Jan Szymanowski

COMPOSITION OF CYANEX® 923, CYANEX® 925, CYANEX® 921 AND TOPO

ABSTRACT The composition of commercial reagents CYANEX® 923, CYANEX® 925, CYANEX® 921 and TOPO was investigated by GC/MS. CYANEX® 923 contains 18 components. 17 compounds were identified as trialkylphosphine oxides, mainly with normal (92.4) hexyl and octyl groups. CYANEX® 925 consists of 19 components. The reagent contains 65.9% kyphosphine oxides, mainly with isooctyl groups. The reagent contains also trialkylphosphine sulphides, dialkyldithiophosphinic acids and dialkyldisulphides having octyl and butyl groups. Trialkylphosphine sulphides and dialkyldithiophosphinic acids are present in amount of 26.8% be also considered as the active substance. CYANEX® 921 and TOPO are high quality reagents with the content of the active substance of about 99%. Trioctylphosphine oxide is the main component.

Analysis of Nonionic Surfactants with Polyoxyethylene Chains by High-Performance Liquid Chromatography

Abstract A critical review of HPLC methods for analysis of nonionic surfactants on normal and reversed phases, molecularx sieves and ion exchangers with UV, RI, FID, fluorometric, conductometric, MS and ELSD detection is presented.

MODELLING OF EXTRACTION EQUILIBRIUM FOR COPPER( II) EXTRACTION BY PYRIDINECARBOXYLIC ACID ESTERS FROM CONCENTRATED CHLORIDE SOLUTIONS AT CONSTANT WATER ACTIVITY AND CONSTANT TOTAL CONCENTRATION OF IONIC OR MOLECULAR SPECIES DISSOLVED IN THE AQUEOUS SOLUTION

Abstract The extraction of copper(D) from concentrated chloride ion solutions by various pyridinecarboxylic acid esters is investigated. It is shown that the efficiency of the extraction is strongly dependent on the water activity (aw) and total concentration (σ) of ionic or molecular species dissolved in the aqueous phase. For decyl nicotinate, decyl isonicotinate, decyl picolinate and ACORGA CLX-50 (all denoted EXT) in toluene, the distribution of copper(II) can be satisfactorily represented by the formation of CuCl2(EXT)2 in the organic phase on the condition of taking into account the existence of CuClx (2-X) complexes (x = 1 to 4) in the aqueous phase. The apparent extraction constant KeX and stability constants |βi of the variousCuOx (2-X) complexes are estimated for two aqueous media corresponding to aw andσ= 0.835 and a = 8.0 mol.L-1, and aw = 0.617 and σ = 12.0 mol.L-1, respectively. On the other hand, in the case of ACORGA CLX-50 in kerosene, more complex phenomena influencing the activity coeff...

KINETICS AND INTERFACIAL PHENOMENA

ABSTRACT Kinetics and interfacial phenomena in solvent extraction of metal ions are reviewed. The importance of interfacial reactions is discussed. The use of new modern techniques to study extraction is also presented.

Interfacial activity of model 2-hydroxy-5-alkylbenzophenone oximes and their intermediates

Abstract The interfacial tension at octane/water and toluene/water systems containing 2-hydroxy-5-alkylbenzophenone E and Z oximes, 2-hydroxy-5-alkylbenzophenones, 4-alkylphenols, and 4-alkylphenyl benzoates having different alkyls was determined and interpreted. At toluene/water and octane/water systems the interfacial tension increases as the alkyl length increases and decreases, respectively. Compounds having a branched alkyl exhibit lower surface activity. It was demonstrated that this opposit effect of the alkyl length can be explained by different strengths of the cohesion interactions in the organic phase, and their influence upon the compounds hydrophile lipophile balance. The depth of the hydrophilic group penetration into the aqueous layers seems to be a barrier retarding the rate of copper extraction.

The surface excess isotherms and the mechanism of copper extraction by hydroxyoximes

Abstract Different adsorption isotherms were used to determine the surface excess isotherms for model 4-alkylphenols and 2-hydroxy-5-alkylbenzophenones and their E and Z oximes in octane/water and toluene/water systems and used to discuss the kinetics and the interfacial mechanism of extracting copper from acidic sulfate solutions. The results obtained suggest that the reaction proceeds according to an interfacial mechanism with the formation of the stable 2:1 complex from the intermediate 1:1 complex and the oxime molecule near the interface as the slowest step.

Recovery of various phenols and phenylamines by micellar enhanced ultrafiltration and cloud point separation

The recovery of organic pollutants by micellar enhanced ultrafiltration and cloud point technique was studied. It was found that micellar enhanced ultrafiltration and cloud point technique enable high recovery of some organic pollutants without using any hydrocarbon solvents. The cloud point technique gives higher recovery than ultrafiltration. Appropriate surfactants having low critical micelle concentration and low cloud point must be used. Oxyethylated fatty acid methyl esters are the most appropriate for cloud point separation as, having ester groups, they are quickly hydrolyzed in sewage systems. CTAB and SDS are appropriate for ultrafiltration. The recovery of pollutants in both considered techniques can be estimated from the micelle binding constants or from linear solvation free energy relationships according to the Abraham model. The efficiency of separation increases with an increase of pollutant hydrophobicity and excess molar refraction. Hydrogen bond acidity of pollutants improves separation from systems containing nonionic surfactants and CTAB but it does not affect separation in the presence of SDS. Hydrogen bond basicity and dipolarity of pollutants decrease the recovery. The derived models enable the selection of pollutants which can be efficiently removed from aqueous streams by the cloud point technique and micellar enhanced ultrafiltration.

RECOVERY OF PHENOL WITH CYANEX® 923 IN MEMBRANE EXTRACTION-STRIPPING SYSTEMS

The recovery of phenol from aqueous solutions with CYANEX® 923 was studied. Classical dispersive extraction and three membrane extraction-stripping systems (bulk liquid membranes, three-phase hollow fiber contactor and two hollow fiber modules set-up) were used. It was found that CYANEX® 923 was a convenient carrier for recovery of phenol from aqueous streams in extraction-stripping membrane processes. The problem of emulsion formation, so important in dispersive extraction, was avoided. Both mass transfer experiments in different membrane systems and measurement of the dynamic interfacial tension demonstrated importance of the interfacial phenomena occurring in the stripping stage. A blocking of this interface was observed that resulted in a decrease of phenol mass transfer.

Increments of some polarity parameters for polyoxyethylene glycol dialkyl ethers and for some of their sulphur analogues

Abstract Gas-liquid chromatography was used to determine the polarity of pure model polyoxyethylene glycol dialkyl ethers and of some their sulphur analogues. The polarity parameters were correlated with the surfactant structure and increments for characteristic groups were determined. These values can be used to estimate the polarity of surfactants using only their formulae.

Micellar-enhanced ultrafiltration of phenol by means of oxyethylated fatty acid methyl esters

The optimized application of micellar-enhanced ultrafiltration (MEUF) in industrial scale requires the ability to develop simulation models. The more conventional approach for the description of relationships between operation conditions like, for example, surfactant concentration and separation performance and fouling, centers on the evaluation of overall resistance and time-independent relationships between concentrations before and after the membrane. In this paper, a novel approach is presented. It is based in the evaluation of relationships between averaged resistance and permeation fluxes, and a molar ratio pollutant/surfactant to predict the efficiency of the separation. The evolution of the additional resistance to permeation generated by the deposition of surfactant on the membrane is described as a sequence of: a maximum initial resistance due to gelification; a decrease in the resistance, apparently connected with the deformation of the surfactant gel by the permeating flux; and an aging effect. It is observed that different pollutants have different effects on the initial resistance and its evolution. In the case of phenol, higher concentration causes an increase of the initial resistance. It does not seem to have an effect on the aging rate.