Separation Iron(III)-Manganese(II) via Supported Liquid Membrane Technology in the Treatment of Spent Alkaline Batteries.

Francisco J Alguacil,Félix A Lopez

doi:10.3390/membranes11120991

Abstract

In this paper, the transport of iron(III) from iron(III)-manganese(II)-hydrochloric acid mixed solutions, coming from the treatment of spent alkaline batteries through a flat-sheet supported liquid membrane, is investigated (the carrier phase being of Cyanex 923 (commercially available phosphine oxide extractant) dissolved in Solvesso 100 (commercially available diluent)). Iron(III) transport is studied as a function of hydrodynamic conditions, the concentration of manganese and HCl in the feed phase, and the carrier concentration in the membrane phase. A transport model is derived that describes the transport mechanism, consisting of diffusion through a feed aqueous diffusion layer, a fast interfacial chemical reaction, and diffusion of the iron(III) species-Cyanex 923 complex across the membrane phase. The membrane diffusional resistance (Δm) and feed diffusional resistance (Δf) are calculated from the model, and their values are 145 s/cm and 361 s/cm, respectively. It is apparent that the transport of iron(III) is mainly controlled by diffusion through the aqueous feed boundary layer, this being the thickness of this layer calculated as 2.9 × 10−3 cm. Since manganese(II) is not transported through the membrane phase, the present system allows the purification of these manganese-bearing solutions.

Highlights

Recycling is an issue of increasing necessity in the 21st century which is caused, among other factors, by the decrease and depletion of certain raw materials, and more stringent environmental pressures about the discharge of contaminants.One example of materials to be recycled are alkaline batteries, which contain valuable metals that can be recovered and reuse
The extractant used in the investigation was Cyanex 923 (Solvay, Brussels, Belgium, commercially available phosphine oxide), which was dissolved in Solvesso 100 (Exxon Chem Iberia, Barcelona, Spain, aromatic diluent) in order to obtain an adequate range of extractant concentrations to the transport experiments
The extraction of iron(III) by the phosphine oxide was based on a solvation reaction [17], represented by the equilibrium [18,19]: nLorg + FeCl4−aq + Ha+q ⇔ HFeCl4·nLorg where L represented the extractant molecule, n was an stoichiometric factor, and the subscripts aq and org referred to the equilibrated aqueous and organic phases, respectively

Summary

Introduction

Recycling is an issue of increasing necessity in the 21st century which is caused, among other factors, by the decrease and depletion of certain raw materials, and more stringent environmental pressures about the discharge of contaminants.One example of materials to be recycled are alkaline batteries, which contain valuable metals that can be recovered and reuse (allowing one to gain a further profit from the recycling process). CENIM-CSIC developed investigations about the use of ammonium carbonate processing in the recycle of zinc-bearing materials such as electric arc furnace (EAF) flue dusts and Waelz oxides [1,2,3]. The mass yielded after breaking of the battery case is subjected to a leaching process in ammoniacal ammonium carbonate solutions. Zinc is recovered from the leachate, whereas the solid residue contains iron and manganese (VII) compounds. This residue is treated via leaching in HCl medium, yielding a solution containing Fe(III) and Mn(II), since in the operational conditions, manganese(VII) oxidizes chloride ions and, it is reduced to Mn(II). The use of liquid membranes, supported liquid membranes technologies, can be of interest due to the economical and operational advantages that these technologies possess

Methods

Results

Conclusion