To avoid environmental pressure from water authorities, specifically regarding nitrogen and sulfate limits in tannery wastewater, modifications to existing deliming processes have been made. Conventional ammonium salt deliming methods contribute to Total Kjeldahl Nitrogen values in the region of 0.5 – 1.0g/L (33-67% of total TKN). Sulfate levels are increased with the use of organic deliming and ammonium sulfate deliming to the extent of 0.9g/L (27% of total sulfate). To understand the dynamics and kinetics of carbon dioxide equilibrium, the movement of carbon dioxide into deliming water, through carbonic acid, bicarbonate and ultimately into carbonates at liming or early deliming pH was studied. It was shown in this study that effective lime removal, at optimum conditions, resulted in fully delimed pelts at highly comparable quality and times compared to conventional ammonium salt deliming

The activity of the tryptic enzymes occurring in the pyloric caeca of several salmons has been measured with respect to the effects of pH, ammonium chloride concentration and temperature on the enzyme bate material prepared from it. Several defferent methods of preparing a commercial bate have been investigated. From these data, an economic estimate of the feasibility of the production of leather bates from salmon pyloric caeca has been made. A sample of bate has been submitted for commercial testing. / Science, Faculty of / Zoology, Department of / Graduate

The objective of this investigation was to determine the effect of aeration in combination with chemical coagulation on the treatment of spent vegetable tan liquor. Chemical coagulation was desirable because it effectively reduced the color and suspended solids of the tanning waste. Aeration was thought to be a possible means of reducing the Chemical Oxygen Demand of the waste by biological stripping of the pyrogallol compound in the spent waste. Samples collected from the aeration-coagulation system were periodically analyzed for Chemical Oxygen Demand, pH, suspended solids, color removal, volume of sludge produced, and coagulant demand. These values were correlated with those values obtained for the characteristics of the raw spent waste. Color reductions up to 94 per cent were obtained up to an aeration period of 12 hours with a suspended solids reduction of 96 per cent.. Chemical Oxygen Demand reductions of the waste were increased throughout the period of aeration with a maximum reduction of 40 per cent at 36 hours of aeration. Significance of the five day Biochemical Oxygen Demand value of 25,600 mg/liter for the raw spent waste indicated a 4 to 5 increase over all reported values from the literature. / Master of Science

No description available.

One of the major problems facing the meat and leather industries is dung cladding on hides. Dung dried onto hides is difficult to remove during the early stages of processing, resulting in the necessity for prolonging the soaking step, with the consequence of risking bacterial damage to the hides. Microscopic examination of dung on hide reveals that adhesion is between the dung and the hair alone, with no sticking of the dung to the epidermis. This accounts for the difficulty in removing dry dung; the matrix of the hair within the dung creates a strong composite material. Analysis shows that major components of the composition of dung are lignocellulosic materials (lignin, hemicellulose and cellulose). This project concerns solubilising the dung faster, to reduce soaking time by targeting these components with enzyme technology, using hemicellulases, cellulases, and laccases from commercial products and a range of fungal organisms (Coriolus versicolor and Aspergillus niger). Removal of dung from hide pieces is affected by the action of cellulase, xylanase and laccase separately over 20-24 hours. Mixture of these enzymes removes dung in 6-8 hours demonstrating that synergistic activity is more effective than separate enzyme treatments. When commercial enzyme mixture or Coriolus versicolor or Aspergillus niger cultural broths were used to effect dung removal in tannery drums in a larger scale experiment, in some cases the removal of dung was observed within 1 hour by the help of the mechanical action and nonionic surfactant. The enzyme treatment did not affect the components of hide, such as collagen, hyaluronic acid and dermatan sulphate and it was found that enzyme treated leathers and control samples showed no differences in terms of their physical characteristics. Investigations in the mechanism of dung removal by spectrophotometry, chromatography and chemical techniques show that the enzyme treatments remove the dung from hides without changing the fundamental structure of the substrate. The enzymes probably attack the structural parts in lignocellulose, which are most susceptible to solubilising with enzymes: these attacks make small changes in the carbohydrate and lignin contents, but these changes are powerful enough for effective dung removal

To elucidate the reaction between collagen, condensed tannins and oxazolidine, two prodeiphinidin tannins have been studied: extracts from pecan nutshell pith and myrica esculenta bark. The tannin chemistry study showed pecan tannins are copolymers of catechin and gallocatechin with a ratio 1:6 and myrica tannins are prodeiphinidins with 40% of the structural units gallated. The average molecular weight was measured by GPC and the number average molecular weight of tannins was found to be 25 00-3000. The molecular structure of oxazolidine, 1 -aza-5-ethyl- 1,3-dioxacyc1o[3 .3.0] octane, was confirmed by IR, GC-MS and ‘H-NMR spectra. From NMR, the ratio between cis and trans conformations is nearly 1:1. Complete hydrolysis of oxazolidine is slow under weakly acidic or neutral conditions. The reaction of polyphenols with oxazolidine was modelled using simple phenols phioroglucinol, pyrogallol and resorcinol; the process was followed by chromatographic and NMR methods. The results show the reaction is second order: phloroglucinol has the highest reactivity. By using catechin and gallocatechin, it was shown that the cross-linking reaction of gallocatechins can happen between an A- ring and a B-ring, while for catechin, the reaction is only at the A-ring. Polyphenol polymer studies also support this result; more oxazolidine can be reacted with prodeiphinidins. The reaction of collagen with oxazolidine was studied; the reaction sites were determined using modified collagen. Few cross-linking reactions were found, which is supported by hydrothermal isometric tension (HIT) results. The reaction between polyphenol, collagen and oxazolidine was studied by HIT and it was found that the cross-linking is between collagen and tannins, which is responsible for the high stability of treated collagen. Based on this, organic combination tanning can be explained as an effect of covalent bonding, hydrogen bonding and hydrophobic bonding together, but the high shrinkage temperature is mainly due to the covalent bonding forming a complex matrix structure around the collagen fibres

A review across the periodic table of tanning effects of simple inorganic compounds reveals that many elements are capable of being used to make leather. But, if the practical criteria of effectiveness, availability, toxicity and cost are applied, the useflul options reduce to chromium (III) the benchmark orto titanium (IV) zucomum (V) iron (II/III) and aluminium (II) For mainly environmental reasons, alternative tanning agents to chromium are needed, However. none so far investigated match the all round properties achieved with chromium (III) salts. In tanning terms, the chemistry of titanium (IV) is dominated by the titanyl ion, TiO2, limiting its reactivity with collagen. An alternative approach to titanium tanning, using metastable titanium (III) salts as possible tanning agents, was investigated in this study. A method to determine the titanium content in leathers was developed. Complexes of Ti (III) were investigated using various spectroscopic techniques, including uv/vis spectroscopy, electron spin resonance, electron nuclear double resonance and nuclear magnetic resonance dispersion spectroscopies. The complexes used in subsequent tanning studies were based on titanium (III) citrate, gluconate and tartrate. However, in comparative trials with chromium (III) salts, the study highlighted that titanium (III) salts were not suitable for tanning collagen. Titanium (III) saks were found to be useflul in the production of semi- metal tamlages. The research was extended to investigate the hydrothermal shrinking of tanned collagen. Techniques such as extended x-ray absorption — fine structure and x-ray absorption near structure were used to investigate the interaction of chromium (III) tanning salts and titanium (III) complexes with collagen. The research demonstrated that the shrinking reaction is independent of the tannage. It involves instead the breaking of hydrogen bonds, rather than the breakdown of the tannin-collagen molecule. From this work, and a reappraisal of older work on the shrinking reaction, a new theory of tanning has been formulated based on co-operating units and the role of crystallinity in stabilising the collagen structure. The influence of the solvent is also discussed

Necin bark (1zadirach1a indica) contains a mixture of complex chemical components identified as: One procyanidin trirner Four dimers Cl Epicatechin-[4a-8j-epicatechin epicatechin. B1 Epicatechin- [4[3-8]-catechin, B2 Epicatechin- [43-8]-epicatechin, B3 Catechin-[4ct-81-catechin, B4 Catechin-[4a-81-epicatechin. Four well known monomers (+)-Catechin, (-)-Epicatechin, (+)-Gallocatechin, (-)-Epigallocatechin. Other compounds Quercetin, Kaempferol, Fisetin and Gallic acid These compounds were characterised by chromatographic and spectroscopic techniques, including by thiolytic degradation with toluene-a-thiol and using acetylated and methyl derivatives. Structural elucidation of the cleavage products was by ‘H-NMR. The backbone of the isolated compounds consisted mainly of a mixture of flavan-3-ol units with 2R- configuration. The purity of monomers, dimers and trimer was checked by HPLC on Lichrosorb RP8 column. The molecular weight distribution ranges between 250 and 5500 and the average molecular weight distribution was found to be 1550 by gel permeation chromatography. Gas chromatography-mass spectroscopy demonstrated the complex nature of NBT molecular masses consist of monomeric, dimeric and trimeric units of procyanidin B and C types respectively. IR and FT-IR spectroscopy results were consistent with the rest of the techniques used. The hydrothermal stability of neem bark tannin tanned and crosslinked hide powder and leathers was found to be paralleled to mimosa tannin extract. Studies of the physical properties of tanned and retanned leathers showed corn pai.ahility of micem bark tannins with mimosa tannin extract

This survey study evaluates the incidence of tanning in adults who use indoor gyms.

Kraft lignin degradation by a biomimetic system was investigated, using haemin and hydrogen peroxide, which mimics the catalytic mechanism of lignin peroxidase to produce phenolic compounds. The degradation products were identified using spectroscopic methods and gas chromatography-mass spectrometry. 2-methoxyphenol, 4-hydroxybenzaldehyde, vanillin and vanillic acid were produced and their formaldehyde polymerisation products were used for tanning collagen. The denaturation (shrinkage) temperature of collagen was raised to 80°C through hydrogen bonding interactions between the polymers and the protein. For dyeing of hide powder, the lignin degradation products were reacted with laccase (a polyphenol oxidase); 2-methoxyphenol gave the darkest colour. These products have potential to be used as raw materials for tanning and dyeing of animal skins. Therefore, this can add value to the industrial byproduct (Kraft lignin) and reduce its environmental impact. Polyphenols are the basic building blocks of natural skin and hair pigments: they can be polymerised to create versions of natural black, brown and orange melanins. These reactions can be catalysed by laccase; not only do they create colour, but also if they are conducted in the presence of collagen, the resulting pigment is bound to the leather in a covalent tanning manner. Therefore, the leather becomes coloured by a lightfast pigment, which is firmly fixed. It appears to be a feature of this type of stabilising mechanism for collagen, the creation of a polyphenol matrix around the triple helix, that it has the added benefit of actually strengthening the leather. Since every traditional process step effectively weakens collagen, especially tanning, this is the first chemical reaction that has been shown to reverse that effect. Leather tanning reactions between collagen and dihydroxynaphthalenes (DHNs) and oxazolidine have been investigated, using hide powder and sheepskin pickled pelt. This investigation showed that some DHNs have a tanning effect on collagen. The measurement of combined and cross-linked DHNs on collagen showed that 30-40% of 1,6- and 2,6-DHNs were fixed through covalent bonding. Shrinkage temperature of the leather changed little after the non combined DHNs had been removed from the leather, indicating that the high stability of the combination tanned leather comes from the covalent bonding formed between DHNs and collagen through oxazolidine.