Chrome Tanning Under The Condition Of Supercritical Carbon Dioxide Fluid

A new supercritical carbon dioxide fluid equipment was developed first time for chrome tanning process of leather manufacture. The experiment results showed that using this equipment the chrome tanning process was simplified without decreasing the quality of leather, the environment pollution was minimized and "zero release" which was promoted continuously was really achieved.The factors affecting chrome tanning in supercritical carbon dioxide fluid were temperature, pressure, mechanical action, time, initial pH, entrainer and chrome dosage, which had some difference from traditional methods. The chrome tanning behavior in supercritical carbon dioxide fluid was determined by the shrinkage temperature, chrome content in wet blue, the color of the leather and the grain state etc, and then sought the optimum conditions in chrome tanning in supercritical carbon dioxide fluid.In addition, as a new non-waste method the supercritical carbon dioxide fluid has its great potential properties on leather manufacturing, for example, fiber's porosity, area, thickness and degreases effects which are different from traditional methods, especially the characteristics of area yield and thickness were better than traditional methods.Physical properties and sense performances of the finished leather which chrome tanned by supercritical carbon dioxide were match or overmatch the properties of the traditional tanning.The mechanism of chrome tanning in supercritical carbon dioxide fluid medium also discussed primarily. The reactive groups involved has been studiedusing modified collagen such as methylated collagen and deaminated collagen, then these pretreated pickled hides were chrome tanned under water and supercritical carbon dioxide fluid mediums and determined the shrinkage temperature and chrome content of the chromed tanned leather. The results showed that the carboxyl groups rather than amino groups of the collagen fibers were the main reactive centers for chrome tanning in supercritical carbon dioxide fluid, which also approving that the method can put into practice.The present study has made a practical application of supercritical carbon dioxide fluid to chromium tanning and especially established a foundation for further understand of supercritical carbon dioxide fluid on leather making, and that the chemical theory of chromium tanning might be better acquired.