ISOLATION AND CHARACTERIZATION OF A LOW-AFFINITY CHROMIUM(III) COMPLEX IN CHROME TANNING SOLUTIONS

A mixture of aquo complexes of chromium(III) is used for tanning. Thes e complexes vary in their nature and reactivity to the protein. The pr esent investigation deals with the understanding of the nature of the chromium(III) complexes present in spent chrome tanning solutions. An ion exchange chromatography technique has been employed for the isolat ion of the various complexes from fresh and spent tanning solutions. T hese studies indicated the presence of low affinity species to the ext ent of 45% of the total chromium in the spent solution. The low affini ty chromium(III) complex was characterised by W-visible spectroscopy, charge per atom, charge per species, degree of polymerisation and hydr oxyl per chromium and has been established to be a cyclic tetrapositiv e tetrameric species with unusual reactivity.