Tanning Agent Research Articles

Removal of chromium from tanning wastewater and its reuse

The chromium (Cr) used in the manufacture of leather from hides has well-known adverse effects when inappropriately disposed in the environment. The tanneries use large quantities of water for processing hides. The recovery of Cr from the wastewater produced in the tanning step is an environmentally friendly and economically viable alternative avoiding the disposal of large amount of Cr-containing sludge in industrial hazardous waste landfills. This work aims at studying the removal of the Cr from the tanning wastewater through chemical precipitation (CP) and electrocoagulation (EC) techniques and its reuse in tanning process. In the CP experiments, efficient Cr removal from wastewater samples was achieved, with up to 99.74% removal efficiencies. In the EC experiments, three different electrode materials, Al, Cu, and Fe were tested. The highest removal efficiency of 97.76% was obtained with Al electrodes by conducting electrolysis at 3.0V for 110min. This was followed by Fe electrodes and Cu electrodes, which showed removal efficiencies of 90.27% (at 2.5V) and 69.91% (at 2.0V), respectively, for an electrolysis of 100min. The recovered Cr was reused as a tanning agent in leather processing, where good crossing of Cr was reached in leathers tanned with the liquors prepared from the sludge, and the pH and ash content values were measured. While the hides tanned with the Cr-containing liquor recovered by CP and by EC with Cu electrodes showed good hydrothermal stability and Cr content above 2.5% Cr2O3, the hides tanned with Cr-containing liquors recovered by chemical precipitation and by EC conducted with Fe and Cu electrodes showed contents of Cr according to technical specifications. However, the Cr samples obtained with the iron electrode showed a dark coloration due to oxidation of the iron. It can be concluded that the tanning process with Cr recovered by CP and by EC with Cu electrodes showed the best results.

Phenolic Compounds from Roots of Lupinus polyphyllus

We reported earlier on the isolation from Lupinus polyphyllus Lindl. roots of 20 organic acids, among which 10 were carboxylic; 2, phenolic; and 8, fatty acids [1]. The goal of the present work was to study phenolic compounds from L. polyphyllus roots. We studied roots collected during fruiting in September 2014 in Kharkov Region of Kharkov Oblast. Total phenolic compounds were separated into individual components using HPLC on an Agilent Technologies 1200 3 D LC System chromatograph (USA) equipped with G1325C diode-matrix and G1362A refractometric detectors. The investigation used reversed-phase (RP) chromatography over a Supelco Discovery C18 chromatography column (250 4.6 mm) with silica gel (5 m) modified by octadecyl groups. The mobile phase was solvent A [0.1% trifluoroacetic acid (TFA), 5% MeCN, H2O, pH 2.08] and solvent B (0.1% TFA, MeCN). The chromatography conditions were mobilephase flow rate 0.1 mL/min, eluent operating pressure 400 bar (40 kPa), column thermostat temperature 25°C, sample volume 10 L, and chromatography time 40 min. We used gradient elution. The scan time was 0.6 s at wavelengths 280 and 255 nm. Ground raw material (2.0 g, accurate weight) was placed into a 100-mL flask and extracted with refluxing doubly distilled H2O (50 mL) for 30 min on a boiling-water bath. The obtained extract was filtered, cooled, transferred to a 100-mL flask, and adjusted to the mark with doubly distilled H2O [2]. The quantitative contents in L. polyphyllus roots of gallic and ellagic acids, (+)-catechin, (+)-catechin gallate, (–)-epicatechin, epicatechin gallate, and epigallocatechin were analyzed by RP chromatography. Table 1 presents the results. The phenolic composition of L. polyphyllus roots was studied. The quantitative contents of isolated compounds, the total of which was 1.972%, were determined. The dominant compounds with respect to quantity ( g/ L) were (–)-epicatechin, 213.05376; (+)-catechin, 208.05657; and (–)-epigallocatechin, 154.95159. This indicated that L. polyphyllus roots contained mainly condensed tanning agents.

Effects of Chromium-olation Length on Crosslinking Effects Investigated by Molecular Dynamics Simulation

In this article, the attempt has been made to study the effect of chromium-olation length on the properties of the chrome-cross-linked collagen by molecular dynamics simulation with modified CHARMM force field. The results indicated that the advantage of the chromium tanning agents depend not only on their unique olation structures, but also on their various olation lengths coexisting in the tanning environment. Short chromium-olation complexes predominantly strengthen the conformation stability within the triple helix. Medium chromium-olation complexes may stabilize the cross-linked systems by an effective optimization of the nonbonding interaction. Long chromium-olation length favors the cross-linking between the collagen bundles far from each other, but is easy to cause the divorce of the individual peptide chain from its parent triple helix. Accordingly, the application of mixed cross-linking agents suggests variations in size within a reasonable range should provide greater effects than single-length ones.

Development and evaluation of polyherbal Entoban syrup

Aim: The present study was focused on development and evaluation of polyherbal syrup Entoban to confirm its quality and potency. Methods: The developed syrup was evaluated for different physicochemical factors including physical appearance, pH and specific gravity. Stability was determined by keeping the samples at accelerated temperature conditions. Results: The formulation exhibited brown color, sweet taste and characteristic odor. The developed polyherbal syrup found to have pH 3.7 and specific gravity 1.324. Both the alkaloids and tanning agents were within the specified limits. The syrup was in compliance of the permissible microbial limits. The stability study revealed that no changes were noticed in all the tested physicochemical parameter as well as turbidity/homogeneity during 24 hrs, 48 hrs and 72 hrs. Conclusions: The evaluation undertaken reveal compliance with all the physicochemical and analytical procedures, therefore it is concluded that Entoban syrup is well standardized product at the base line parameters.

Visible light photocatalytic degradation of wattle extract: effect of mixing CdWO4 over a semiconductive ZnO photocatalyst

Degradation of wattle (Acacia mearnsii) extract, a leather tanning agent which is mainly composed of polyphenolic compounds was attempted by photocatalytic degradation.

Chemical functionalization and stabilization of type I collagen with organic tanning agents

We investigated the interactions between selected organic tanning agents and type I fibrillar collagen as a model fibrillar substrate to enable the fast direct evaluation and validation of interpretations of tanning activity. Type I fibrillar collagen (1%) as gel was used as substrate of tanning and tannic acid, resorcinol- and melamine-formaldehyde and their combination at three concentrations as crosslinking agents (tannins). To evaluate the stability of collagen during tanning, the crosslinked gels at 2.8, 4.5 and 9.0 pHs were freeze-dried as discs which were characterized by FT-IR, shrinkage temperature, enzymatic degradation and optical microscopy, and the results were validated by statistical analyses. The best stability was given by combinations between resorcinol- and melamine-formaldehyde at isoelectric pH.

Pollution reduction in an eco-friendly chrome-free tanning and evaluation of the biodegradation by composting of the tanned leather wastes

Abstract Chromium is one of the most important environmental concerns related to tanneries. The most often used process for hide tanning is chrome tanning. This implies the presence of chromium both in wastewaters and in leather wastes. Leather wastes have to be disposed in landfills what entails a considerable environmental impact and high cost. In this work, a study about the effect of a chrome-free tanning process using titanium salts instead, on the wastewater and on the solid wastes has been performed. In this way, a study of biodegradation of leather waste samples tanned with different tanned agents by composting together with food wastes is carried out in a laboratory composter. Results indicated that leather tanned with titanium salts met the required quality standards. Besides, the concentration of organic matter and salts in the tannery process wastewater was lower comparing with the chromium tanning agent. In the biodegradation study by composting, leather samples tanned with titanium were degraded, reducing around 10% the carbon content with the subsequent diminution of the C/N ratio. In addition, the size was reduced 41% in 45 days. However, leather sample tanned with oxazolidine was partially degraded in the composter; meanwhile chrome and vegetable tanned leather kept inalterable.

Removal of organic pollutants in tannery wastewater from wet-blue fur processing by integrated Anoxic/Oxic (A/O) and Fenton: Process optimization

Abstract Treatment of tannery wastewater has been a challenge in remediation of aquatic environment in developing countries. Removal of organic pollutants in tannery wastewater from wet-blue fur processing was studied using integrated processes of Anoxic/Oxic and Fenton. Analysis of COD composition based on particle size found about 10% of the total COD was in the particulate and colloidal range, the remaining 90% was soluble with 72% biodegradable. Biodegradation of real tannery wastewater as well as typical tanning agents were performed in batch experiments, aerobic degradation presented much better performance than anaerobic degradation. Effect of hydraulic retention time on A/O performance in terms of COD removal efficiency was evaluated, excess HRT like 60 h would reduce the effluent quality, and the appropriate organic load rate was at least up to 0.8 kg COD m −3 d −1 with corresponding COD removal of about 80%. In the subsequent Fenton oxidation, effects of initial pH and H 2 O 2 dose on COD removal were investigated, and response surface methodology was adopted to obtain the optimal conditions as initial pH of 4.0, H 2 O 2 dose of 14.0 mM, H 2 O 2 :Fe 2+ molar ratio of 10.6, and reaction time of 3 h to achieve the highest COD removal of 55.87%. GC–MS analysis was carried out to observe the change of organic composition during Fenton oxidation, and most of the residual organic pollutants resistant to Fenton treatment belonged to organosilanes and saturated alkanes. This study will provide useful information for treatment of a special type of tannery wastewater from wet-blue fur processing with low organic load.

Oxalic acid production by citric acid-producing Aspergillus niger overexpressing the oxaloacetate hydrolase gene oahA

The filamentous fungus Aspergillus niger is used worldwide in the industrial production of citric acid. However, under specific cultivation conditions, citric acid-producing strains of A. niger accumulate oxalic acid as a by-product. Oxalic acid is used as a chelator, detergent, or tanning agent. Here, we sought to develop oxalic acid hyperproducers using A. niger as a host. To generate oxalic acid hyperproducers by metabolic engineering, transformants overexpressing the oahA gene, encoding oxaloacetate hydrolase (OAH; EC 3.7.1.1), were constructed in citric acid-producing A. niger WU-2223L as a host. The oxalic acid production capacity of this strain was examined by cultivation of EOAH-1 under conditions appropriate for oxalic acid production with 30 g/l glucose as a carbon source. Under all the cultivation conditions tested, the amount of oxalic acid produced by EOAH-1, a representative oahA-overexpressing transformant, exceeded that produced by A. niger WU-2223L. A. niger WU-2223L and EOAH-1 produced 15.6 and 28.9 g/l oxalic acid, respectively, during the 12-day cultivation period. The yield of oxalic acid for EOAH-1 was 64.2 % of the maximum theoretical yield. Our method for oxalic acid production gave the highest yield of any study reported to date. Therefore, we succeeded in generating oxalic acid hyperproducers by overexpressing a single gene, i.e., oahA, in citric acid-producing A. niger as a host.

Influence of ultrasound on Avaram bark (Cassia auriculata) tannin extraction and tanning

Efficient processing methodologies such as ultrasounds which would achieve significant enhancements in processes thereby minimizing sectional stream wastes in one hand and bring about economic benefits on other are necessary. Hence, research studies on application of ultrasound in process industries such as leather, textiles and chemicals are gaining importance. In this regard, a case study has been presented in this paper for solid–liquid tanning extraction and tanning from a plant material. For this purpose, Avaram bark (Cassia auriculata) which contains ingredients such as polyphenolics, useful in stabilization of collagen, which is the main constituent of skins/hides. Avaram bark tannin come under the group of ‘condensed tannins’ useful in main tanning process of leather making. The influence of various process parameters such as ultrasonic power, time and agitation on extraction has been studied. The results show significant 1.6-fold improvement for total extract due to the use of ultrasound, 100W as compared to magnetic stirring control process, suggesting better mass transfer enhancement in leaching of strongly bound tannins from avaram bark due to ultrasound. Efficacy of tannin extract (10% or 20% offer) has been analyzed through application in tanning process and found to be useful. There has been significant improvement in rate of tannin uptake for ultrasonic extract as compared to control extract by the bovine pelt, suggesting diffusion enhancement of tanning agent through the pelt matrix. Use of ultrasound in avaram extract tanning has also been studied and found to be useful. Therefore, the present study clearly indicates the use of ultrasound in Avaram bark tannin extraction and tanning as a viable option with added advantages even dispensing with external heating.

Dihydroxyacetone disturbs collagen fibril formation due to side chain modifications by glycation (979.1)

Glycation is a spontaneous process typically initiated with a condensation reaction between a reducing sugar and a protein, leading to the formation of Advanced Glycation Endproducts (AGEs). The in vivo accumulation of AGEs has been shown to modify the side chains of long lived proteins such as collagen, resulting in the alteration of their functions. The objective of this study was to use a combination of analytical techniques to evaluate the effect of dihydroxyacetone (DHA), an FDA approved tanning agent, on collagen glycation and fibril formation. Fluorescence spectroscopy revealed that DHA readily glycated collagen and induced the formation of AGEs. Moreover, addition of DHA to a collagen solution disturbed fibril formation, an observation confirmed by both UV spectroscopy and transmission electron microscopy (TEM). Compared to control solutions with collagen alone, addition of DHA showed a similar extent of fibril formation, but with a much lower rate, suggesting a reversible association of DHA which was displaced during collagen self‐assembly. The extent of fibril formation of collagen pre‐incubated with DHA for 24 hours, however, was significantly lower than untreated collagen, suggesting that DHA irreversibly glycated the collagen side chains and such modification prevented the self‐assembly of collagen necessary for fibril formation. Our future studies will focus on characterizing the DHA modification of the collagen side chains and assessing the correlation between collagen fibril formation kinetics and the degree of DHA induced glycation.

Characterization of Thermotoga maritima glycerol dehydrogenase for the enzymatic production of dihydroxyacetone

NAD-dependent Thermotoga maritima glycerol dehydrogenase (TmGlyDH) converts glycerol into dihydroxyacetone (DHA), a valuable synthetic precursor and sunless tanning agent. In this work, recombinant TmGlyDH was characterized to determine if it can be used to catalyze DHA production. The pH optima for glycerol oxidation and DHA reduction at 50°C were 7.9 and 6.0, respectively. Under the conditions tested, TmGlyDH had a linear Arrhenius plot up to 80°C. TmGlyDH was more thermostable than other glycerol dehydrogenases, remaining over 50% active after 7h at 50°C. TmGlyDH was active on racemic 1,2-propanediol and produced (R)-1,2-propanediol from hydroxyacetone with an enantiomeric excess above 99%, suggesting that TmGlyDH can also be used for chiral synthesis. (R)-1,2-propanediol production from hydroxyacetone was demonstrated for the first time in a one-enzyme cycling reaction using glycerol as the second substrate. Negative cooperativity was observed with glycerol and DHA, but not with the cofactor. Apparent kinetic parameters for glycerol, DHA, and NAD(H) were determined over a broad pH range. TmGlyDH showed little activity with N(6)-carboxymethyl-NAD(+) (N(6)-CM-NAD), an NAD(+) analog modified for easy immobilization to amino groups, but the double mutation V44A/K157G increased catalytic efficiency with N(6)-CM-NAD(+) ten-fold. Finally, we showed for the first time that a GlyDH is active with immobilized N(6)-CM-NAD(+), suggesting that N(6)-CM-NAD(+) can be immobilized on an electrode to allow TmGlyDH activity in a system that reoxidizes the cofactor electrocatalytically.

Removal of leather tanning agent syntan from aqueous solution using Fenton oxidation followed by GAC adsorption

The optimum conditions for the removal of leather tanning agent syntan from aqueous solution by Fenton oxidation at 22°C for an initial syntan concentration of 500mg/L were pH 3, and concentrations of H2O2 and FeSO4 of 300mg/L and 500mg/L, respectively. Fenton oxidation followed by granular activated carbon (GAC) adsorption in fixed-bed column resulted in more than 95% removal of dissolved organic carbon, compared to 55–70% removal by Fenton oxidation alone and GAC adsorption alone. The removal of individual organic fractions was also higher for the combined treatment compared to the Fenton oxidation alone.

SMART: An Internet study of users experiences of synthetic tanning

AimsSocio-cultural values placed on skin tanning equating with health and attractiveness, along with recommended avoidance of excessive UV exposure has fuelled the manufacture, sale and dissemination of synthetic tanning agents. These agents are synthetic analogues of the naturally occurring melanocyte-stimulating hormones (α-MSHs) which stimulate darkening pigmentation of the skin. Despite health marketability and online consumerism, user focused research to date is limited. MethodsThe study presents a unique phenomenological study of user experiences as described on a popular melanotan web resource. Seven themes containing 91 categories were generated from the 467 discussion threads analysed using the Empirical Phenomenological Psychological (EPP) five step method. ResultsMelanotan use is covert by nature and grounded in intentions to achieve a natural looking tan. Positive outcomes outweigh potential risk perceptions in users, despite awareness of lack of regulation of synthetic tanning products and absence of user instructions. Products are marketed online as ‘lifestyle choices’, sold as ‘research chemicals’ and labelled ‘not for human use’ to avoid regulation. A host of acute and chronic side effects, and options for pharmaceutical management of histamine and dermatological responses were described. ConclusionsFindings illustrate the importance of cyber forums in advocating tentative and calculative approaches to injecting preparation, dosage, photo therapy, loading and maintenance regimes using Melanotan I and II. ImplicationsDetermination of how to respond effectively to market forces and cyber communities of users necessitates continued researcher, clinician, policy maker and practitioner dialogue, along with ongoing surveillance of trends of sale, supply and use.

Valorization of titanium metal wastes as tanning agent used in leather industry

The development of new tanning agents and new technologies in the leather sector is required to cope with the increasingly higher environmental pressure on the current tanning materials and processes such as tanning with chromium salts. In this paper, the use of titanium wastes (cuttings) resulting from the process of obtaining highly pure titanium (ingots), for the synthesis of new tanning agent and tanning bovine hides with new tanning agent, as alternative to tanning with chromium salts are investigated. For this purpose, Ti waste and Ti-based tanning agent were characterized for metal content by inductively coupled plasma mass spectrometry (ICP-MS) and chemical analysis; the tanned leather (wet white leather) was characterized by Scanning Electron Microscope/Energy Dispersive Using X-ray (Analysis). SEM/EDX analysis for metal content; Differential scanning calorimetric (DSC), Micro-Hot-Table and standard shrinkage temperature showing a hydrothermal stability (ranged from 75.3 to 77°C) and chemical analysis showing the leather is tanned and can be processed through the subsequent mechanical operations (splitting, shaving). On the other hand, an analysis of major minor trace substances from Ti-end waste (especially vanadium content) in new tanning agent and wet white leather (not detected) and residue stream was performed and showed that leachability of vanadium is acceptable. The results obtained show that new tanning agent obtained from Ti end waste can be used for tanning bovine hides, as eco-friendly alternative for chrome tanning.

Eco-friendly titanium tanning for the manufacture of bovine upper leathers: pilot-scale studies

Conventional chrome-tanning process is constantly under pressure from increasingly stringent environmental regulations on discharges of chromium-containing effluents and wastes. For this reason, in the past years alternative chrome-free tanning processes have been developed. Among these, titanium tanning is one of the most promising substitutes for chromium tanning in today’s leather industry. In this study the use of titanyl sulfate masked with citrate was investigated as tanning agent for the production of high-quality bovine upper leather on pilot scale. Preliminary experimental activities were performed to individuate the minimum citrate/titanium mole ratio to ensure a good titanium sulfate solution stability and minimum quantity of salt (sodium chloride) in pickling solution sufficient to depress acidic swelling of the skins. Ti-tanned leathers produced by the developed Ti-tanning process showed comparable physical–mechanical properties to those of traditionally Cr-tanned leathers, used as control, but a lower hydrothermal stability although acceptable. The Ti-tanned leathers complied with the standards for high-quality upper leather exhibiting better dyeability, due to their higher affinity to anionic dyestuffs, and similar softness, fullness, roundness, and hand compared to the control leathers.

Chromium electroplating from trivalent chromium baths as an environmentally friendly alternative to hazardous hexavalent chromium baths: comparative study on advantages and disadvantages

In this communication, we present a generalization of our investigations concerning current state in the development of trivalent chromium baths as an environmentally friendly alternative to hazardous electroplating baths containing extremely toxic hexavalent chromium compounds. The main technological properties of sulfate trivalent chromium baths containing carbamide and formic acid as organic additives are described and compared to those typical of common Cr(VI) plating bath. It is shown that thick nanocrystalline chromium–carbon deposits may be obtained from the Cr(III) electrolytes under study, with some physicochemical and service properties of such coatings exceeding those of “usual” chromium deposits. The proposed trivalent chromium baths are distinguished by their high current efficiency and electrodeposition rate. The covering power of the Cr(III) baths is poorer than in case of hexavalent chromium baths; it may be improved by applying basic chromium sulfate (chrome tanning agent) instead of chromium sulfate as a source of Cr(III) ions in solution. There is no need to utilize toxic lead anodes in Cr(III) deposition processes. It is noted that a grave shortcoming of trivalent baths is their low conductivity in comparison with the hexavalent ones.

Design, Development and Phytochemical Evaluation of a Poly Herbal Formulation Linkus Syrup

The present work has been carried out on polyherbal formulation named as Linkus Syrup. The herbal formulation consists of Glycyrrhiza glabra, Hyssopus officinalis, Piper longum and Alpinia galangal. The Linkus syrup physico-chemical evaluation such as pH, density, identification of polysaccharide, tanning agents, ascorbic acid and shelf life was complied. The TLC and quantitative determination of alkaloid were quantified. Determination of biomarker has been validated for the analysis of vasicine. The study result revealed that Linkus syrup formulation was well standardized at different levels such as physic-chemical consistency and assay of bio marker compound.

ИЗУЧЕНИЕ ХИМИКО-ТЕХНОЛОГИЧЕСКИХ СВОЙСТВ ЭТАНОЛЬНОГО ЭКСТРАКТА СОСНЫ, ПОЛУЧЕННОГО ИЗ ОКОРКИ ДРЕВЕСИНЫ, И ЕГО ВОЗМОЖНОГО ПРИМЕНЕНИЯ В КОЖЕВЕННО-МЕХОВОЙ ПРОМЫШЛЕННОСТИ

This paper investigated the effect of ethanol on the quality of the extract of pine produced from low-grade raw materials and their processing properties. We studied the relationship between views of the extractant and the degree of modification of collagen - the main skins' protein by simulating the process of tanning. The products of dissolution of collagen (PDC) treated with ethyl extract of pine were used as the model. The degree of modification was determined by differential scanning calorimetry. The investigations revealed that the alcohol extract of pine features a large tar content and a high degree of purity (~92,6%). Interaction between extractives and collagen goes mainly on amide nitrogen and the side carboxyl groups, with ε-amino groups and phenolic hydroxyl groups - that have probably been blocked by hydrogen bondsare – are being released. Heat resistance of coats derived from the tanned PDC is high enough, it can be concluded that there may be the possible use of alcohol extracts of pine in the leather and fur industry as a tanning agent.

Eco-Leather: Properties of Chromium-Free Leathers Produced with Titanium Tanning Materials Obtained from the Wastes of the Metal Industry

In this research, a new titanium tanning agent (TMW/2) obtained from the wastes of the metal industry was investigated in the production of chromium free eco-leather, by experimenting with various amounts of tanning agent and comparing the physical and chemical properties of the tanned leathers. The tanning process was performed with different concentrations of active titanium tanning material such as 1%, 2.5%, 5%, 7.5%, and 10%. The titanium content, chromium oxide content, formaldehyde content, shrinkage temperature, pH value, ash content, and fat content of the tanned leathers were investigated for the determination of chemical characterization. The tensile strength, elongation at break, tear strength, and colour measurement tests were also carried out for investigating the physical properties. The titanium tanned leathers had a mean shrinkage temperature of 79.5oC and more yellowish colour than the chromium tanned leathers. Their tensile strength properties were found similar with chromium leathers, while the elongation at break was found to be lower and tearing resistance was higher. The usage amount of 2.5% could be perfectly advised for the tanning process based on the titanium tanning material for achieving optimal properties required from different leather types such as upholstery, automotive and shoe upper leathers. Consequently, our results showed that this new titanium tanning agent could be used as an alternative tanning material in the production of chromium free eco-leathers considering the visual, physical, and chemical properties of resultant leathers.