A rotating diffusion cell (RDC) has been used to study the kinetics
of extraction of the transition metals cobalt (II), nickel (II), copper
(II) and zinc (II) from sulphate solutions into either of two extractants
held in n-heptane; di-(2-ethylhexyl) phosphoric acid (D2EHPA) or di-(2-
ethylhexyl) dithiophosphoric acid (D2EHDTPA). The metal concentration was
10 mM and the aqueous pH was held at 4.5. The extractant concentration was
varied between 0.015 to 0.4 M. In the case of cobalt extraction by D2EHPA,
the metal concentration and the pH were varied Different diluents and
modifiers were also studied.The rate of extraction by D2EHDTPA was found to be faster than D2EHPA.
A comprehensive mathematical model, based upon established two film
theory, was developed and used to describe the above experimental results.
The model was also used to predict values of the important parameters. ... These values compared well with those found by other authors but using
quite different experimental techniques.
OS4 In the case of cobalt extraction by D2EHPA, the more polar diluents
lowered the initial rate. The overall model predicts such behaviour where
the rate is also dependent on the partition coefficients of the extractant.
Finally, the theory of the RDC allows the prediction of the diffusion
layer thicknesses, this information together with the reaction zone thickness
is used to explore the influences of diffusion and chemical reaction on the
overall transfer process. The diffusion processes are calculated to be the
most important of the two. This is especially so for the D2EHDTPA systems. / University of Bradford Scholarship Award
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/5025 |
| Date | January 1988 |
| Creators | Patel, Hamantkumar Vasudev |
| Contributors | Hughes, M.A. |
| Publisher | University of Bradford, Postgraduate School of Studies in Chemical Engineering, |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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