is a systemic risk that permeates through different economic sectors, including production, manufacturing, service and control sectors. International trade, investment and economic policies thus act as a systemic trap that cause the production sector to continue with nature’s destruction. This article seeks to more clearly define deforestation risk and uses the case of bovine leather from Brazil to illustrate how pressures for deforestation accumulate across economic sectors towards production, while deforestation risk is dispersed in an opposite trajectory. The article draws on multiple datasets and an extensive literature review. Included are quantitative data sources on annual slaughter, bovine hide/leather registry and annual deforestation, slaughterhouse and tannery locations. We argue that the EU banning unsustainable products from entry and putting incentives for more sustainable agricultural production in the tropics addresses deforestation risks that are currently visible and relatively easy to identify. These response mechanisms are conditioned upon traceability of deforestation risk across supply chains, which is prone to falsifications, leakage and laundry. Although proven to be essential, the proposed EU responses still miss out deeper leverage points to address the systemic drivers of deforestation coming from the manufacturing, service and control sectors that make production through deforestation profitable in the first place.

The Effect of Polymethylsilsesquioxane Concentration on the Liquid Foundation: Characterization of Nanostructure and Biophysical Properties

Aims: Polymethylsilsesquioxane (PMQS) is a silicone derivative that serves as a skin conditioning agent and moisturizer in cosmetics. The objective of this study is to identify the effect of different concentrations PMSQ (0.12, 0.20 and 0.35 wt %) on liquid foundation (LF) and find the optimized composition in vitro.
 Study Design: Structural and morphological features of the examined nano/micro-sized samples were investigated by different methods.
 Place and Duration of Study: Hacettepe University, Department of Physics Engineering, X-Rays Laboratory, between September 2017 and September 2019.
 Methodology: Micro/nano scale structural and morphological properties of samples were investigated by means of a multi-methodological approach based on Small‐ and/or Wide‐Angle X‐ray Scattering (SWAXS), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDX), Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) Spectroscopy and UV-vis Spectroscopy. The LF (control) and PMSQ-LF films at one-week intervals for 4 weeks, and bovine leather coated samples with LF and PMSQ-LF were also investigated by SWAXS. The effect of PMSQ on biofilm formation activity in E. coli and S. aureus were also examined.
 Results: The most significant finding of this study is that even the low concentration of polymer in LF showed differences in nano structure and it was found that a decrease in biofilm formation. Nano formation becomes more pronounced, and the number of agglomerations decreases after 4 weeks. The reason for the study over a 4-week period was the desire to take into account the independent effect of each LF use, as well as the periodic stacking and diffusing effect that will occur in the depths of the skin over time. In the UVA range (320-400 nm) lower transmittance values were found for LF and PMSQ - LF films. 
 Conclusion: The results suggest that optimum polymer concentration in liquid foundation should be considered as a main step. The smart and systematic use of polymer additives is directly manifested in the nanoscopic structure and can improve the harmful UV rays prevention properties, which are important for health as well as cosmetic effects for beauty purposes.

Analysis of variation of the skin substance with the application of different acids in the pickle stage in Ecuadorian serrano bovine leathers

A chemical analysis was carried out to determine the content of skin substance in different leather samples prepared using several acids in the pickling stage. Ecuadorian bovine skin was utilized. It went through the tanning processes until reaching the pickling stage in which three treatments employing sulfuric acid, formic acid and oxalic acid, respectively, were applied. Later, tanning was applied, wet blue samples were obtained and their contents of skin substance were measured by means of AST D2868-17 rules. Results were verified through a statistical analysis using Infostat software. After post tanning stages a dyed leather was obtained upon which physical tests of tension resistance, elongation percent and lastometry as well as sensorial essays of feeling, softness and swelling were executed. The treatments produce results of skin substance from every leather area, that is, head, loin and backside. It is found that the sulfuric acid pickling features the highest content of skin substance (72.63%) followed by the formic acid pickling (70.94%) and the oxalic acid pickling which has the lowest amount of skin substance (65.04%). In order to validate the results, a statistical analysis was performed which confirms the chemical analysis. To ratify which one was the best treatment, a comparison based on the properties of each acid was made. The formic acid was confirmed as the most appropriate since it differentiates from the sulfuric acid due to the skin substance content by complying with the required parameters of elongation (15.89%), and softness/swelling (4%). On the other hand, oxalic acid produced lesser quality results.

Investigation of some factors from the technological processing of leather for upholstery of car seats on their flammability

Natural leather is widely used for car upholstery and has a non-flammability requirement. In the present work, bovine leather intended for upholstery for car seats are studied. Various technological schemes of tanning have been applied, including combined; various finishing methods have been applied and two flame retardants have been used, namely Firex LFS and Flacavon B-45. It was found that the studied methods of combined tanning of investigated leathers do not affect the colour fastness to dry and wet rubbing, but the highest total flame combustion time of the source is given by aluminium-chromium re-tanned leathers and this indicator decreases depending on the type of re-tanning of the tested samples in the following order: chrome, aluminium, vegetable. Flacavon B-45 showed higher efficiency in terms of flame retardancy of the investigated leathers.

Influence Modeling and optimization of sulphide removal by catalytic oxidation of tannery fur effluents [Modelamiento y optimización de la remoción de sulfuros por oxidación catalítica de efluentes de pelambre de curtiduría

The residual effluents from the fur stage of the bovine leather tannery industry are characterized by having a high concentration of sulfides. The objective of this study was to evaluate the effects of aeration time and pH in the residual effluents of the leather stage of the tannery, with the catalysts MnO2 and MnSO4 separately; as well as, determine adjustment models through the response surface methodology and the optimal intervals of the best conditions that lead to a higher percentage of sulfide removal. For this reason, the sulphide removal percentage was evaluated from samples extracted from the pellet stage, by means of catalytic oxidation treatments; varying the catalyst, pH and aeration time. The catalysts used were manganese dioxide (MnO2) and manganese sulfate (MnSO4) and for each catalyst the pH was varied in the values ​​of 8.5; 9.5; 10.2 and 13.4; likewise, the aeration time was varied in the values ​​of 30, 60, 90, 120, 150, 180, 210 and 240 minutes. 64 treatments were carried out, with 3 repetitions each, reporting the average values ​​of the sulfide removal percentage. The response surface methodology was used to adjust the correlation of the variables to a quadratic model; Likewise, through contour graphs the regions with the highest percentage of sulfide removal were easily identified and by superimposing contour graphs the optimal ranges of the variables pH and aeration time were determined for removal percentages greater than 98%. Based on this evaluation, it is proposed for treatments with manganese dioxide, aeration times between 160 to 240 min and pH between 8.5 to 9 and for treatments with manganese sulfate, aeration times between 110 to 240 min and pH between 8.5 to 9.8. The coefficients of multiple determination R2 for the models with catalyst MnO2 and MnSO4 were 97.51% and 95.12% respectively. With the MnSO4 catalyst, higher removal percentages were achieved at a shorter aeration time, compared to the treatments carried out with the MnO2 catalyst.