Optimization of two-low salt chrome tanning processes without float

Abstract

The aim of this study was to develop at pilot plant level two systems of pickle-tanning that would reduce both the amount of waste water and its content in chrome and chlorides while obtaining leathers that are commercially acceptable. In the first one, the effect of the variation of the final tanning temperature as well as the system of adding the basificant in the formulation of a chrome tanning without float were studied. A 87 percent reduction of the residual float was obtained with this system. The amount of chrome in wastewater was reduced by 96 percent in this study as compared to taht of a tradtional tanning process. The reduction of chlorides in all the tanning tests without float was maintained at around 94 percent. In the second one, the pickle process was carried out without float and with low salt addition, and the inorganic acids were replaced by a sulphoaromatic acid. The effect of the variation of the final temperature was studied in the tanning, as well as the type of basification used for the chrome exhaustion in the residual float. A 88 percent reduction of the residual float was obtained with this system, as well as a 99 percent reduction in chrome content in wastewater and a 93 percent reduction in chlorides content in wastewater.