Two-stage Temperature Change Chrome Tanning: A More Sustainable Tanning Process

Abstract

Under the guidance of molecular simulation of Cr(III) species inwater solution, a novel chrome tanning process, the two-stagetemperature change chrome tanning, was developed. In stage I,the pickled cattle hide was first tanned by a small amount ofchrome tanning agent under room temperature to obtain basichydrothermal stability. Then, in stage II, the pre-tanned wet-bluewas tanned again under a high temperature (? 60°C) to enhancethe reactivity of Cr(III) with collagen fibers. The shrinkagetemperature of crusts, the absorptivity of chrome tanning agentand fatliquoring agent, the mechanical property and surfacemorphology of crusts were characterized to evaluate the tanningeffect. The results showed that when the dosage of chrometanning agent in two stages was 2 wt% (tanned under roomtemperature) and 1 wt% (tanned under 60°C), respectively, thebest performances of crust were achieved. In these conditions,the shrinkage temperature of crust was 104.6°C. Thecomprehensive absorptivity of chrome tanning agent reached upto 96.3%. The absorptivity of fatliquoring agent in wet-blue was90.2%. The mechanical property and grain fineness of the crustwere comparable to those of conventional chrome tanned crustwith 6 wt% chrome tanning agent. As a result, an efficient andmore sustainable chrome tanning process with less offer ofchrome tanning agent was achieved.