(A) study on the characteristics of activated carbon-zeolite mixed adsorbent for removal of aqueous radiotoxic nuclides = 액상 방사독성 핵종 제거를 위한 활성탄-제올라이트 혼합흡착제 특성 연구

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The simultaneous removal of cationic and anionic radiotoxic nuclides, such as $Cs^{137}$ and $I^{129}$, from aqueous solutions has been studied. As an adsorbent material, the mixture of activated carbon and chabazite zeolite was used. Chabazite zeolite is selected due to its high selectivity for $Cs^+$, and activated carbon due to its strong affinity for anions. Taking into account release rates of these nuclides from defected fuel rods as well as the inventories of radiotoxic cesium and iodine isotopes at discharge, it would be the most conservative assumption that the concentration of $I^-$ is at most 1% of that of $Cs^+$ in spent fuel storage basin water or low-level liquid wastes. Based upon this assumption, the mixture of 7:3 activated carbon-chabazite ratio in weight was found optimum for this reference concentration ratio f $Cs^+$ and $I^-$. Using this mixture of activated carbon and chabazite, he amount adsorbed until breakthrough points were estimated to be $0.62 \times 10^{-1}$ mol/kg for $Cs^+$ and $0.58\times 10^{-3}$ mol/kg for $I^-$. This conforms to the mole ratio of them in the feed solution. In order to investigate the adsorption mechanism and process conditions, equilibrium and kinetic studies as well as the column study were carried out. Surface analyses (SEM-EDAX,EPMA surface image scanning, and XPS) of chabazite and activated carbon show that the adsorption mechanisms of $Cs^+$ and $I^-$ is not due to the formation of any precipitates or crystallines at the surfaces of chabazite and activated carbon. From the equilibrium study, it was noticed hat $Cs^+$ specifically adsorbed onto the activated carbon surface caused a synergy effect on the adsorption of $I^-$. This phenomenon was experimentally verified with the column runs according to the packing types of a fixed bed. The effect of background electrolytes, namely Na+ and $Cl^-$,on the $Cs^+$ isotherm s minute over the whole range of equilibrium concentration, whereas that on the $...
Advisors
Lee, Kun-Jairesearcher이건재researcher
Description
한국과학기술원 : 원자력공학과,
Publisher
한국과학기술원
Issue Date
1997
Identifier
128189/325007 / 000865208
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 원자력공학과, 1997.8, [ xiii, 132 p. ]

Keywords

Iodine; Cesium; Mixed adsorbent; Zeolite; Activated caron; Fixed bed; 고정층; 요오드; 세슘; 혼합흡착제; 제올라이트; 활성탄

URI
http://hdl.handle.net/10203/48874
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=128189&flag=dissertation
Appears in Collection
NE-Theses_Ph.D.(박사논문)
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