Recovery of Cr(III) from Tannery Spent Chrome Liquor for Reuse

This paper embodies details on the extraction behavior of Cr(III) along with Al(III), Fe(III), Mg(II), Mn(II), Co(II), Ni(II), and Cu(II) from hydrochloric acid media employing the Cyanex 301-toluene system. All of these metals, except Cr(III), Mg(II), and Mn(II), are extracted into the organic phase. This property of the extractant has been used to separate Cr(III) from the binary mixtures. The partition data have been extended onto spent chrome liquor, and this waste has been treated in such a manner so that it becomes suitable for use in trivalent plating baths. The hydrolytic stability and recycling capacity has been reported. Because the concentration of Cr(III) in the waste is much lower than that required for chromium depositions in Cr(III) plating baths, a concentration step using MgO as a precipitating agent has been appended. To summarize, this paper envisages a new approach to tannery waste management that focuses on treating spent chrome liquors using a solvent extraction technique in such a manner that the waste becomes suitable for use in trivalent plating baths. This would not only help abate pollution but also recover the metal in a pure form.