Extractant effect on the retention of the stationary phase in a rotating coiled column

This is an open access article that be found at the links below - Copyright @ 2002 Springer VerlagThe effects of physicochemical properties of two-phase liquid systems (interfacial tension and differences in density and viscosity) on the retention of the stationary phase in the column were examined. These effects mainly determine the separation parameters of compounds. Extractant/decane–aqueous phase systems were used; their physicochemical properties changed both as a result of adding an extractant (di-(2-ethylhexyl) phosphoric acid, trioctylamine, or tributyl phosphate) to the organic solvent and because of a change in the composition of the aqueous phase. Aqueous ammonium sulfate of varying concentration was used as a mobile phase. It was shown that interfacial tension substantially affects the behavior of the systems under consideration. An increase in the ammonium sulfate concentration only slightly affects the retention factor of the stationary phase in the column. With a proper choice of the stationary phase, countercurrent chromatography can be used for the extraction of components from salt solutions of various concentrations

The efficiency of substance separation in countercurrent liquid chromatography

This is an open access article that can be found from the links below - Copyright @ 2003 Springer VerlagThe effect of hydrodynamic parameters and the specific features of instrument design on the efficiency of substance separation in countercurrent liquid chromatography (CCC) was studied using a constant retention factor of the stationary phase in the column. The study was conducted with the separation of benzyl alcohol and p-cresol in a two-phase liquid system heptane–ethyl acetate–methanol–water (1.4 : 0.6 : 1 : 1) in as an example. It was shown that the peak resolution is improved with an increase in the rotational speed of the column and a decrease in the flow rate of the mobile phase. The best peak separation was attained using columns for which the ratio of the column rotation radius to the radius of column revolution was 0.615. It was shown that countercurrent chromatography allows the separation of substances with low partition constants (K < 1)="" in="" dilute="" solutions.="" the="" volume="" of="" the="" test="" sample="" may="" be="" up="" to="" 15%="" of="" the="" total="" volume="" of="" the="" chromatography=""

Separation of substances in rotating coiled columns: From trace elements to microparticles

This is an open access article that can be found from the links below - Copyright @ Springer VerlagThe potentialities of rotating coiled columns in countercurrent chromatography (CCC) and centrifugal field-flow fractionation (CFFF) are demonstrated. A rotating coiled column is a fluoroplastic or steel coil wound around a rigid cylindrical drum, which revolves about its axis and, at the same time, revolves around the central axis of the device called planet centrifuge. The stationary (liquid, solid, or heterogeneous) phase is retained in the column because of the centrifugal force field, and the mobile liquid phase is continuously pumped through the column. The methods for recovery, separation, and preconcentration of various trace elements in geological samples and high-purity substances with the use of two-phase liquid systems (CCC) are developed. Procedures are proposed for the continuous sequential extraction of various element species from soil and for the recovery of polycyclic aromatic hydrocarbons from sewage sludge with the use of natural suspensions or solid particulates as stationary phases. It is also shown that rotating coiled columns can be used in a new field, microparticle fractionation by CFFF

Ultrafiltration assisted by water-soluble poly(diallyl dimethyl ammonium chloride) for As(V) removal

WOS: 000370352800016Arsenic is a very toxic element that must be removed efficiently from aqueous streams. Among the most promising techniques used for the removal of arsenic are separation methods using membranes. In this study, a regenerated cellulose ultrafiltration (UF) membrane and a poly(diallyl dimethyl ammonium chloride) P(DADMAC) were coupled and used in combination to remove As(V) from an aqueous solution. The influences of pH, the polymer: As(V) molar ratio, and the presence of interfering ions such as chloride and sulfate were investigated in arsenic removal via the washing method. The efficient retention of arsenic was observed at pH 7 with a 5: 1 polymer: As molar ratio and with an efficiency of approximately 85 % at Z = 10 for P(DADMAC). The maximum retention capacity of As(V) was determined by the enrichment method, and the results indicated that 194 mg of As(V) was removed per gram of polymer. Finally, using enrichment and washing methods sequentially, the sorption-desorption process and regeneration of P(DADMAC) were performed successfully.FONDECYTComision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)CONICYT FONDECYT [1110079, 11140324]; PIA [Anillo ACT-130]; REDOC (MINEDUC Project) at U. de Concepcion [UCO1202]; 7FP-MC Actions Grant, CHILTURPOL2 (PIRSES-GA Project) [269153]The authors thank the FONDECYT ( Project No. 1110079), PIA (Anillo ACT-130), REDOC (MINEDUC Project UCO1202 at U. de Concepcion). 7FP-MC Actions Grant, CHILTURPOL2 (PIRSES-GA-2009 Project, Grant No. 269153) and Marie Curie Program. Julio Sanchez thanks FONDECYT ( Grant No. 11140324) and CIPA, Chile