Phenylacetic acid extraction from an aqueous system gets consideration because of its extensive uses in the production of β-lactam antibiotics. In the present paper, reactive extraction has been investigated for the removal of phenylacetic acid by tri-n-butyl phosphate from the aqueous phase in benzene, hexanol, and rice bran oil as diluents. Reactive extraction data were discussed in terms of overall distribution coefficients (D o ), loading ratio (ϕ), degree of extraction (η %), and equilibrium complexation constants (E αβ ). The mass action law model was used to represent equilibrium of reactive extraction of phenylacetic acid−tri-n-butyl phosphate. Also the results on water coextraction have been presented. A further extensive discussion on toxicity, back extraction, and regeneration was given. It is a first kind of study for the removal of phenylacetic acid from the aqueous phase by reactive extraction using tri-nbutyl phosphate in benzene, hexanol, and rice bran oil.
In
the present study, extraction equilibria experiments for water
+ L(+)-tartaric acid + extractant/diluents were carried out at T = 300 ± 1 K for concentrations of L(+)-tartaric acid
(0.1 to 1.0 mol·kg–1) and Aliquat 336 (0.22
to 0.88 mol·kg–1) in various diluents (n-heptane, kerosene, n-octanol). The equilibrium
results were discussed in terms of the overall equilibrium complexation
constant (K
E(1:1)), loading ratio (z), extraction efficiency (E%), distribution
coefficient (K
D), dimerization coefficient
(D), and partition coefficient (P). Kerosene + 0.88 (mol·kg–1) Aliquat 336
was found to be a favorable solvent with 50% extraction efficiency
for the reactive extraction of L(+)-tartaric acid, whereas, 32.14%
for n-heptane + 0.88 (mol·kg–1) Aliquat 336, and 22.22% for 1-octanol + 0.88 (mol·kg–1) Aliquat 336. 1:1 acid–amine complex was proposed for all
the diluents with no overloading, that is, z <
0.5. A higher chemical extraction was observed in nonpolar diluents: n-heptane and kerosene. Further, equilibrium results were
fitted with relative basicity and mass action law model and it was
found that the relative basicity model predicted the results better
than the mass action law for reactive extraction of L(+)-tartaric
acid.
An
equilibrium isotherm of benzylformic acid with phosphoric acid
tributyl ester in carbon tetrachloride, decanol, kerosene, toluene,
and xylene at 298 K has been studied. The equilibrium data are discussed
in terms of partition coefficient (P), dimerization
constant (D), overall equilibrium complexation constant
(E), and loading factor (ϕ). Moreover, the
distribution coefficient (K
D) and extraction
efficiency (η%) with phosphoric acid tributyl ester in CCl4 is 0.199 to 52.1 and 16.6 to 98.1; in decanol, 5.66 to 45.9
and 85 to 97.9; in kerosene, 0.03 to 73.2 and 2.9 to 98.7; in toluene,
0.381 to 70.3 and 27.6 to 98.6; and in xylene, 0.322 to 57.7 and 24.3
to 98.3, respectively. The extraction efficiency of benzylformic acid
was found to be more than 95 % with all these diluents. Loading factor
ϕ < 0.5 was observed and it indicates that only 1:1 benzylformic
acid–phosphoric acid tributyl ester complex in above said diluents
were formed. Furthermore, the values of overall equilibrium complexation
are determined with the relative basicity model using experimental
result.
Phenylacetic acid is widely used in the pharmaceutical industry for production of antibiotics. The recovery of phenylacetic acid from dilute aqueous waste with tri-n-butyl phosphate in methyl isobutyl ketone and petroleum ether has been attempted, and the results are presented in terms of distribution coefficient, extraction efficiency, apparent equilibrium constant, and loading ratio. The mechanism of reactive extraction was analyzed and the stoichiometric ratio of phenylacetic acid to tri-n-butyl phosphate in methyl isobutyl ketone and petroleum ether was found to be 1:0.5 and 1:1.2. Mass action law was used to represent the reactive extraction equilibrium for phenylacetic acid−tri-n-butyl phosphate−diluents which satisfied much in the present study. FTIR spectroscopy was studied for confirmation of the formation of a complex between acid and extractant. Further relative basicity approach has been extended to represent the experimental results. The model is best suited to experimental results.
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