The influence of distribution coefficients on the separation factor of lithium isotopes was studied with Dowex 50W-X8, 200–400
mesh, ammonium form, strongly acidic cation exchanger by changing the pH and EDTA concentration of the eluent. It was found
that the larger the EDTA concentration in the buffer solution, the smaller the distribution coefficients were. The separation
factor was increased with decreasing EDTA concentration. The separation factor of lithium isotopes linearly increased up to
a distribution coefficient value of 30, and gradually increased above 30. The optimum value of distribution coefficient of
lithium to separate litihium isotopes was about 30. The distribution coefficient was increased with increasing pH, but the
separation factor of lithium isotopes has no relation with pH.6Li concentrated on the resin phase, and7Li in the solution phase.
Separation of magnesium isotopes was investigated by chemical ion exchange with synthesyzed 1,12-diaza-3,4:9,10-dibenzo-5,8-dioxacyclo pentadecane(NTOE) bonded merrifield peptide resin using elution chromatographic technique. The capacity of novel diazacrown ion exchanger was 0.29 meq/g dry resin. The heavier isotopes of magnesium were concentrated in the solution phase, while the lighter isotopes were enriched in the resin phase. The glass ion exchange column used in our experiment was 32 cm long with inner diameter of 0.2 cm, and 0.5M NH4Cl solution was used as an eluent. The single stage separation factor was determined according to the method of GLUECKAUF from the elution curve and isotopic assays. The separation factors of 24Mg2+–25Mg2+, 24Mg2+–26Mg2+, and 25Mg2+–26Mg2+ were 1.063, 1.080, and 1.021, respectively.
Lithium and magnesium isotopes were separated by chemical ion exchange using hydrous manganese(IV) oxide and elution chromatography. The capacity of manganese(IV) oxide was 0.5 meq/g. The glass ion exchange column used was 35 cm long with an inner diameter of 0.2 cm, and 2.0M CH3COONH4 solution served as eluent. The single stage separation factor was determined from the elution curves and isotopic assays according to the method of Glueckauf. The separation factor of 6Li+-7Li+ was 1.022±0.002, those of 24Mg2+-25Mg2+, 24Mg2+-26Mg2+, and 25Mg2+-26Mg2+ were 1.012±0.001, 1.021±0.002, and 1.011±0.001, respectively.
Magnesium isotope separation was investigated by chemical ion exchange with the 1-aza-12-crown-4 (I) and the 1-aza-18-crown-6 (II) bonded Merrifield peptide resin using an elution chromatographic technique. The capacities of each novel monoazacrown ion exchanger were 1.0 meq/g for (I) and 2.3 meq/g for (II) bonded Merrifield peptide resins, respectively. The single stage separation factor was determined according to the method of Glueckauf from the elution curves and isotopic assays. The separation factors of magnesium isotope pairs, 24Mg2+–25Mg2+, 24Mg2+–26Mg2+ and 25Mg2+–26Mg2+ were 1.015, 1.029, and 1.014 for (I) and 1.012, 1.024, and 1.009 for (II) bonded Merrifield peptide resins, respectively.
A study on the elution chromatographic separation of lithium isotopes was carried out with a triazacrown trimerrifield peptide resin. The capacity of the triazacrown trimerrifield peptide resin has a value of 0.08 meq/g. Upon column chromatography [0.2 cm (I.D)×35 cm (height)] using 4.0M NH4Cl solution as an eluent, the single stage separation factor of 1.028 was obtained by the Glueckauf theory. The heavier isotope, 7Li, was concentrated in the resin phase, while the lighter isotope, 6Li, was enriched in the solution phase.
The influence of co-ions in the eluent on the separation factor () of lithium isotope separation has been studied by ion exchange chromatography. A strongly acid cation exchange resin (Dowex 50W-X8) was used for the separation of lithium isotopes. The co-ions used in eluent were H+, K+, Ba2+, Cu2+, Al3+ and Cr3+ as their chlorides. From the experiments, it was found that6Li was enriched in the resin phase and7Li in solution phase. At the same distribution coefficient (Kd=30), the separation factor increased linearly with the charge of co-ion (=1.0022 to 1.0039).
The influence of chelating agents on the separation factor, , of lithium isotopes separation was studied by ion exchange elution chromatography. Eluents contained the chelating agent having different number of coordination sites. The chelating agents used in eluent were Na-glycine (Na–Gly), 2Na-iminodiacetic acid (2Na-IDA), 3Na-nitrilotriacetic acid (3Na-NTA), and 4Na-ethylenediaminetetraacetic acid (4Na-EDTA). The ion exchanger was Dowex 50W-X8, sulfonic acid type, sodium form. As a result,6Li was enriched in resin phase, and7Li was in solution phase. The separation factor, , was gradually increased with increasing number of coordination site (=1.0022–1.0038) at the same distribution coefficient and with increasing distribution coefficients (=1.0017–1.0026) at the same concentration of chelating agents.
The purpose of this study was to conduct a thermal analysis of the hydrolysis and degradation behavior of biodegradable polymers
and bio-composites at 50°C and 90% relative humidity (RH). With increasing hydrolysis time, the thermal stability and degradation
temperature of polybutylene succinate (PBS) slightly decreased. The glass transition temperature (Tg) and melting temperature (Tm) of PBS and the anti-hydrolysis agent treated PBS did not vary significantly with increasing hydrolysis time, whereas those
of the trimethylolpropane triacrylate (TMPTA)-treated PBS slightly increased. With increasing hydrolysis time, the storage
modulus (E’) values of the bio-composites decreased, whereas those of the TMPTA treated bio-composites slightly increased. Also, the
tan values of the anti-hydrolysis agent and TMPTA treated PBS-BF bio-composites were slightly lower than those of the non-treated
bio-composites, due to the reduction in their degree of hydrolysis. The tanδmax peak temperature (Tg) of the anti-hydrolysis agent treated bio-composites was not significantly changed, whereas that of the TMPTA treated bio-composites
Authors:D. Kim, C. Kim, J. Jeon, J. Kim, and N. Lee
The novel N4S2 azacrown ion exchange resin was prepared. The ion exchange capacity of N4S2 ion exchanger was 0.34 meq/g dry resin. A study on the separation of lithium isotopes was carried out with N4S2 azacrown ion exchange resin. The lighter isotope,6Li is concentrated in the resin phase, while the heavier isotope,7Li is enriched in the solution phase. With column chromatography [0.1 cm (I.D.)×32 cm (height)] using 2.0M NH4Cl as an eluent, separation factor, a=1.034 was obtained.