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751.
Characterization of surface-confined ionic liquid stationary phases: impact of cation and anion identity on retention 总被引:1,自引:0,他引:1
Van Meter DS Oliver NJ Carle AB Dehm S Ridgway TH Stalcup AM 《Analytical and bioanalytical chemistry》2009,393(1):283-294
A series of surface-confined ionic liquid (SCIL) stationary phases for high-performance liquid chromatography were synthesized
in-house. The synthesized phases were characterized by the linear solvation energy relationship (LSER) method to determine
the effect of residual linking ligands and the role of the cation and the anion on retention. Statistical analysis was utilized
to determine whether the system coefficients returned from multiple linear regression analysis of chromatographic retention
data for a set of 28 neutral aromatic probe solutes were significantly different. Examination of the energetics of retention
via κ−κ plots agrees with the results obtained from the LSER analysis. Residual linking ligands were determined to contribute reversed-phase-type
retention character to the chromatographic system. Furthermore, retention on the SCIL phases was observed to be more profoundly
affected by the identity of the anion than by that of the cation. 相似文献
752.
This paper presents an extension of a previous investigation in which the behavior of nonpolar compounds in temperature-programmed
gas chromatographic runs was predicted using thermodynamic (entropy and enthalpy) parameters derived from isothermal runs.
In a similar manner, entropy and enthalpy parameters were determined for a Grob standard mixture of compounds with widely
varying chemical characteristics. These parameters were used to predict the retention times and chromatographic behaviors
of the compounds on four gas chromatography capillary columns: three that had phenyl-based stationary phases (with degrees
of substitution of 0%, 5% and 50%) and one with (50%) cyanopropyl substitution. The predictions matched data empirically obtained
from temperature-programmed chromatographic runs for all of the compounds extremely well, despite the wide variations in polarity
of both the compounds and stationary phases. Thus, the results indicate that such simulations could greatly reduce the time
and material costs of chromatographic optimizations. 相似文献
753.
Toyohide Takeuchi Budhi Oktavia Lee Wah Lim 《Analytical and bioanalytical chemistry》2009,393(4):1267-1272
Methyl-capped poly(ethylene oxide) moieties were chemically bonded to silica gel using an amine-reactive modification reagent
and evaluated as the stationary phase for ion chromatography. In this work, primary amino groups of an aminopropylsilica packing
material were reacted with methyl-PEO12-NHS ester (succinimidyl-{[N-methyl]-dodecaethyleneglycol} ester) in phosphate buffer (pH 7.0) at room temperature. The prepared poly(ethylene oxide)-bonded
stationary was evaluated for the separation of inorganic anions, and the retention behavior of inorganic anions on the prepared
stationary phase was examined. The elution order of the investigated anions was the same as that observed in common ion chromatography.
Both cations and anions of the eluent affected the retention of the analyte anions. Ion exchange was involved for the retention
of analyte anions, although the present stationary phase does not possess any discrete ion-exchange sites. The stationary
phase was applied to the separation of trace anions contained in tap water and a rock salt. 相似文献
754.
《Particuology》2023
Selenium pollution by coal utilization is of increasing concern. Calcium-iron (Ca–Fe) oxygen carriers (OCs) and alkali metal ions have strong inhibitory effects on selenium, which can reduce the emissions of selenium vapor. The retention mechanisms of selenium by Fe2O3, CaFe2O4, Ca2Fe2O5 and bottom ash are investigated during chemical looping gasification (CLG). Iron-based OC can oxidize H2Se(g) to SeO2(g); furthermore, lattice oxygen is released by Fe2O3, contributing to the formation of an Fe–O–Se structure to retain selenium and form selenite. Because calcium ferrite is poorly oxidizing, it cannot oxidize H2Se(g), but the CaO produced when OCs are reduced can react with H2Se(g) to form CaSe(s), and this process can be promoted by H2S(g). The best retention rates reached 32.301% when Ca2Fe2O5 was used. In the cyclic experiment, the selenium retention of the bottom ash gradually increases. Alkali metal ions in bottom ash are the main factor in retaining selenium. Ca2+ and Mg2+ do not easily vaporize due to their high melting points; therefore, their selenium retention is significantly better than that of K+ and Na+. This research provided a new idea for the removal of selenium by using OCs and bottom ash particles during CLG. 相似文献
755.
Dai Wang Hui Xie Qiang Liu Kexin Mu Zhennuo Song Weijian Xu Dr. Lei Tian Prof. Caizhen Zhu Prof. Jian Xu 《Angewandte Chemie (International ed. in English)》2023,62(25):e202306284
Solid-state lithium-metal batteries are considered as the next generation of high-energy-density batteries. However, their solid electrolytes suffer from low ionic conductivity, poor interface performance, and high production costs, restricting their commercial application. Herein, a low-cost cellulose acetate-based quasi-solid composite polymer electrolyte (C-CLA QPE) was developed with a high Li+ transference number ( ) of 0.85 and excellent interface stability. The prepared LiFePO4 (LFP)|C-CLA QPE|Li batteries exhibited excellent cycle performance with a capacity retention of 97.7 % after 1200 cycles at 1 C and 25 °C. The experimental results and Density Function Theory (DFT) simulation revealed that the partially esterified side groups in the CLA matrix contribute to the migration of Li+ and enhance electrochemical stability. This work provides a promising strategy for fabricating cost-effective, stable polymer electrolytes for solid-state lithium batteries. 相似文献