Metal ions, extraction from

ESI has been used to study the effect of the basicities of the side arms on the abilities of these lariat ethers to extract metal ions from solution. A series of compounds of structure 9 were studied and the authors conclude that the lariat ether with the least basic side arm binds best to the smaller cations (Table 6). Specifically for Li+, it was found that it is best bound to the lariat ether with the ester side arm. It is proposed that electrostatic repulsion of the lariat ether side arm and the electron-rich jt cloud of the adjacent aromatic ring play a dominant role in determining cation selectivities. The least basic side arm has lower electron density and thus these compounds have smaller cavity sizes and are more selective for smaller ions. ... 

A metal chelator, soluble only in organic solvents, can extract metal ions from aqueous solutions, with selectivity achieved by adjusting pH. 

Cation-exchange resins extract metal ions from aqueous solutions by forming the metal salt of the acidic functional groups on the resin. This type of reaction can be represented by the following simple equation... 

Table 4.1 On the possibility to extract metal ions from aqueous media by a mixture of proteinoids or/and solid alkaline earth carboxylates or aminocarboxylates, representing the state of matters after step 2. Required minimal differences of electrochemical hgand parameters (column 5) were calculated using Eq. 4.1...

The conditions for extracting metal ions from hydrochloric acid solution into ethyl ether as ion-association complexes are shown in Figure 20.7. 

The solid supported extractants can be employed in fixed bed contactors to extract metal ions from solutions. Other geometries include slurry extractors and moving bed adsorbers. We consider a fixed bed geometry. In this case the following mass transfer processes may be present (1) interpellet mass transfer, which refers to the diffusion and mixing of metal ion in fluid occupying the spaces between pellets (2) interphase mass transfer, which is the transfer of metal ion across the fluid peUet interface and (3) intraparticle mass transfer, which is the diffusion of metal ions in... 

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