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Dielectric relaxation of zeolites
React. Polym. 17 (1992) 115-139
135
system with a fluorescence detector. Styrene-divinylbenzene was the stationary phase and aqueous methanol mixed solvent containing tetrabutylammonium + and B40 2- as eluent was used. Under optimum conditions, the relationship between peak heights and the amounts of Sn(IV) was linear from 1.8 to 60 ng, the detection limit of Sn(IV) was 12 pg as S / N = 3 and the relative standard deviation for 10 determinations was 2.7% at a level of 5 ng of Sn(IV). Many metal cations, except Mg 2÷ and Ca 2+, did not interfere with the determination of Sn(IV). Tin in brass can be successfully determined.
New development in the ion chromatography of cations K.-H. Steeg and K. B~ichmann Technische Hochschule Darmstadt, Fachbereich Chemie, Hochschulstr. 10, G-6100 Darmstadt, Germany Without a complexing reagent in the mobile phase the divalent transition metals cannot be separated on a sulfonic cation-exchanger. Using a Ce(III) eluent (for sensitive indirect fluorescene detection) with a complexing reagent is not possible because the Ce(III) reacts with it. So we decided to develop a suitable complexing stationary phase. An endcapped ODS column (3/xm) (Waters) was coated with a complexing reagent. But nearly the same chromatograms, however, were obtained both with or without coating. This may probably be due to the residual silanol activity. The next we tried was a polymer column (Euro-Gel PRP, Knauer) but with similar results. A graphitised carbon column (Hypercarb, Shandon) was even worse. In this case the reason for the poor results might be the high II-electron density. A polymer-coated silica material (MH-1, Gynkotek) gave good results. We tested the inertness of the column by using water as the eluent and injection of Ce(III). This column allows the detection of as little as 30 n g / m i Ce(III) whereas the other columns did not achieve less than 12 ~g/ml. We coated this column with 2-hydroxydodecanoic acid and obtained good separations for Mn(II), Co(II), Ni(II) and Zn(II). The elution order was in increasing complex stabilities. Cations like Pb(II), Cu(II) or Th(IV) gave even stronger complexes than Ce(III) does and cannot be eluted from the column. The alkaline earth cations co-elute with Mn(II).
Theoretical investigation of thermal ion-exchange parametric pumping T. Szfinya
Department of Chemical Process Engineering, Veszpr~m University, P.O. Box 158, H-8201 Veszpr~m, Hungary Parametric pumping is a new, cyclic separation method for solutions that can advantageously be used in the separation of ionic components. In this process neither eluents nor reactants are needed, consequently the products are not diluted. Valuable, high purity compounds can be produced by the thermal ion-exchange parametric pumping process. The differential equation describing the batch, thermal ion-exchange parametric pumping process can be transformed to a quasi-linear differential equation is the case of equilibrium ion-exchange, neglecting mixing phenomena, electrolyte and solvent adsorption. The transformed equations can be solved by the help of the method of characteristics.
Dielectric relaxation of zeolites A. Szfisz and J. Liszi
Institute of Analytical Chemistry, University of Veszprdm, P.O. Box 158, H-820I Veszpr#m, Hungary Experiments were carried out over the range from 10 2 to 10 6 Hz with Linde A zeolites containing diverse cations (Na ÷, K ÷, Cs ÷, CH3NH~-, Ca 2÷ ). The water content of the samples was standardized. The dielectric properties of various zeolites were measured in paraffin oil suspensions.
136
React. Polym. 17 (1992) 115-139
The suspensions show two relaxation ranges. A method based on the use of reduced permittivity diagrams has been developed for the separation of the first and second relaxation domains. The characteristics of the second relaxation processes (Fouss-Kirkwood parameters, ~® and e0, Arrhenius energy of activation, the frequency of ionic jump as well as the dipole moments) indicate that the relaxation is nearly independent of the cation. The reorientation of water molecules as well as the Maxwell-Wagner effect seem to have a role in the dielectric relaxation of the investigated zeolites. Experimental proof is given that the results obtained by the suspension measuring technique and those by the compacted disc technique are in good agreement.
Trace analysis with vacancy ion chromatography Yoshinori Takata, Mitsuo Ito and Hitoshi Iwabuchi
Naka Works, Hitachi, Ltd., 882 Ichige, Katsuta, Ibaraki 312, Japan In vacancy chromatography, the sample is introduced onto the column in a continuous flow, while pure eluent is injected as a pulse. The application of vacancy chromatography to the determination of trace alkaline and alkaline earth metal ions in dilute aqueous solutions was studied. The area of the vacant peaks were proportional, not only to the concentrations of these analyte ions, but also to the concentration of injecting solution. Thus it is easy to increase the peak area by using highly concentrated solutions as the injecting solutions. The phenomenon of vacant peaks can be used for qualitative and quantitative analyses. The system which we studied is very useful for high sensitivity analysis of trace ions in relatively pure water.
The use of ammonium malonate in cation-exchange chromatography F. T a n o s
Research Institute for Telecommunication, P.O. Box 1025, Budapest, Hungary The cation-exchange behaviour of Fe, AI, Ga, In, Mn, Zn, Co, Ni, Mg, Ca, Y, Sc, La, Sm and Yb ions were studied with Dowex 50WX8 cation-exchange resin in ammonium malonate media at various pH. It was observed that the volume distribution coefficients increase with decreasing pH of the ammonium malonate and the useful range of pH is between 4 and 4.5 for the separation of Fe, A1, Ga, In, Cu and Sc ions from Ni, Co, Zn, Mn, Mg, Ca, Y, La, Sm and Yb ions. Separations are sharp and quantitative. The procedure can be used in the analysis of garnets and ferrites.
A new method of concentration and separation of metal species - back-extraction chromatography V.T. V ~ c a r i u a n d A. Pisoschi
I.C.P.M.R.R., M~burele, Str. Atomi~tilor No. 51, C.P. 5208, 76900 Bucure~ti, Romania This research work demonstrated the possibility of concentrating uranium and the separation from thorium and rare earths by chromatographic back-extraction. The best conditions for uranium extraction (from diluted solutions) with SME-529 solutions in kerosene have been established. The organic phase containing uranium was passed through columns filled with sulphonic cationites or strong base anionites pretreated with HC1 or H2SO 4. The best conditions have been found for the transfer of uranium from the organic phase into the ion-exchange resin phase by means of the aqueous film surrounding the resin pearls. In order to separate uranium from thorium and rare earths, we studied the extraction parameters of these with naphtenic acid solution., The organic phase which preselected by extraction the elements to be separated, was passed through columns filled with anionites or cationites previously treated with various acids. Using strong base resin Vionit AT-1 pretreated with HCI ( > 5 N) a separation of uranium above 1 0 3 w a s made.
135
system with a fluorescence detector. Styrene-divinylbenzene was the stationary phase and aqueous methanol mixed solvent containing tetrabutylammonium + and B40 2- as eluent was used. Under optimum conditions, the relationship between peak heights and the amounts of Sn(IV) was linear from 1.8 to 60 ng, the detection limit of Sn(IV) was 12 pg as S / N = 3 and the relative standard deviation for 10 determinations was 2.7% at a level of 5 ng of Sn(IV). Many metal cations, except Mg 2÷ and Ca 2+, did not interfere with the determination of Sn(IV). Tin in brass can be successfully determined.
New development in the ion chromatography of cations K.-H. Steeg and K. B~ichmann Technische Hochschule Darmstadt, Fachbereich Chemie, Hochschulstr. 10, G-6100 Darmstadt, Germany Without a complexing reagent in the mobile phase the divalent transition metals cannot be separated on a sulfonic cation-exchanger. Using a Ce(III) eluent (for sensitive indirect fluorescene detection) with a complexing reagent is not possible because the Ce(III) reacts with it. So we decided to develop a suitable complexing stationary phase. An endcapped ODS column (3/xm) (Waters) was coated with a complexing reagent. But nearly the same chromatograms, however, were obtained both with or without coating. This may probably be due to the residual silanol activity. The next we tried was a polymer column (Euro-Gel PRP, Knauer) but with similar results. A graphitised carbon column (Hypercarb, Shandon) was even worse. In this case the reason for the poor results might be the high II-electron density. A polymer-coated silica material (MH-1, Gynkotek) gave good results. We tested the inertness of the column by using water as the eluent and injection of Ce(III). This column allows the detection of as little as 30 n g / m i Ce(III) whereas the other columns did not achieve less than 12 ~g/ml. We coated this column with 2-hydroxydodecanoic acid and obtained good separations for Mn(II), Co(II), Ni(II) and Zn(II). The elution order was in increasing complex stabilities. Cations like Pb(II), Cu(II) or Th(IV) gave even stronger complexes than Ce(III) does and cannot be eluted from the column. The alkaline earth cations co-elute with Mn(II).
Theoretical investigation of thermal ion-exchange parametric pumping T. Szfinya
Department of Chemical Process Engineering, Veszpr~m University, P.O. Box 158, H-8201 Veszpr~m, Hungary Parametric pumping is a new, cyclic separation method for solutions that can advantageously be used in the separation of ionic components. In this process neither eluents nor reactants are needed, consequently the products are not diluted. Valuable, high purity compounds can be produced by the thermal ion-exchange parametric pumping process. The differential equation describing the batch, thermal ion-exchange parametric pumping process can be transformed to a quasi-linear differential equation is the case of equilibrium ion-exchange, neglecting mixing phenomena, electrolyte and solvent adsorption. The transformed equations can be solved by the help of the method of characteristics.
Dielectric relaxation of zeolites A. Szfisz and J. Liszi
Institute of Analytical Chemistry, University of Veszprdm, P.O. Box 158, H-820I Veszpr#m, Hungary Experiments were carried out over the range from 10 2 to 10 6 Hz with Linde A zeolites containing diverse cations (Na ÷, K ÷, Cs ÷, CH3NH~-, Ca 2÷ ). The water content of the samples was standardized. The dielectric properties of various zeolites were measured in paraffin oil suspensions.
136
React. Polym. 17 (1992) 115-139
The suspensions show two relaxation ranges. A method based on the use of reduced permittivity diagrams has been developed for the separation of the first and second relaxation domains. The characteristics of the second relaxation processes (Fouss-Kirkwood parameters, ~® and e0, Arrhenius energy of activation, the frequency of ionic jump as well as the dipole moments) indicate that the relaxation is nearly independent of the cation. The reorientation of water molecules as well as the Maxwell-Wagner effect seem to have a role in the dielectric relaxation of the investigated zeolites. Experimental proof is given that the results obtained by the suspension measuring technique and those by the compacted disc technique are in good agreement.
Trace analysis with vacancy ion chromatography Yoshinori Takata, Mitsuo Ito and Hitoshi Iwabuchi
Naka Works, Hitachi, Ltd., 882 Ichige, Katsuta, Ibaraki 312, Japan In vacancy chromatography, the sample is introduced onto the column in a continuous flow, while pure eluent is injected as a pulse. The application of vacancy chromatography to the determination of trace alkaline and alkaline earth metal ions in dilute aqueous solutions was studied. The area of the vacant peaks were proportional, not only to the concentrations of these analyte ions, but also to the concentration of injecting solution. Thus it is easy to increase the peak area by using highly concentrated solutions as the injecting solutions. The phenomenon of vacant peaks can be used for qualitative and quantitative analyses. The system which we studied is very useful for high sensitivity analysis of trace ions in relatively pure water.
The use of ammonium malonate in cation-exchange chromatography F. T a n o s
Research Institute for Telecommunication, P.O. Box 1025, Budapest, Hungary The cation-exchange behaviour of Fe, AI, Ga, In, Mn, Zn, Co, Ni, Mg, Ca, Y, Sc, La, Sm and Yb ions were studied with Dowex 50WX8 cation-exchange resin in ammonium malonate media at various pH. It was observed that the volume distribution coefficients increase with decreasing pH of the ammonium malonate and the useful range of pH is between 4 and 4.5 for the separation of Fe, A1, Ga, In, Cu and Sc ions from Ni, Co, Zn, Mn, Mg, Ca, Y, La, Sm and Yb ions. Separations are sharp and quantitative. The procedure can be used in the analysis of garnets and ferrites.
A new method of concentration and separation of metal species - back-extraction chromatography V.T. V ~ c a r i u a n d A. Pisoschi
I.C.P.M.R.R., M~burele, Str. Atomi~tilor No. 51, C.P. 5208, 76900 Bucure~ti, Romania This research work demonstrated the possibility of concentrating uranium and the separation from thorium and rare earths by chromatographic back-extraction. The best conditions for uranium extraction (from diluted solutions) with SME-529 solutions in kerosene have been established. The organic phase containing uranium was passed through columns filled with sulphonic cationites or strong base anionites pretreated with HC1 or H2SO 4. The best conditions have been found for the transfer of uranium from the organic phase into the ion-exchange resin phase by means of the aqueous film surrounding the resin pearls. In order to separate uranium from thorium and rare earths, we studied the extraction parameters of these with naphtenic acid solution., The organic phase which preselected by extraction the elements to be separated, was passed through columns filled with anionites or cationites previously treated with various acids. Using strong base resin Vionit AT-1 pretreated with HCI ( > 5 N) a separation of uranium above 1 0 3 w a s made.