Kwang-Soon Choi

Separating Ag, B, Cd, Dy, Eu, and Sm in a Gd matrix using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester extraction chromatography for ICP-AES analysis

The separation procedure for Ag, B, Cd, Dy, Eu and Sm as impurities in Gd matrix using ICP-AES technique with an extraction chromatographic column has been developed. The spectral interference of the Gd matrix on the elements was eliminated using a chromatography technique with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) as the mobile phase and XAD-16 resin as the stationary phase. Ag(+), B(4)O(7)(2-), and Cd(2+) were eluted with 0.1M HNO(3), while rare earth ions were not. The best eluent for separating Eu and Sm in the Gd matrix was 0.3M HNO(3). The limit of quantitation for these elements was 0.6-3.0ng mL(-1). The recovery of Ag, B, and Cd was 90-104% using 0.1M HNO(3) as the eluent, while that of Eu, Gd, and Sm ranged from 100 to 102% with 0.3M HNO(3). Dy was recovered quantitatively with 4M HNO(3). The relative standard deviation of the methods for a set of three replicates was between 1.0 and 15.4% for the synthetic and standard Gd solutions. The proposed separation procedure was used to measure Ag, B, Cd, Dy, Eu, and Sm in a standard Gd solution.

Investigation of gaseous wet methyl iodide adsorption on Ag nanoparticles embedded in organic–inorganic hybrid silica gels

X-ray photoelectron spectroscopy (XPS), single-particle photoluminescence, and lifetimes were adopted to investigate the interaction properties between gaseous wet methyl iodide (CH3I) and Ag nanoparticles (Ag NPs), which are embedded into a propylethylenediamine (NH2CH2CH2NHCH2CH2CH2-, PEDA) anchored silica gel. Based on the obtained XPS resolutions and shifts of binding energies, a stronger interaction of CH3I than Ag NPs toward SiO2, methylation of amines and silanols by CH3I, the partial interaction in the Ag NPs and CH3I interface, condensation of SiO2 and PEDA, and stabilization of Ag NPs by PEDA were explained. In addition, an enhanced luminescence of Ag NP-embedded PEDA-anchored SiO2 gel (Ag NP-PEDA gel) by surrounding CH3I, and Ag NP stabilization by PEDA and CH3I were also observed from the single-particle photoluminescence and lifetimes.

Pertechnetate removal from aqueous solution using activated carbon modified with oxidizing and reducing agents

The adsorption mechanism of pertechnetate on activated carbon (AC) has been studied. For this work, the surface of commercial AC was modified using various oxidizing and reducing agents. The changes of surface functional groups were monitored by FT-IR spectroscopy and Boehm titration. The distribution coefficient (Kd) of TcO4− on the modified AC has been determined. In acidic media, the value of Kd slightly increased owing to the reductive treatment of ACs, whereas a large decrease in Kd was observed in case of oxidative treatment of ACs. Based on this work, the previous adsorption mechanisms for TcO4− on AC were examined. As an alternative adsorption mechanism, the adsorption by electrostatic attraction between TcO4− and protonated basic sites on AC surface was proposed.

Dissolution of vanadium pentoxide using microwave digestion system for determination of vanadium by ICP-AES

Dissolution procedure of vanadium pentoxide, which is widely used as a catalyst for production of sulfuric acid or an oxide reaction of the numerous organic compounds, was investigated. Reagent of vanadium pentoxide was completely dissolved in aqua regia--HF solution, but plate type of vanadium pentoxide sample was not clearly dissolved with mixed acids. Thus, in order to establish the dissolution procedure for plate type of vanadium pentoxide, the solubility of vanadium pentoxide was investigated through comparison of acid treatment-fusion and microwave digestion methods. The optimized acid for dissolution of vanadium compound was found to be mixing acids of aqua regia, and HF. Acid-fusion and microwave digestion methods have a similar property in the solubility of vanadium compound, but the latter was more quick and convenient procedure. The content of vanadium pentoxide was found to be using an inductively coupled plasma atomic emission spectrometer after dissolution of a sample with the microwave digestion system.