Kinetics of Mn(II) extraction by D2EHPA

• Published in: Hydrometallurgy Vol. 69; no. 1; pp. 145 - 156
• Main Authors: Biswas, R.K, Mondal, M.G.K
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2003; Elsevier
• Subjects: Applied sciences; D2EHPA; Exact sciences and technology; Extraction kinetics; Hahn cell; Hydrometallurgy; Kerosene; Lewis cell; Metals. Metallurgy; Mn 2; Production of metals; Production of non ferrous metals. Process materials; Sulphate medium; L.C; h.t.r; w.r.t; Kerosene; D2EHPA; I; HA 2; Lewis cell; H 2A 2; RDC; S; Mn 2; HA; Hahn cell; H.C; Sulphate medium; l.t.r; Extraction kinetics; Recovery metals; Manganese II; Experimental study; Solvent extraction; Chemical reaction kinetics; Hydrometallurgy
• ISSN: 0304-386X; 1879-1158
• DOI: 10.1016/S0304-386X(03)00004-5

The kinetics of forward extraction of Mn(II) from 0.1 M SO 4 2− medium by di-(2-ethyl hexyl) phosphoric acid (D2EHPA) solution in kerosene have been investigated by the Lewis (L.C.) and Hahn cell (H.C.) techniques. For kinetic data treatment, both pseudo-rate constant, ‘ q’ or ‘rate/area’ and flux, ‘ F’ methods have been applied. The empirical rate equations have been derived. Results have been compared among themselves and other published works on Mn(II)–D2EHPA systems. The rate constants obtained from the ‘ q’ and ‘ F’ methods differ in magnitude and units and an explanation of this has been given. An analysis of the rate equations obtained from the Lewis cell technique suggests that the reaction: Mn 2++HA 2(i) −→[Mn(HA 2)] (i) +occurring at the interface is the slowest. High activation energy, E a, in the lower temperature region (l.t.r.; 53 kJ mol −1) supports the above mechanism. But the low E a value in the higher temperature region (h.t.r.; 10 kJ mol −1) suggests a diffusion controlled reaction at the interface. In the Hahn cell experiments, E a never exceeds 12 kJ mol −1 and so the process is entirely diffusion controlled in this cell at any temperature. The rate constant obtained from the Lewis and Hahn cell techniques using either ‘ F’ or ‘ q’ method differs widely ( k L.C.=100 k H.C.) and an explanation has been given.