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At least 19 recordsLinked to original sources
PubMed2004

Natural leathers from natural materials: progressing toward a new arena in leather processing.

Globally, the leather industry is currently undergoing radical transformation due to pollution and discharge legislations. Thus, the leather industry is pressurized to look for cleaner options for processing the raw hides and skins. Conventional methods of pre-tanning, tanning and post-tanning processes are known to contribute more than 98% of the total pollution load from the leather processing. The conventional method of the tanning process involves the "do-undo" principle. Furthermore, the conventional methods employed in leather processing subject the skin/ hide to a wide variation in pH (2.8-13.0). This results in the emission of huge amounts of pollution loads such as BOD, COD, TDS, TS, sulfates, chlorides and chromium. In the approach illustrated here, the hair and flesh removal as well as fiber opening have been achieved using biocatalysts at pH 8.0, pickle-free natural tanning employing vegetable tannins, and post-tanning using environmentally friendly chemicals. Hence, this process involves dehairing, fiber opening, and pickle-free natural tanning followed by ecofriendly post-tanning. It has been found that the extent of hair removal and opening up of fiber bundles is comparable to that of conventionally processed leathers. This has been substantiated through scanning electron microscopic analysis and softness measurements. Performance of the leathers is shown to be on par with conventionally chrome-tanned leathers through physical and hand evaluation. The process also exhibits zero metal (chromium) discharge and significant reduction in BOD, COD, TDS, and TS loads by 83, 69, 96, and 96%, respectively. Furthermore, the developed process seems to be economically viable.

Animals↗
PubMed2006

Reversing the conventional leather processing sequence for cleaner leather production.

Conventional leather processing generally involves a combination of single and multistep processes that employs as well as expels various biological, inorganic, and organic materials. It involves nearly 14-15 steps and discharges a huge amount of pollutants. This is primarily due to the fact that conventional leather processing employs a "do-undo" process logic. In this study, the conventional leather processing steps have been reversed to overcome the problems associated with the conventional method. The charges of the skin matrix and of the chemicals and pH profiles of the process have been judiciously used for reversing the process steps. This reversed process eventually avoids several acidification and basification/neutralization steps used in conventional leather processing. The developed process has been validated through various analyses such as chromium content, shrinkage temperature, softness measurements, scanning electron microscopy, and physical testing of the leathers. Further, the performance of the leathers is shown to be on par with conventionally processed leathers through bulk property evaluation. The process enjoys a significant reduction in COD and TS by 53 and 79%, respectively. Water consumption and discharge is reduced by 65 and 64%, respectively. Also, the process benefits from significant reduction in chemicals, time, power, and cost compared to the conventional process.

Animals↗
PubMed1998

Speciation of chromium in tanned leather gloves and relapse of chromium allergy from tanned leather samples.

There are concerns that wearing chromium tanned leather gloves can provoke a lapse of hand dermatitis in chromium sensitive patients. Various forms of chromium have different biological effects and the determination of total chromium (both soluble and insoluble), which often is used in clinical studies, may therefore not be an adequate measure of the adverse exposure. However, investigations, where dissolution of hexavalent chromium from leather gloves has been experimentally studied, could not been found in the literature. The aim of this pilot study was therefore to determine the total amount of chromium and the amount of sweat leachable chromium in different leather glove materials and also to apply samples of these materials in a patch test to chromium sensitive patients to see if they could provoke a reaction. The results showed tha chromium tanned leather contained about 3% (m/m) chromium. Chromium can also be found in dyed vegetable tanned leather, probably emanating from the leather dye. Small amounts (average 0.08% m/m) of leachable hexavalent chromium were found in both chromium and vegetable tanned leathers. Thus, the risk of relapse of chromium dermatitis cannot be disregarded and further studies on the causes of relapse of chromium dermatitis are necessary.

Chromium↗
PubMedDate not supplied

Cancer risks associated with employment in the leather and leather products industry.

A recent study of relationships between occupation and cancer at Roswell Memorial Institute, Buffalo, New York, identified significantly high risks of bladder among men and women with a history of employment in plants manufacturing leather and leather products. Among males, the relative risk increased with duration of employment and remained elevated after adjustment for smoking habits. Among male leatherworkers, significantly increased risks were seen for cancers of the buccal cavity and pharynx and larynx that could not be explained by differences in smoking habits. Malignant lymphomas were also associated with elevated risks among men and women who had worked in the leather industry. Review of processes and agents found in leather manufacture reveals several areas with exposure to potentially carcinogenic materials, including azo and other synthetic dyes that have induced cancer in laboratory animals. Further studies of person employed in the leathermaking and fabrication industries seem advisable to characterize the nature of exposure-response relationships.

Female↗
PubMed1999

[Determination of pentachlorophenol residues in textiles and leather and leather products by gas chromatography/mass spectrometry].

A method for determination of pentachlorophenol residues in textiles and leather and leather products by gas chromatography/mass spectrometry was developed. The pentachlorophenol residues in samples was acidified with sulphuric acid solution (6 mol/L) and extracted with n-hexane. After the n-hexane layer was washed with sodium sulphate solution (20 g/L)until it was clear, determination was made by means of a gas chromatograph equipped with MSD, using external standard method. A DB-17 fused silica capillary column (30 m x 0.25 mm i.d.; 0.25 micron film thickness) was employed in the analysis, The column temperature program included a 2 min isothermal period at 50 degrees C, temperature increased at a rate of 30 degrees C/min to 220 degrees C, and hold for 1 min; temperature increased of at a rate 6 degrees C/min to 260 degrees C, and hold for 1 min. Mass spectra were obtained by electron impact at 70 eV and the determination was made by means of SIM mode, selected monitoring ion (m/z) was 264 amu. The detection limit was 0.02 mg/kg. The average recovery was from 86.7% to 93.1% and CV (n = 10) is from 4.1% to 5.9%. This method was already used to determine the mass concentration of pentachlorophenol residues in raw cotton, towel, shirt, leather gloves, leather watchguard. The method is simple, rapid and accurate.

Environmental Pollutants↗
PubMed2006

Cr(III) and Cr(VI) in leather and elicitation of eczema.

The aim of the present study was to investigate the relation between the content of Cr(VI) and soluble Cr(III) in leather and the ability of the leather to elicit eczema in chromium allergic patients. An array of chromium-tanned leather samples was analysed for the content of total Cr(VI) and soluble Cr(III) using the DIN 53314 and the DS/EN 420 methods. Subsequently, a group of 15 patients with a history of foot eczema and leather exposure was exposed to a selection of 14 chromium- and 1 vegetable-tanned leather sample on the upper back for 48 hr. In addition, one leather sample was used for a prolonged 14-day exposure study. In total, 4 of the 15 patients reacted to at least one leather sample, and 5 of the 14 leather samples elicited a reaction in at least 1 patient. The prolonged exposure study demonstrated that an extended exposure period may reveal allergenic potential of a leather sample not otherwise identified using an ordinary 48-hr exposure period. No relation was observed between the measured content of Cr(VI) and soluble Cr(III) in the leather and the elicitation of eczema. Thus, in order to evaluate the quality of chromium-tanned leather in relation to preventing allergic skin reactions, other more clinical relevant methods reflecting the actual bioavailable Cr(III) and Cr(VI) fractions should be developed.

Chromium Compounds↗
PubMed2026

Circular upcycling of waste toner into eco-safe superparamagnetic nano-Fe3O4@C core-shell pigment for sustainable magnetic leather coatings.

The widespread use of laser printing and photocopying technologies has led to the accumulation of waste toner powder (WTP), a chemically stable and potentially carcinogenic pollutant. Herein, a scalable pyrolysis approach is demonstrated for converting WTP into a functional magnetic pigment for magnetic leather finishing. Pyrolysis at 600 °C for 2 h, guided by thermogravimetric analysis, enabled controlled phase transformation monitored by hyphenated TGA-FTIR. The resulting material (WTP-600) was comprehensively characterised using VSM, FTIR, XPS, pXRD, FESEM, HRTEM, EDX, 57Fe Mössbauer analysis, ICP-OES and TOC analysis. These analyses confirm near-complete removal of the polymeric fraction during pyrolysis, leading to an ≈ 97% reduction in volume of pristine WTP and the formation of a carbonaceous shell coated on a superparamagnetic nanocrystalline Fe3O4 core (Fe3O4@C). The carbonaceous surface of WTP-600 is enriched with hydroxyl functionalities; it is eco-friendly, and its magnetic strength is ≈ 2.3-fold higher than that of pristine WTP. Both WTP and WTP-600 were formulated with a commercial leather-finishing dispersion and applied as surface finishing on leather. As anticipated, the magnetic strength of WTP-600-coated leather was approximately 2.3 times higher than that of WTP-RT-coated leather. Evaluation of coating performance parameters and organoleptic assessment demonstrated that WTP-600-coated leather exhibited superior surface finishing and tactile properties compared to WTP-RT-coated leather. Magnetic leather of various colours was successfully synthesised by incorporating different pigments into WTP-600, resulting in only a marginal reduction in magnetic properties. The magnetic pigment-coated leather was found to be microbiologically stable, environmentally safe, and cytocompatible with human epidermal HaCaT keratinocyte cell lines. The prepared magnetic leathers demonstrate significant potential for advanced applications, including adhesive-free wall tiling, educational tool fabrication, and energy harvesting from human motion.

Magnetic leather finishes↗
PubMed2000

Pretanned leather shavings in a supplement mixture for steers: I. In situ and in vitro disappearance, ruminal fermentation, and organic matter, nitrogen, and fiber digestion.

Two digestion studies were conducted to evaluate the use of pretanned leather shavings as a component of a protein supplement. In Exp. 1, the in situ and in vitro disappearance of pretanned leather shavings and soybean meal was evaluated. Results revealed that less than 18.4% of the pretanned leather shavings was solubilized and disappeared when exposed to McDougall's buffer for 48 h, but there was 90.0% disappearance with 48-h exposure to a .1 N HCl/pepsin treatment and 97.0% disappearance with exposure to a two-stage digestion. In situ disappearance following 72 h in the rumen allowed 6.8% disappearance. Thus, leather shavings seem to be relatively indigestible in the rumen, but postruminal digestion may be possible. In Exp. 2, six Angus x Holstein steers, fitted with ruminal and duodenal cannulas, were used in a replicated 3 x 3 Latin square to evaluate ruminal and digestion effects of the following supplements combined with fescue hay at 1.7% of BW (DM basis): no supplementation (control); supplementation intraruminally with soybean meal at .07% of BW (as-fed basis); and supplementation intraruminally with a combination of soybean meal and pretanned leather shavings (17:8 ratio) at .05% of BW (isonitrogenous to soybean meal; as-fed basis). Ruminal fluid passage rate was greater and fluid turnover time was shorter in steers fed leather shavings than in those fed soybean meal (P = .10). Ruminal pH was lower (P = .04) for supplemented steers than for control steers and ruminal NH3 N concentration was greater (P = .01) in steers fed soybean meal than in those fed leather shavings. Total VFA concentration was increased (P = .02) by supplementation. Supplementation with soybean meal increased (P < .05) ruminal molar proportions of butyrate, valerate, and isovalerate compared with leather shavings. Duodenal OM flow and OM disappearing in the intestines were increased by supplementation (P < .10), but not by the type of supplement fed (P > .10). Ruminal digestion of OM and total tract OM digestion were unaffected (P > .10) by supplementation and the type of supplement fed. Flow and digestion of NDF were unaffected (P > .10) by the treatments. Flow of N and the quantity of N disappearing in the intestines were increased (P < .05) by supplementation but did not differ (P > .10) between supplementation groups. Microbial N flow, N utilization for net microbial protein synthesis, and ruminal N disappearance were unaffected (P > .10) by supplementation and the type of supplement provided. Combining pretanned leather shavings with soybean meal seemed to have no deleterious effects on digestion or fermentation and to allow for escape of some N to the lower tract.

Animal Feed↗
PubMed2006

Biodegradability of leathers through anaerobic pathway.

Leather processing generates huge amounts of both solid and liquid wastes. The management of solid wastes, especially tanned leather waste, is a challenging problem faced by tanners. Hence, studies on biodegradability of leather become imperative. In this present work, biodegradability of untanned, chrome tanned and vegetable tanned leather under anaerobic conditions has been addressed. Two different sources of anaerobes have been used for this purpose. The effect of detanning as a pretreatment method before subjecting the leather to biodegradation has also been studied. It has been found that vegetable tanned leather leads to more gas production than chrome tanned leather. Mixed anaerobic isolates when employed as an inoculum are able to degrade the soluble organics of vegetable tanned material and thus exhibit an increased level of gas production during the initial days, compared to the results of the treatments that received the anaerobic sludge. With chrome tanned materials, there was not much change in the volume of the gas produced from the two different sources. It has been found that detanning tends to improve the biodegradability of both types of leathers.

Anaerobiosis↗
PubMed2003

Studies on the use of power ultrasound in leather dyeing.

Uses of power ultrasound for acceleration/performing the chemical as well as physical processes are gaining importance. In conventional leather processing, the diffusion of chemicals through the pores of the skin/hide is achieved by the mechanical agitation caused by the paddle or drumming action. In this work, the use of power ultrasound in the dyeing of leather has been studied with the aim to improve the exhaustion of dye for a given processing time, to reduce the dyeing time and to improve the quality of dyed leather. The effect of power ultrasound in the dyeing of full chrome cow crust leather in a stationary condition is compared with dyeing in the absence of ultrasound as a control experiment both in a stationary as well as conventional drumming condition. An ultrasonic cleaner (150 W and 33 kHz) was used for the experiments. Actual power dissipated into the system was calculated from the calorimetric measurement. Experiments were carried out with variation in type of dye, amount of dye offer, temperature and time. The results show that there is a significant improvement in the percentage exhaustion of dye due to the presence of ultrasound, when compared to dyeing in absence of ultrasound. Experiments on equilibrium dye uptake carried out with or without ultrasound suggest that ultrasound help to improve the kinetics of leather dyeing. The results indicate that leathers dyed in presence of ultrasound have higher colour values, better dye penetration and fastness properties compared to control leathers. The physical testing results show that strength properties of the dyed leathers are not affected due to the application of ultrasound under the given process conditions. Apparent diffusion coefficient during the initial stage of dyeing process, both in presence and in absence of ultrasound was calculated. The values show that ultrasound helps in improving the apparent diffusion coefficient more for the difficult dyeing conditions such as in the case of metal-complex dyes having bigger aggregate size compared to less difficult dyeing conditions.

Journal Article↗
PubMed2004

Power ultrasound-assisted cleaner leather dyeing technique: influence of process parameters.

The application of power ultrasound to leather processing has a significant role in the concept of "clean technology" for leather production. The effect of power ultrasound in leather dyeing has been compared with dyeing in the absence of ultrasound and conventional drumming. The power ultrasound source used in these experiments was ultrasonic cleaner (150 W and 33 kHz). The effect of various process parameters such as amount of dye offer, temperature, and type of dye has been experimentally found out. The effect of presonication of dye solution as well as leather has been studied. Experiments at ultrasonic bath temperature were carried out to find out the combined thermal as well as stirring effects of ultrasound. Dyeing in the presence of ultrasound affords about 37.5 (1.8 times) difference as increase in % dye exhaustion or about 50% decrease in the time required for dyeing compared to dyeing in the absence of ultrasound for 4% acid red dye. About 29 (1.55 times) increase in % dye exhaustion or 30% reduction in time required for dyeing was observed using ultrasound at stationary condition compared with conventional dynamic drumming conditions. The effect of ultrasound at constant temperature conditions with a control experiment has also been studied. The dye exhaustion increases as the temperature increases (30-60 degrees C) and better results are observed at higher temperature due to the use of ultrasound. Presonication of dye solution or crust leather prior to the dyeing process has no significant improvement in dye exhaustion, suggesting ultrasound effect is realized when it is applied during the dyeing process. The results indicate that 1697 and 1416 ppm of dye can be reduced in the spent liquor due to the use of ultrasound for acid red (for 100 min) and acid black (for 3 h) dyes, respectively, thereby reducing the pollution load in the effluent stream. The color yield of the leather as inferred from the reflectance measurement indicates that dye offer can be halved when ultrasound is employed to promote dyeing. Scanning electron microscopy analysis of the cross section of the dyed leather indicates that fiber structure is not affected due to the use of ultrasound under the given process conditions. The present study clearly demonstrates that ultrasound can be used as a tool to improve the rate of exhaustion of dye, reduce pollution load in the spent effluent liquor, and improve the quality of leather produced. The study also offered provision to employ optimum levels of chemicals and increases percentage exhaustion for a given time, thereby limiting the pollution load in the tannery effluent, which is of great social concern.

Animals↗
PubMed2002

Contact allergens in shoe leather among patients with foot eczema.

Some patients with relapsing foot eczema and a shoe leather allergy, who fail to show positive results with standard series and shoe wear screening tray patch testing, do not respond to the use of hypoallergenic shoe leather. We assume that relevant allergens are present in hypoallergenic shoe leather. We described an experiment to demonstrate the presence of these allergens. Alcoholic extracts were made of green, black and undyed hypoallergenic shoe leather, and the extracts were fractioned by paper chromatography. The resulting chromatograms were cut into 16 equal paper disks and patch tests were performed with extracts and the paper chromatography fractions. Positive reactions were seen to all extracts and to fractions of all types of leather. From analysis of the pattern of positive patch tests we concluded that leather-related allergens (e.g. tanning agent) and dyes were present in hypoallergenic shoe leather. In these cases, alternatives to shoe leather should be sought, for instance wooden or plastic shoes.

Dermatitis, Allergic Contact↗
PubMed1986

Bladder cancer and occupational exposure to leather.

A large case-control study of bladder cancer (2982 cases; 5782 controls) included information about occupational exposure to leather. Occupational histories of exposed white study subjects were reviewed and 150 were determined to have had "true" on the job exposure to leather. The odds ratio estimate (OR) of bladder cancer associated with such exposure in white subjects (n = 8063) was 1.4 (95% confidence limits = 1.0, 1.9) after adjustment for sex, age, and cigarette smoking. The risk was highest in those first employed in a leather job before 1945, although no dose-response relation with duration of leather employment was found. Subjects employed in "dusty" leather jobs had a slightly higher risk than those with other types of leather jobs. Our results are consistent with reports of an increased risk of bladder cancer associated with exposure to leather. Although the agents responsible have not been identified, our findings of an increased risk associated with exposure in the earlier years of this century and in dusty jobs suggest that leather dusts may be important.

Adult↗
PubMed2000

Pretanned leather shavings in a supplement mixture for steers: II. Digesta kinetics, ruminal fermentation, and grazing behavior in steers grazing dormant wheatgrass pasture.

Twelve ruminally cannulated steers (Angus x Holstein; average initial BW = 533 +/- 3.28 kg) were randomly allotted to one of three treatments (four steers/treatment) to evaluate the use of pretanned leather shavings as a component of a protein supplement for steers grazing dormant intermediate wheatgrass (Thinopyrum intermedium Host). Steers were allotted to one of three treatments: 1) no supplement (control); 2) supplementation intraruminally at 0700 with soybean meal at .2% of BW (as-fed basis); 3) supplementation intraruminally with soybean meal and pretanned leather shavings (17:8 ratio, respectively) at .16% of BW (as-fed basis). Supplements were formulated so that intakes were isonitrogenous and were placed intraruminally once daily (0700). Sampling periods were conducted February 3 to 16 and February 17 to March 5, 1995. In situ organic matter disappearance of the soybean meal supplement was greater (P > .05) than that of the leather shavings supplement at all incubation times (1, 3, 6, 9, 12, 24, and 48 h). Data suggested that pretanned leather shavings within the leather shavings supplement were only 25% degradable within the rumen. Forage OM intake (control = 12.7, soybean meal = 12.7, and leather shavings = 13.4 g/kg of BW), grazing time, and grazing efficiency were not altered (P > .10) by supplementation or type of supplement provided but did increase between the February and March samplings. Total intake was increased (P = .09) with supplementation and reflected the addition of the protein supplements. Particulate and fluid passage estimates were unaffected (P > .10) by the supplements; however, gastrointestinal fill increased (P = .01) between the February and March samplings. Ruminal pH was lower (P = .04) and ruminal NH3 N concentration was greater (P = .02) for supplemented steers than for control steers, and supplementation treatments did not differ (P > .10). Total VFA concentrations were increased (P = .01) by supplementation but were not affected by type of supplement provided (P > .10). Ruminal molar proportions of acetate and propionate and the ratio of these two VFA did not differ (P > .10) between supplementation types. Nonetheless, supplementation increased molar proportions of butyrate (P = .04), valerate (P = .02), and isovalerate (P = .05), and leather shavings supplementation increased (P = .10) isobutyrate proportions over those in steers supplemented with soybean meal. Combining pretanned leather shavings with soybean meal seemed to have no deleterious effects on forage intake, digesta passage, grazing behavior, or ruminal fermentation and seemed to provide effects similar to those of soybean meal alone.

Animal Feed↗
PubMed2004

Thermal valorization of footwear leather wastes in bubbling fluidized bed combustion.

Transformation of hide (animal skins) into leather is a complicated process during which significant amounts of wastes are generated. Footwear is the sector that consumes the major part of leather (60%). Logically, this industry is producing the largest quantity of leather wastes. The objective of this work was to demonstrate the technical feasibility of fluidized bed technology to recover the energy from burning footwear leather wastes. Considering the characteristics of leather waste, especially the heating value (12.5-21 MJ/kg), it can be considered a fairly good fuel. Moreover, leather waste has suitable characteristics for combustion, e.g., high volatile matter (76.5%) and low ash content (5.2%). Two factors deserve special attention: N3O and NOx emissions as a consequence of its unusual high nitrogen content (14.1%) and the chromium speciation because chromium is the main element of ash (3.2%) due to its use in leather tanning. A series of experiments has been carried out in a 0.1 MWt bubbling fluidized bed pilot plant. The combustion efficiency, flue gas composition and chromium speciation were investigated. Despite having high nitrogen content, a low conversion rate of fuel-N to NOx and N2O was attained. Chromium was concentrated in the solid streams and it was consistently found as Cr(III+); no presence of Cr(VI+) was detected.

Ammonia↗
PubMed2005

Studies on the influence of power ultrasound on dye penetration in leather dyeing using photomicrographic analysis.

The use of power ultrasound in enhancing diffusion rate in various chemical as well as physical processes is gaining in importance. The influence of power ultrasound in the leather dyeing process on enhancing the penetration of dye through the leather matrix was studied. The penetration of dye through a leather cross-section for a given time in the presence and absence of an ultrasonic field (33 kHz, 150 W) was studied by photomicrographic analysis using a stereomicroscope. Different types of black dyes, such as Acid black 1, Metal complex black 194 and Direct black 155, were used for dyeing leather in the present study. Photomicrographic analysis of a cross-section of dyed leather indicated better penetration of dyes through the leather matrix with the use of ultrasound than without it. Therefore, the results indicate that ultrasound helps to improve the diffusion of dye and to reduce diffusional resistance in the leather dyeing process.

Journal Article↗
PubMed1996

Cancer incidence and specific occupational exposures in the Swedish leather tanning industry: a cohort based case-control study.

OBJECTIVE: To study the effect on the incidence of cancer of exposure to chemicals handled in the leather tanning industry. MATERIALS AND METHODS: A case-control study was performed within a cohort of 2487 workers employed for at least six months during the period 1900-89 in three Swedish leather tanneries. 68 cancer cases (lung, stomach, bladder, kidney, nasal, and pancreatic cancers and soft tissue sarcomas) and 178 matched controls were studied. Effects of chemical exposures on cancer incidence, adjusted for age at risk, sex, and plant were estimated with a conditional logistic regression model. RESULTS: A significant association was found between exposure to leather dust and pancreatic cancer (odds ratio (OR) 7.19, 95% confidence interval (95% CI) 1.44 to 35-89). An association was indicated between leather dust from vegetable tanning and lung cancer. After adjustment for smoking habits a tentative association between organic solvents and lung cancer lost its significance. No association was found between exposure to chlorophenols and soft tissue sarcomas. CONCLUSIONS: The significant association between leather tanning and soft tissue sarcomas that was found in our previous cohort analysis could not be explained by exposure to chlorophenols. On the other hand a significant association was found between exposure to leather dust and pancreatic cancer, and exposure to leather dust from vegetable tanning was often present in cases with lung cancer. Due to the small numbers of cases, the results can, however, only lead to tentative conclusions.

Adult↗