Northampton Electronic Collection of Theses and Research

The influence of power ultrasound on leather processing

Xie, J. (1998) The influence of power ultrasound on leather processing. Doctoral thesis. University of Leicester.

Item Type: Thesis (Doctoral)
Abstract: The effects of ultrasound (38 kHz, 1.3 W cm2) on the dyeing, fatliquoring and tanning of leather have been investigated and the mechanisms whereby ultrasound influences these processes were elucidated. Compared with a conventional process, ultrasonic dyeing can either shorten the dyeing time by 40-70% or facilitate low temperature dyeing. This remarkable enhancing effect has been attributed mainly to an increased diffusion coefficient (D) of dyestuff in the presence of ultrasound. It was found that sonication is more effective in the initial phases than in the late phases of the dyeing process. Application of ultrasound during the fatliquoring process or simply in the preparation of fatliquors resulted in an increase of leather fat contents (up to 40%), especially in the inner corium layer, indicating an improved penetration. This can be partly attributed to a reduction of particle size by 20-30%. In contrast to dyeing, ultrasound was found to be more effective later rather than earlier in the fatliquoring process. Chromium and aldehyde tanning processes were accelerated only marginally (1 0%) but the mimosa tanning process was speeded up significantly (by up to 100%) by using ultrasound. Leathers tanned in the presence of ultrasound had shrinkage temperatures 3-5°C higher than conventionally processed controls. A more even chromium distribution and less chromium leaching were obtained after using ultrasound. The results showed that ultrasound can increase the dispersion rate and the available tannin content (by 7%) of mimosa, as well as reducing its particle size by 50%. It was also found that ultrasonic treatment can prevent mould from growing on mimosa tanned leathers. It is concluded that ultrasound is more effective in a process which involves a colloidal rather than a true solution system. The prevailing effects of ultrasound on the former processes are to increase the diffusion coefficient and reduce the aggregation. This is due to cavitation
Additional Information: This University of Northampton thesis was validated by the University of Leicester
Subjects: T Technology > TS Manufactures > TS967 Chemistry and science of leather
T Technology > TS Manufactures > TS965 Leather technology
Creators: Xie, Jianping
Department: School of Applied Sciences (to 2009) > Leather Technology (to 2009)
Faculties, Divisions and Institutes: University Faculties, Divisions and Research Centres - OLD > School of Applied Sciences (to 2009) > Theses (to 2009)
Date: 1998
Date Type: Completion
Number of Pages: 254
Language: English
Status: Unpublished
Institution: University of Leicester
URI: http://nectar.northampton.ac.uk/id/eprint/2662

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