Interfacial activity and rate of palladium(II) extraction with decyl pyridine monocarboxylates

Decyl isonicotiniate and decyl nicotiniate permit a rapid extraction of palladium(II) from its hydrochloride solutions. Decyl picoliniate is not a suitable extractant. 4-Octylphenylamine can act as a phase transfer catalyst when its concentration in the organic phase is at least 2·5 × 10^?4 M . It seems that the interfacial adsorption of pyridine carboxylates and of 4-octylphenylamine is not the decisive phenomenon in palladium(II) extraction. The negligible protonation of the pyridine-type extractants and the phase transfer catalysis explains well the quick extraction of palladium(II) with the commercial and highly hydrophobic extractant ACORGA CLX-50.     

High ethoxylated alcohols with narrow distribution of homologues

Homologue distributions of alcohol ethoxylates obtained with an unconventional calcium-based catalyst and NaOH as the conventional catalyst are studied in the range of average polyaddition degree from 8 to 15. The fractional compositions of those high molecular weight derivatives of dodecanol and other technical alcohols, Lial 125 and Radianol 1724, are determined as peak area percentages from HPLC chromatograms. Some physico-chemical characteristics of the products as well as by-product contents are also presented. It is shown that the differences in fractional contents between the broad and narrow homologue distributed equivalents remain very significant in that range of higher ethoxylation grades. Consequently, the influence of homologue distributions on some properties of the products can be expected in their practical applications.     

Identification and In Silico Characterization of a Novel COLGALT2 Gene Variant in a Child with Mucosal Rectal Prolapse

Rectal prolapse is influenced by many factors including connective tissue dysfunction. Currently, there is no data about genetic contribution in the etiology of this disorder. In this study, we performed trio whole-exome sequencing in an 11-year-old girl with mucosal rectal prolapse and her parents and sibling. Genetic testing revealed a novel heterozygous missense variant c.1406G>T; p.G469V in exon 11 of the COLGALT2 gene encoding the GLT25 D2 enzyme. Sanger sequencing confirmed this variant only in the patient while the mother, father and sister showed a wild-type sequence. The pathogenicity of the novel variant was predicted using 10 different in silico tools that classified it as pathogenic. Further, in silico prediction, according to Phyre2, Project HOPE, I-Mutant3.0 and MutPred2 showed that the missense variant can decrease protein stability and cause alterations in the physical properties of amino acids resulting in structural and functional changes of the GLT25D2 protein. In conclusion, the present study identifies a previously unknown missense mutation in the COLGALT2 gene that encodes the enzyme involved in collagen glycosylation. The clinical features observed in the patient and the results of in silico analysis suggest that the new genetic variant can be pathogenic.     

Synthesis and surface activity of nonionic surfactants containing fluorocarbon hydrophobes

Nonionic surfactants having polydisperse polyoxyethylene chains and highly fluorinated hydrophobes were synthesized via a complex reaction route and their adsorption at water/air interfaces studied. They exhibit high surface activity and decrease both effectively and efficiently the surface tension of their aqueous solutions. The effect of the length of the polyoxyethylene chain upon surfactant surface activity is relatively low. Lower values of surface tension, below 30 mN m^?1, are obtained for surfactants having a low degree of ethoxylation. Surfactants having two terminal highly fluorinated hydrophobes are less surface active than analogues with one terminal hydrophobe.     

KINETICS AND INTERFACIAL PHENOMENA IN CLASSICAL AND MICELLAR EXTRACTION SYSTEMS

ABSTRACT

Kinetic and interfacial phenomena in classical extraction systems and in micellar media are discussed. The work is limited to the process controlled by the kinetics. Phenomena affecting the rate of extraction are examined and appropriate examples of acceleration or inhibition of metal extraction with hydrophobic chelating extractants are given. The effects of surfactants on the rate of extraction and complexation in micellar media are reviewed. The effect of extractant hydrophobicity upon their interfacial behaviour and the rate of extraction in classical and non classical extraction systems is considered. Appropriate kinetic models for interfacial and bulk volume reactions are presented. They suggest that the true mechanism of classical and non classical solvent extraction may include both of these pathways. Although important differences exist between classical extraction systems and micellar systems their kinetic behaviour indicates serious similarities. It seems that further studies of the micellar systems with the use of a broad range of extractants may deliver useful information to predict the structural effects of chelates upon the kinetics of metal extraction.     

On negative dispersion without absorption in bichromatically driven two-level systems

Abstract

The possibility of obtaining strong negative dispersion without absorption in the central resonance structure of the spectrum of a bichromatically driven two-level system is investigated. A nonlinear analysis is performed using the technique of continued fractions with respect to the dressedstate basis of a strong pumping laser. We discuss the transition between the two regimes of the monochromatic driving case with a weak probing laser and of nearly equally strong lasers in terms of the contributions from coherences and populations of these dressed states. In contrast with the strong dependence of the Rabi side bands on probe field intensity, we find a remarkable stability of the negative dispersion in the central resonance structure.     

Interfacial activity of narrow-range alcohol oxyethylates

Surface and interfacial tension isotherms for narrow-range distribution ALFOL 1214 alcohol oxyethylates were determined and compared with those obtained for broad-range alcohol oxyethylates. Various adsorption parameters were estimated. The effectiveness of surface tension reduction decreases when the length of polyoxyethylene hydrophile increases. Micellization is observed at log cmc ranging from −4.7 to −3.3. Effects of the length and distribution of the polyoxyethylene chain on cmc are very small. A minimum of A _min/N _av ^0.5 is obtained for N _av=8, where A _min and N _av denote the minimum interfacial area occupied by a statistical molecule at the saturated interface and the average degree of oxyethylation, respectively. The interface becomes saturated at pC ₂₀=−5.61±0.35, where pC ₂₀ denotes the logarithm of concentration required to obtain the surface pressure equal to 20 mNm⁻¹. The highest and lowest values of the surface excess at saturation and the free energy of adsorption, respectively, are obtained for an average degree of oxyethylation equal to 8. Parameters are correlated with the average degree of oxyethylation and the oxyethylene chain distribution parameter according to empirical second-order polynomials. Small differences in adsorption abilities at the water/air interface are only observed for narrow- and broad-range distributed oxyethylates. The differences become important for adsorption at the hexadecane/water interface. The lowest values of interfacial tension are obtained for narrow-range oxyethylates with N _av=7 and 8. The Krefeld fabric detergency tests indicated that the best detergency was observed for alcohol oxyethylates with N _av=5–7. Narrow-range oxyethylates exhibit somewhat better washing abilities than the broad-range products. No relationship between detergency of alcohol oxyethylates and their abilities to adsorb at the water/air and water/hydrocarbon interfaces is observed.     

KINETICS MODEL FOR INTERFACIAL REACTION OF COPPER EXTRACTION WITH 1-(2'-HYDROXY-5'-NONYLPHENYL)-l-ETHANONE (E)-OXIME AND 1-(2'-HYDROXY-5'-METHYLPHENYL)-1-DECANONE (E)-OXIME

Abstract

A kinetic model for the interfacial reaction of copper extraction with Individual 1-(2'-hydroxy-5'-nonylphenyl)-1-ethanone (E)-oxime and 1-(2'-hydroxy-5'-methylphenyl)-1-decanone (E)-oxime having the same hydrophobicity was used to interpret the effect of hydroxyoxime partition and interfacial activity upon the rate of copper extraction from acidic sulfate solutions. Due to similar hydrophobicity of studied extractants the proposed model, which is very sensitive to the errors of the partition coefficient determination, cannot support any version of extraction mechanism.     

INTERFACIAL TENSION ESTIMATION IN ORGANIC/AQUEOUS SYSTEM

ABSTRACT

Linear solvation energy relationships are used to estimate the interfacial tension at solvent/water interfaces for systems containing ‘dry’ and ‘wet’ solvents. The correlation analysis works also in the systems containing Primene 81R and metal salts. The models

?^° = a - b, log x_S,W - b₂ log x_W,S and

?^° = a - b log (x_S,W + x_W,S)give good estimation of the interfacial tension. In the systems containing Primene 81R the surface pressure is correlated with solvent parameters according to relation ?°-7 = a + D7r*=c/3     

Interfacial activity of 4-alkylphenylamines and the rate of palladium(II) extraction

Interfacial tension isotherms were determined in hydrocarbon-water systems for 4-alkylphenylamines containing from 6 to 16 carbon atoms in their alkyl chains, and the surface excess isotherms were computed and interpreted using various adsorption isotherms. Palladium(II) was extracted with 4-alkylphenylamines from 3 M HCI solutions. The maximum extraction rate of palladium(II) is observed for 4-decyl- and 4-dodecylphenylamines which exhibit good interfacial activity. Compounds soluble in the aqueous phase (4-hexylphenylamine) or in toluene (4-hexadecylphenylamine) extract palladium(II) slower than 4-decyl- and 4-dodecyl- phenylamines.