Aynur Senol

Amine extraction of chromium(VI) from aqueous acidic solutions

Abstract Extraction of chromium (Cr(VI)) from the aqueous acidic solution into a co-existing organic phase containing Alamine 336 (C 8 C 10 tertiary amine mixture) and diluent (xylene) was studied at isothermal condition (298.2 K). The distribution ratio was measured for two initial aqueous concentrations of Cr(VI), i.e. 0.019 mol/dm 3 (1 mg/ml) and 0.192 mol/dm 3 (10 mg/ml) against various molarities of the aqueous phase sulphuric acid in the range from 0.05 to 4 mol/dm 3 . The overall loading factor of amine ( Z t ) exhibits a maximum restricted between the aqueous phase acidity of 0.75–1 mol/dm 3 H 2 SO 4 for a lower amine concentration related to the ratio of initial concentrations of amine to Cr(VI), C NH 3 ° /C Cr(VI) °≈0.75 or less than this limit. In the range above this value a continual decreasing of Z t has been observed. A comparative study of the extraction degrees of Cr(VI) by Alamine 336 and Aliquat 336 extractants for the pH range of 1–7 has been evaluated. The results were correlated using various versions of the mass action law, i.e. a chemodel approach and a modified version of the Langmuir equilibrium model comprising the formation of only one type Cr(VI)–amine aggregated structure.

Extraction equilibria of formic and levulinic acids using Alamine 308/diluent and conventional solvent systems

Abstract Distribution of formic and levulinic acids between water and Alamine 308 (triisooctylamine) dissolved in C 6 -ring included diluents of proton-donating and -accepting (cyclohexanone, methylcyclohexanol), polar (1,2-dichlorobenzene, 1,2-DCB) and inert (toluene) types, as well as a comparison with the extraction equilibria of pure diluent alone (1-hexanol) have been studied at 298 K. From tested C 6 ring-containing diluents, cyclic alcohol/amine system yields the highest synergistic extraction efficiency. The strength of the complex solvation was found to be reasonably large for halogenated aromatics favouring mainly the formation of acid 1 –amine 1 structure. The influence of the acid structure over distribution has been evaluated through comparing the extractabilities of four acids containing different functional groups, i.e. formic, levulinic, nicotinic and valeric acids. The results were correlated using a modified linear solvation energy relation (METLER) and versions of the mass action law, i.e. a chemodel approach and a modified Langmuir equilibrium model comprising the formation of one or two acid–amine complex formation.

Extraction equilibria of valeric acid using (Alamine 336/diluent) and conventional solvent systems. Modeling considerations

Abstract Distribution of valeric acid between water and Alamine 336, a mixture of tertiary aliphatic amines dissolved in various (proton-donating and -accepting, polar and nonpolar) diluents, as well as a comparison with the extraction equilibria of pure diluent alone, have been studied at 298 K. The influence of the acid structure over distribution has been interpreted through comparing the extractabilities of four acids containing different functional groups, i.e. valeric, formic, levulinic and nicotinic acids. The results were correlated using a modified linear solvation energy relation (METLER) and various versions of the mass action law, i.e. a chemodel approach and a modified Langmuir equilibrium model comprising the formation of one or two acids per multiple amines aggregated structures. The reliability of the proposed extraction models has been analyzed statistically on the basis of the overall loading factor of amine, Z t , using a log-ratio objective function.

Predicting Liquid–Liquid Equilibria of Amine Extraction of Carboxylic Acid Through Solvation Energy Relation

Abstract Long‐chain, aliphatic tertiary amines (e.g., Alamine 336 or 308) dissolved in suitable organic solvents are known to be effective extractants for carboxylic acids. A log‐basis approach SERAS (solvation energy relation for amine systems) has been proposed to estimate the properties and liquid–liquid equilibria (LLE) of amine/diluent/organic acid associated systems containing protic and nonprotic components. The model combines the solvatochromic parameters of solvation energy of solution with the thermodynamic factors derived from a group‐contribution method, i.e., UNIFAC‐Dortmund activity‐coefficient model. The reliability of the model has been analyzed against the LLE data for distribution of pyruvic (2‐oxopropanoic) acid between water and Alamine 308 (triisooctylamine) dissolved in C6‐ring‐included diluents of proton‐donating and ‐accepting (cyclohexanone, methylcyclohexanol), polar (1,2‐dichlorobenzene), and inert (toluene) types. The proposed solvatochromic approach SERAS is expected to be an improvement in data fit clarifying the simultaneous impact of hydrogen bonding, solubility, and thermodynamic factors of components on LLE. The model matches the experimental data, yielding a mean relative error of ±13.9%. The results were also correlated using a version of the mass‐action law, i.e., a chemodel approach comprising the formation of one or two acid–amine complexes.

Mass transfer efficiency of randomly-packed column : modeling considerations

Abstract This article deals with the performance of a randomly packed distillation column depending on the effective vapor–liquid interfacial area ( a e ) and the flood ratio (% Fl ). An approach to design with respect to the derivatives of the function a e = f (% Fl ) has been evaluated using % Fl due to the Eckert flooding model. The proposed log–basis equation for a e of random packings is expected to be an improvement in data fit clarifying the simultaneous impact of loading, packing geometry and system properties on the performance of a moderate scale packed column. Capacity and efficiency data obtained on three sizes of a Raschig-type ceramic ring have been used to establish the basis for the model reliability analysis. Details underlying some aspects of selection of an appropriate algorithm for fitting the data are discussed.

Liquid–Liquid Extraction of Isovaleric Acid Using Alamine 308/Diluent and Conventional Solvent Systems: Effect of Diluent and Acid Structure

Abstract Distribution of isovaleric (3‐methyl butanoic) acid between water and Alamine 308 (triisooctylamine) dissolved in C5 and C6‐ring included diluents of proton‐donating and ‐accepting (cyclopentanol, cyclohexanone), polar (chlorobenzene) and inert (toluene) types, as well as a comparison with the extraction equilibria of pure diluent alone (chloroform) have been studied at 298 K. Among the tested C6 ring‐containing and aliphatic diluents, cyclic alcohol/amine system yields the highest synergistic extraction efficiency. The strength of the complex solvation was found to be reasonably large for halogenated aromatics favoring mainly the formation of acid1‐amine2 structure. The influence of the acid structure over distribution has been interpreted through comparing the extractabilities of seven acids containing different functional groups, i.e., isovaleric, formic, levulinic, acetic, propanoic, pyruvic and nicotinic acids. The results were correlated using a modified linear solvation energy relation (METLER) and versions of the mass action law, i.e., a chemodel approach and a modified Langmuir equilibrium model comprising the formation of one or two acid‐multiple amines complex formation.

PHASE EQUILIBRIUM FOR TERNARY LIQUID SYSTEMS OF WATER + CARBOXYLIC ACID + CHLORINATED HYDROCARBON: THERMODYNAMIC MODELING THROUGH SERLAS

ABSTRACT Liquid-liquid equilibrium data of the solubility (binodal) curves and tie-line end compositions are presented for mixtures of [water (1) + formic acid, or acetic acid, or propanoic acid (2) + chlorobenzene, or 1,2-dichloroethane (3)] at T = 293.2 K and P = 101.3 ± 0.7 kPa. A log-basis approach, SERLAS (solvation energy relation for liquid-associated system), has been proposed to estimate the properties and liquid-liquid equilibrium (LLE) of associated systems containing proton-donating and -accepting and polar components capable of a physical interaction through hydrogen bonding or dipole-dipole interaction. The tie lines were also correlated using the UNIFAC-original model. The reliability of the models has been analyzed against the LLE data with respect to the distribution coefficient and separation factor. The proposed model appears to be an improvement in data fit for the ternary systems, yielding a mean relative error of 10.1% for all the systems considered.

Optimal Reactive Extraction of Valeric Acid from Aqueous Solutions Using Tri-n-propyl amine/Diluent and Dibenzyl amine/Diluent Systems

Reactive extraction of valeric acid from water by tri-n-propyl amine (TPA) and dibenzyl amine (DBA) dissolved in polar oxygenated aliphatic diluents (diethyl sebacate, diethyl succinate, diethyl malonate, ethyl caprylate, ethyl valerate and isoamyl alcohol) has been studied at 298 0.2 K T = ± and P 101.3 0.7 kPa p = ± . Distribution data have been subjected to formulation of an optimization structure for effective acid separation. The optimization approach uses separation ratio R and synergistic enhancement SE factors to efficiently identify optimum extraction ranges. Among the examined alipha tic ester and alcohol diluents, monoesters exhibit higher solvation efficiency comprising acid1–amine1 complex formation, while isoamyl alcohol yields larger loading factors. The uptake capacity of the amine/diluent system is ranging in the order TPA > DBA. Modeling efforts based on the mass-action law principles have shown considerable success. The mass action law chemodel and modified Langmuir approach are quite accurate yielding mean errors of 0.9 % and 0.7 %, respectively.

Optimal Synergistic Extraction of Cr(VI) from Aqueous Acidic Media Using Alamine 300/Aliquat 336 and Di-n-octyl Amine/Tributyl Phosphate Mixed Reagents

Data for the extraction of chromium(VI) from aqueous sulfate solutions by Alamine 300/Aliquat 336 and di–n–octyl amine/tributyl phosphate (DOA/TBP) have been subjected to formulation of an optimization structure for an effective Cr(VI) separation based on the derivative variation method. Both experimentally and analytically defined optimum Cr(VI) removal efficiencies are ranging about 83–99%, 71–93%, and 60–73% for Alamine 300/Aliquat 336, DOA/TBP, and DOA, respectively. Modeling efforts based on mass-action law methodology and non-homogeneous differential approach have shown considerable success yielding a 10% mean error, and satisfies established limiting behavior of the physical event.