PROCESS FOR CONCENTRATING A SOLUTION OF TARA EXTRACT AND APPLYING THE SAME WHEN PROCESSING NATURAL HIDES

The invention relates to a process for concentrating the Tara extract solution, in order to obtain a concentrate, as well as to a process for ecologically processing the bovine hides. According to the invention, the process consists of a succession of stages of pre-filtration and micro-filtration with a membrane of cellulose acetate, followed by a stage of concentration of the obtained permeate, by nano-filtration with a regenerated membrane, made of cellulose, at a pressure of 2...10 bar and by reverse osmosis with a membrane of nitro-cellulose, at a pressure of 5...15 bar. The claimed concentrate comprises 74...75% by weight, tannin, and has a tannin : non-tannin ratio of 3 : 1. The claimed process consists in pretanning, for 90 min, the bovine hides depickled at a pH=5 in a water float, where 3...7% solution of concentrated Tara was added, after which a fixation with formic acid at a pH=3.7 follows for 120 min.