1. Extraction rate of Ho3+ ions from an aqueous solution to D2EHPA in cyclohexane
M. Wojnicki 1*, M. Luty-Błocho1, K. Kołczyk1, and P. Żabiński AGH University of Science and Technology, Faculty of Non-Ferrous Metals, Laboratory of Physical Chemistry and Electrochemistry, 30 Mickiewicza Ave., Cracow, Poland *
BR2018 – 2nd conference on Bauxite Residue Valorisation and Best Practices

2. Introduction
Taking into account an unique magnetic properties of metals belonging to Rare Earth Elements (REE), the new methods for their recovery and separation are developed. For this purpose, methods like separation in magnetic field or extraction are applied and investigated. The separation in magnetic field is promising way, because uses the differences in magnetic properties of rare earth metal ions to achieve separation by attraction or repulsion in an inhomogeneous magnetic field [1,2]. However, this method has its limitation even if related with the necessary equipment. The extraction method seems to be more practice. In the literature, there are study relates to extraction of REE ions using cation (carboxylic acid, phosphorous acids), chelating, solvating and anion exchangers.

3. Results
Fig. 1. UV-Vis spectrum of A) water phase and B) organic phase containing Ho(III) after eqiulibirum achive

4. Results
Simple kinetic model was used do describe kinetic of the studied process.
To registered kinetic curves (fig. 3), integral form of proposed proces model for was fitted.
Fig. 3. Extraction kinetic curves

5. Results
Thanks to that it was possible to determine the distribtiution ratio as well as extraction kinetics. It was observed that the distribtuion ratio (D) is independent of the temperatur in the tested range. Morover, the D-1 is directly proportional to Ho(III) initial concentration.
Fig. 4. Influence of Ho(III) initial concentration on distribution ratio.

6. Conclusions
It was found that in the studied range of temperature from 20 to 45oC there is no changes in distribution ratio.
Distribiution ratio depends on initial concentration of Ho(III) in water phase and varied in the range from 1.3 to 117 for the initial concentration of Ho(III) in the range from 0.1 to M.
There is strong impact of initial concentration of Ho(III) ions on the observed extraction rate.
The observed extraction rate varied in the range from min-1 to min-1 when the initial concentration of Ho(III) ions is varied in the range from 0.1 to respectively.

7. Financial suport
This work was supported by: the Polish National Science Center
under grant No. 2014/15/B/ST8/01528

8. Thank you for your attention