The extraction of Co2+ from a 0.1M ionic strength aqueous phase (Na+, CH3COOH) of pH=5.1 was studied using thenoyltrifluoroacetone, HTTA, in eight different solvents and HTTA+trioctylphosphine oxide,
TOPO, in the same solvents. A comparisons of the effect of solvent dielectric constants on the equilibrium constant shows
a synergism as a result of the increased hydrophobic character imparted to the metal complex due to the formation of the TOPO
The extraction of Co2+ from aqueous 0.1M acetate buffer by thenoyltrifluoroacetone (HTTA) and 8-hydroxyquinoline (HQ) and by a mixture of HTTA+phen and HQ+phen in benzene has been studied at various temperatures allowing for elucidation of the thermodynamics of extraction in the cases investigated.
The thermodynamics of the extraction of Eu3+ by thenoyltrifluoroacetone (HTTA) and by mixtures of HTTA and bidentate amine bases such as 2,2-dipyridyl (Dipy) and 1,10-phenanthroline (Phen) in benzene from an aqueous phase fixed to 0.1M ionic strength (NaClO4), pH 3.9, has been investigated. Phenanthroline forms both the Eu(TTA)3·Phen and Eu(TTA)3·2Phen species, which are much stronger than the dipyridyl complexes. The diluent effect on the extraction is also studied.
The extraction of Co3+ from 0.1M aqueous acetate medium buffered to pH 5.3 by thenoyltrifluoroacetone (HTTA) in benzene and by 8-quinolinol (HQ) also in benzene at various temperatures has been studied. The species formed were Co(OH)2 (TTA)·(HTTA)2 and Co(Q3)·2HQ, respectively. 1,10-phenanthroline (Phen) as a base was also mixed with HTTA to form the species Co(OH)2(TTA)·(HTTA). Phen and Co(OH)2 (TTA)(HTTA)·2Phen. No synergism was observed upon the addition of Phen to HQ.
The extraction of Co2+ by mixtures of acetylacetone (acac) and either pyridine (Py), benzylamine (ba), triethylamine (tea) or tripyridylamine (tpa)
bases in xylene solvent was investigated from an aqueous phase containing salts of LiCl, NaCl, KCl, RbCl and CsCl in concentrations
varying up to 3M. The different hydration properties of the alkali metal cations is show to affect very slightly the synergistic
solvent extraction of Co2+. This result, together with previously obtained thermodynamic data indicating the nonexistence of water molecules in the
extracted synergistic species, may explain the fact that these salts have no effect on the extraction of Co(acac)2 (N-base)2.
The extraction of Co2+ by a mixture of acetylacetone (acac) and pyridine (py) from an aqueous phase of varying ionic strengths has been investigated.
The extraction studies were done at different temperatures in order to determine the effect of changes in the ionic strength
on the free energy ΔG, enthalpy ΔH and entropy ΔS of the synergistic reaction.
The stability constants of UO
-squarate complexes are measured at ionic strengths of 0.05M, 0.06M, 0.075M, 0.09M, 0.1M (squaric acid-perchloric acid) using a solvent extraction method at a pH of 1.1 and a temperature of 25 °C. The extractant used is dinonylnaphthalenesulfonic acid in n-heptane. The aqueous phase was made of a mixture of squaric and perchloric acid and233U radio tracer. The stability constants of squarate complexes of UO
is seen to decrease linearly with the square root of the ionic strength.
The squarate complexes of Eu3+, Tb3+ and Tm3+ in aqueous solutions of 0.05M, 0.075M and 0.1M ionic strength are studied using the solvent extraction method. Effects of
changes in the ionic strength on the stability constants of the complexes formed are discussed.
Extraction of Eu3+ from 0.1M aqueous perchlorate medium by thenoyltrifluoroacetone (HTTA) and by mixtures of HTTA and tributylphosphate (TBP), HTTA and triphenylphosphine oxide (TPPO), HTTA and trioctylphosphine oxide (TOPO) and HTTA and triphenylarsine oxide (TPAsO) has been studied at various temperatures allowing for the elucidation of the mechanism of extraction in each case and a comparison between the various bases.
Authors:A. Kandil, A. Attia, A. Sharief, and A. Leilh
Two field experiments were conducted at the Experimental Station of the Faculty of Agriculture, Mansoura University, Egypt, during the 2006/2007 and 2007/2008 seasons. The results showed that a gradual increase in soil water tension from 24 centibars (cb) (5588.25 m3/ha), i.e. 56.3% field capacity to 36 cb (2634.49 m3/ha), i.e. 41.% field capacity, significantly decreased the average onion bulb weight (g), bulb diameter (cm), bulb length (cm), total bulb yield (t/ha) and marketable bulb yield (t/ha) and significantly reduced the total percentage loss after 2, 4 and 6 months in both seasons. Conversely, this increase in water tension significantly amplified the culled bulb yield (t/ha), bulb dry matter (%) and water use efficiency (kg/m3). Normal water supplies (24 cb) clearly led to high percentage losses in bulb dry weight compared to the other water stress treatments. The results indicated that the application of 75% NPK plus the bio-fertilizer Soft Guard significantly improved the average bulb weight (g/plant), bulb diameter (cm), bulb length (cm), total bulb yield (t/ha), marketable bulb yield (t/ha) and dry matter (%) compared with the other fertilization treatments.