This project investigated the feasibility of derivatizing a montmorillonitic clay, with commercial liquid extractants to obtain a material with the metal extraction properties of the liquid extractant that can be applied directly into metal leaching circuits. The intercalation of several commercial liquid-liquid extractants: alkylphosphoric acid (DEHP A), carboxylic acid (Versatic 1 0), l3-hydroxyoxime (Acorga M-5640), substituted hydroxyquinoline (Kelex 100) and l3-diketone (LIX 54) was carried out. The alkylphosphoric extractant, DEHPA, was taken as a model for obtaining data on parameters that influence the adsorption of the molecule onto the clay. The variables studied were the kinetics of adsorption, effect of composition of the selected solvent media (EtOHIH20) and interlayer cations both inorganic (Na+, Ca2+ and Cu2+) and organic (alkylammonium). Optimum conditions obtained for the alkylphosphoric extractant were then applied to the other extractants. X-ray powder diffraction and FTIR characterisation confirmed that the extractant molecule was adsorbed in the interlayer spaces of the clay. The adsorption process showed fast kinetics (five to fifteen minutes), was strongly related to the water content of the solvent media and to the nature of the interlayer cation. The mechanisms for the adsorption of the extractant on the homoionic inorganic and organic clays are discussed. All the intercalated materials extract copper and nickel ions from solution and the metal loadings are similar to materials such as Solvent Impregnated Resins (SIR). The loading isotherms and maximum loading capacities indicate the formation of both 2: 1 and the charged 1: 1 extractant:metal complexes. Extractant losses from the alkylphosphoric intercalated montmorillonites during use compare very favourably with similar liquid-liquid systems or SIR's containing the same extractant. Attempts to agglomerate the resulting intercalated material to obtain pellets between 1 and 2 mm in diameter were made using different inorganic and organic polymeric binders. The most effective binder was a crosslinked polyester obtained by in-situ polymerisation on the clay. The resulting clay-extractant pellets retained their metal extraction properties with acceptable mechanical properties, but the process requires further optimisation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:394138 |
| Date | January 1999 |
| Creators | Romero, Jose Ramon Rus |
| Publisher | University of Hertfordshire |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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