Tri-«-octylphosphine oxide,

Modifications and improvements to the basic process have been made to reduce the quantity of waste products (21,22) in the wet chemical process, to recover HF, and to economically process low Ta, high Nb containing raw materials (23). Several alternative extraction media have been reported in the hterature. Most, except for tributylphosphate (TBP) (24) and tri- -octylphosphine oxide (TOPO) (25), have never been used in industry. 

Figure 10.3 shows a Co nanoparticle deposition prior to SiNW growth. The average size of the nanoparticles used in this deposition was 12 nm. The standard deviation was 5 nm. As shown in Fig. 10.3, no individual nanoparticles were detected by SEM. The nanoparticles were embedded in large amounts of organic solvents or hydrocarbons such as oleic acid (OA) and tri-octylphosphine oxide (TOPO). 

Liquid membrane enrichment coupled on-line with ion chromatography. Low molecular mass carboxylic acids in low concentrations in air or soil samples can be determined by ion chromatography coupled on-line to a selective enrichment system consisting of a supported liquid membrane, impregnated with tri- -octylphosphine oxide in di-n-hexyl ether [97-98]. The system allows the determination of these carboxylic acids at micromolar levels in the presence of interfering ions such as nitrite, chloride, sulfate, iron, and aluminum. 

A transient optical absorption study of charge recombination dynamics was recently reported on CD CdS with a crystal size of 5 nm (no details of the deposition were provided) [35]. Three different time constants for the decay of the transient absorption bleaching were measured (0.8 psec, 17 psec, and 800 psec) and were attributed to three groups of nanocrystals with specific defects. Tri-octylphosphine oxide (TOPO), a well-known passivating agent for CdSe nanocrystals that acts by binding to Cd, was found to increase the relative contribution of the 800-psec recombination, which was therefore attributed to volume recombination, since the TOPO is expected to reduce the relative contribution of surface recombination (represented by the two shorter time constants). 

The phosphorus compound may be used as a neat liquid or as a phase transfer agent between water and a hydrocarbon or other immiscible solvent. For a given alkyl group R, extracting efficiency follows the order OPR3 > OP(OR)R2 > OP(OR)2R > OP(OR)3. Amongst the phoshine oxides, tri- -octylphosphine oxide has been the most widely used and research into its use continues.135... 

Manchanda, V.K. Mohapatra, P.K. Extraction of plutonium(IV) with 1-phenyl-3-meth-yl-4-benzoyl-pyrazolone-5-one and tri- -octylphosphine oxide, Radiochim. Acta 60 (1993) 185-188. 

Four-membered ring complexes with cadmium are useful as precursors for the preparation of tri- -octylphosphine oxide (TOPO) capped materials. Thus, compounds 95 were efficient precursors to CdSe nanoparticles on thermolysis in TOPO C1996AM161, 1997CM523, 1998CC833, 1998CC1849, 1999CC2235>. 

Addition of tri- -octylphosphine oxide (TOPO), a proposed synergist, to the system works to improve the uptake of both actinide ions. Two plausible complexation stoichiometries have been reported for the synergistic effect of TOPO, suggesting the formation of two different extracted species (see Equations (56) and (57)) ... 

The third group is water-immiscible organic species with electron donor or acceptor properties, or solvating carriers. They include carbon-oxygen compounds (amides, ethers, ketones) phosphorus-oxygen compounds (tri- -butylphosphate (TBP), dibutyl-phosphate (DBP) or-phosphonate (DBBP) phosphine oxides (tri- -octylphosphine oxide (TOPO) phosphine sulfides (Cyanex 471) alkyl sulfides (dihexyl, diheptyl sulfides) nitrogen containing compounds (CLX 50), and so on [1-7, 81, 83]. All of them are known as selective extractants, but few of them are tested as carriers in LM processes. 

A similar concept was used for other environmental applications, for example, phenoxy acids, sulfonureas, phenolic compounds, and other environmentally important persistent pollutants [68, 76, 141, 143, 155-166]. Also, in the same manner, several drugs were enriched and determined in body fluids such as urine [144-146, 167-172] or blood [147, 156, 157, 173, 174]. A very advanced apphcation of SLM for analytical purposes, where transport process was based on simple diffusion with pH adjustment of aqueous phase, is the extraction of the basic drug, bambuterol, for pretreatment of plasma samples before analysis with capfflary zone electrophoresis (CZE) [147]. Bambuterol was used as a model substance in a separation system, where either 6-undecanone or a mixture of di- -hexyl ether (DHE) and tri- -octylphosphine oxide (TOPO) was used as membrane phase. It was possible not only to achieve a very low hmit of detection ( 50 nmol/1) but also to ensure the removal of salts from the sample. It helped to obtain the low ionic strength of the blood plasma samples and permitted subsequent sample stacking in the caphlary electrophoresis step. 

Separations research at the Rocky Flats Plant (United States) has found ways to significantly improve Pu recovery from HNO waste streams by using extraction chromatography. Several extractants, including TBP (tribu-tylphosphate), TOPO (tri- -octylphosphine oxide), DHDECMP (dihexyl N,N-diethylcarbamoylmethylenephosphonate), and CMPO (octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide) and their mixtures supported on Amberlite XAD4 and anion exchange resins (Dowex 1x4 and Amberlite IRA 938), were evaluated for their ability to remove low concentrations of plutonium from 7 M acid nitric [71-73],... 

In membrane extraction of metals, the mass transport of solute from one phase to another occurs by diffusion. It is controlled by phase equilibrium and the resistances of boundary layers in two phases and the membrane material. Both types of materials are used for membrane extraction and stripping, hydrophilic and hydrophobic, and composite hydro-philic/hydrophobic barriers are also developed to avoid the membrane solubilization [122,123]. To enhance separation, the reactive liquids that induce chemical reaction with one of the separated species can be used. In membrane SX of metals, extracting agents, such as tri- -octylphosphine oxide (TOPO), di(2-ethylhexyl)phosphoric acid (D2EHPA), and n-octyl(phenyl)-A,A-diisobutylcarbamoylmethylphosphine oxide (CMPO), and commercial reagents like CYANEX 301, CYANEX 923, LIX622, and LIX622N are applied. 

Solvent extraction of wet process uranium is now commercially feasible - most of the available processes use phosphate esters, for example, tri-octylphosphine oxide and di-2-ethylhexyl phosphate in kerosene (Chapter 12.11). Significant quantities of rare earth elements such as La and Th are also present, but commercial extraction of these is not yet economic [10,11]. 

Kulkami, PS. (2003) Recovery of uranium(VI) from acidic wastes using tri- -octylphosphine oxide and sodium carbonate based liquid membranes. Chemical Engineering Journal, 92,209-214. 

Similarly, CdSe nanoparticles have been functionalized using ligand exchange reactions [62]. The nanoparticles were stabilized by the tri- -octylphosphine oxide... 

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