Common tormentil tannins as tanning material for leather processing

У роботі представлені результати дослідження властивостей танідів, отриманих з кореня перстачу прямостоячого (Potentіlla erecta) і властивості ними видублених шкір. Визначено, що ці таніди відрізняються високою спорідненістю до колагену. Шкіра, видублена цими танідами відрізнялася коричнюватим забарвленням, лицьовою поверхнею без стяжки, високою міцністю при розтягуванні й низьким відносним видовженням. Температура зварювання шкір досягала 73 oС.В работе представлены результаты исследования свойств таннидов, полученных из корней Лапчатки прямостоячей (Potentilla erecta), и свойства ими выдубленных кож. Определено, что эти танниды отличаются высоким сродством к коллагену. Кожа, выдубленная этими таннидами, отличалась коричневатой окраской, лицевой поверхностью без стяжки, высокой стойкостью при растяжении и малым относительным удлинением. Температура сваривания кож достигала 73 oC.Presented research devoted for investigation of Common tormentil (Potentilla erecta) tannins properties and tanning peculiarities. It was established that tormentil tannins have high affinity to collagen. Leather tanned with tormentil tannins distinguished by brownish grain colour, grain was not shrunk, and it had high tensile strength but low relative elongation. Shrinkage temperature of leather tanned with tormentil tannins reaches 73.6oC, and it is almost same like after tannins with modified vegetable tannins or synthans

Current trends in leather science

Abstract In preparing the second edition of ‘Tanning Chemistry. The Science of Leather.’, the literature was updated and the content was revised and reviewed. Here, the new findings are presented and discussed. Notable developments include the necessary rethinking of the mechanism of sulfide unhairing because of new understanding of the aqueous chemistry of sulfide species. Revision upwards of the value of the second pKa for sulfide species ionisation means that S2− cannot exist in an aqueous medium, so the unhairing species in hair burn reactions is HS−. Although the technology remains the same, this means the mechanisms of associated reactions such as immunisation must be revised. Rawstock preservation has benefitted from studies of the potential role of materials from plants which accumulate salt, but which also contribute terpene compounds. There is also further discussion on the continuing issue of chromium (VI) in the leather industry. The application to processing of new solvents, ionic liquids and deep eutectics, is the coming technology, which offers transforming options for new chemistries and products. Renewed interest in vegetable tanning and methods of wet white processing are current trends. Also, within the topic of reagent delivery is processing in a solid medium of plastic beads. Graphical abstrac

Immunizacja wełny metaglinianem sodu

Since the environmental requirements for leather manufacture as well as for other industry branches are becoming stricter, investigations of unhairing have been directed towards conditions of the process which allow the saving of hair: enzymatic unhairing or unhairing with hair immunization conventionally achieved by using lime and sodium sulphide. The problem is that lime forms a big quantity of liquid waste which contains lime sludge polluted by sulphides and protein degradation products. The research is devoted to the replacement of Ca(OH)2 as hair immunization material with some other soluble non-hazardous material with a similar immunization effect. The preliminary tests showed that alkaline sodium aluminate suits this purpose very well. Its immunisation efficiency increases with prolonged treatment duration and increased concentration of the treatment solution. Treatment with 20 g/l of sodium silicate solution for 3 h allows to reach a high immunization ability almost the same as that of calcium hydroxide under the same conditions. The immunisation effect lasts when the pH is approx. 13.Ponieważ normy dotyczące ochrony środowiska w przemyśle skórzanym, jak również w innych gałęziach przemysłu stają się coraz bardziej restrykcyjne, badano immunizację wełny wodorotlenkami wapnia i potasu oraz metaglinianem sodu, badając poziom degradacji wełny po obróbce. Efekt immunizacji został oszacowany na podstawie zmian utraty masy wełny i zawartości azotu w roztworze. Potwierdzono, że metaglinian sodu jest skutecznym środkiem immunizującym. Skuteczność immunizacji metaglinianem sodu zwiększa się wraz z wydłużeniem czasu obróbki i zwiększeniem stężenia roztworu

Alkali-free method of hide preparation for tanning

Usually, beamhouse processes are carried out by varying a medium from strongly alkaline (unhairing-liming) up to strongly acid (pickling). This study is designed to develop a preparation of hide for tanning via processes that avoid a sharp change of hide pH. Enzymes active in acid medium are employed for hide unhairing in a buffer system containing 2.5% acetic acid and 0.3% sodium acetate. An oxidative treatment with peracetic acid then allows the complete removal of residual hair and scud. During both processes, unhairing and oxidative treatment, the opening of the derma structure occurs: 13.3-14.6g of non-collagen proteins are removed and amount of dermatan sulphate decreases by 35%. The hide obtained can be chromed directly after the above processes and subsequent treatment with sodium chloride solution omitted conventional pickling. The pH of the hide varies in the range of 8.3-3.7 during the processes of preparation for tanning

Application of Fourier transform infrared (FTIR) spectroscopy in the characterization of tannins.

A review of vibrational frequencies reported for tannin molecules is provided to create a database with typical fingerprints for different types of tannins. This will provide researchers working on vibrational spectroscopy applications and technicians a fast, easy, and reliable method to assess the quality and authenticity of these compounds, both extracted in laboratories and provided from commercial sources. The widespread use of these compounds has highlighted the need for a systematic characterization of the vibrational frequencies and molecular fingerprints for their identification and discrimination. According to our knowledge, this is the first systematic collection of typical peak frequencies for tannins, which can be applied in several research fields and technological applications