The syntheses and characterisation of di(cyclohexylmethyl),
di(2-cyclohexylethyl), di(2-methylcyclohexyl) and di(4-methylcyclohexyl)
phosphoric acids; cyclohexylmethyl phosphonic acid monocyclohexylmethyl
ester, di(cyclohexylmethyl), di(4-methylcyclohexyl), di(4-tert-
butylcyclohexyl), di(3-methylcyclohexyl), di(3,5-dimethylcyclohexy)
and di(2-methylcyclohexyl) phosphinic acids are reported.
Problems encountered and how they were resolved during the
preparation of the above organophosphorus acids are reported and
discussed in detail.
These acids are then evaluated as potential hydrometallurgical
extractants, for the separation of cobalt from nickel in acid leach
liquors, and compared with two commercially available extractants,
namely di(2-ethylhexyl)phosphoric acid (D2EHPA) and di(2,4-4-
trimethylpentyl)phosphinic acid (Cyanex 272).
The effects of variablest such as metal feed solution concentration,
extractant concentration, diluent, modifier and temperature are
examined experimentally in order to determine which factors are important
for optimisation of an extraction system.
The extraction characteristics for each acid as a function of
pH are presented graphically and the pHO 5 values, distribution
coefficients and separation factors are calculated.
The dialkylphosphinic acids are found to exhibit much greater
selectivity, for cobalt over nickel, than the dialkylphosphoric
acids.
It is postulated, that steric crowding of the phosphorus atom,
by the hydrocarbon groups attached to the phosphorus, increases the
selectivity of an extractant. This effect is particularly apparent
in the dialkylphosphinic acids with di(2-methylcyclohexyl)phosphinic
acid giving the best selectivity; much better than the commercially
available Cyanex 272.
Several of the dialkylphosphinic acids, evaluated as extractants
in this thesis, are protected by a British Patent Application. / Science and Engineering Research
Council
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/4395 |
| Date | January 1987 |
| Creators | Chahal, Surinder P. |
| Contributors | Maitland, Derek J. |
| Publisher | University of Bradford, Postgraduate School of Studies in Chemistry |
| 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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