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The effect of UV-C irradiation and EDTA on the uptake of Co2+ by antimony oxide in the presence and absence of competing cations Ca2+ and Ni2+

Leena Malinen,Eveliina Repo,Risto Harjula,Nina Huittinen 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.2
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  ScienceON
  
  KCI
In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste isneeded to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organiccomplexing agents such as EDTA cobalt removal can be problematic due to the high stability of the CoEDTA complex. In this study, the removal of cobalt from NaNO3 solutions using antimony oxide (Sb2O3)synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence ofEDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UVlight) and under UV-C irradiation. Ca2þ or Ni2þ were included in the experiments as competing cations totest the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances thecobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption ofcobalt to a higher extent than calcium. Finally, the sorption data collected for Co2þ on antimony oxidewas modeled using six different isotherm models. The Sips model was found to be the most suitablemodel to describe the sorption process. The Dubinin-Radushkevich model was further used to calculatethe adsorption energy, which was found to be 6.2 kJ mol1
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제올라이트 Y (Si/Al = 1.56) 골격 내의 Ca2+과 Cs+ 이온의 자리 경쟁 및 그들의 결정학적 연구

김후식 ( Hu Sik Kim ),박종삼 ( Jong Sam Park ),임우택 ( Woo Taik Lim ) 한국광물학회 2018 광물과 암석 (J.Miner.Soc.Korea) Vol.31 No.4
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 ScienceON
 
 코리아스칼라
 
 KISS
본 연구는 제올라이트 Y (Si/Al = 1.56)에서 Cs+ 이온 교환에 Ca2+ 이온의 경쟁 양이온 효과를 연구하기 위해 수행되었다. 완전히 탈수되고 부분적으로 Cs+ 이온으로 교환된 3개의 제올라이트 Y(Si/Al = 1.56)의 단결정은 혼합이온교환 용액을 사용하여 흐름법으로 제조되었으며, 전체 농도가 0.05M인 이온교환용액의 CsNO3 : Ca(NO3)2 몰비는 1 : 1 (Crystal 1), 1 : 100 (Crystal 2) 및 1 : 250 (Crystal3)이다. 이온교환된 단결정을 723 K에서 2일 동안 1 × 10-4 Pa로 진공 탈수시켰으며, 결정구조는 100(1) K에서 입방공간군 Fd3m을 사용하여 단결정 싱크트론 X선 회절법으로 해석하고 구조를 정밀화하였다. Crystal 1, 2 및 3의 단위세포당 화학식은 |Cs21Ca27|[Si117Al75O384]-FAU, |Cs2Ca36.5|[Si117Al75O384]-FAU 및 |Cs1Ca37|[Si117Al75O384]-FAU이다. 3개의 결정 모두에서, Ca2+ 이온은 D6Rs 내의 site I을 우선적으로 점유하고 있으며 나머지는 site I’, II’ 및 II를 점유하고 있다. 한편 주어진 이온교환용액의 초기 Cs+ 이온의 농도에 따라 Cs+ 이온의 분포에 중요한 차이가 관찰되었다. Crystal 1에서는 Cs+ 이온이 site II’, II, III와 III’에 위치하고 있으며, Crystal 2에서는 site II, IIIa, IIIb에 위치하고 있다. Crystal 3에서는 Cs+ 이온은 site IIIa 및 IIIb에만 위치하고 있다. 초기 Ca2+ 이온의 농도가 증가하고 Cs+ 이온의 농도가 감소에 따라 Cs+ 이온의 교환정도는 28.0에서 2.7과 1.3 %로 급격히 감소하였다. The present work was performed in order to study the effect of competing cation of Ca2+ ion on ion exchange of Cs+ on zeolite Y (Si/Al = 1.56). Three single-crystals of fully dehydrated and partially Cs+-exchanged zeolites Y (Si/Al = 1.56) were prepared by the flow method using mixed ion-exchange solutions. The CsNO3 : Ca(NO3)2 molar ratios of the ion exchange solution were 1 : 1 (crystal 1), 1 : 100 (crystal 2), and 1 : 250 (crystal 3) with a total concentration of 0.05 M. The single-crystals were then vacuum dehydrated at 723 K and 1 × 10-4 Pa for 2 days. The structures of the crystals were determined by single-crystal synchrotron X-ray diffraction technique in the cubic space group Fd3m, at 100(1) K. The unit-cell formulas of crystals 1, 2, and 3 were |Cs21Ca27|[Si117Al75O384]-FAU, |Cs2Ca36.5|[Si117Al75O384]-FAU, and |Cs1Ca37|[Si117Al75O384]-FAU, respectively. In all three crystals, the Ca2+ ions preferred to occupy site I in the D6Rs, with the remainder occupying sites I’, II’, and II. On the other hand, the significant differences in the fractional distribution of Cs+ ions are observed depending on the intial Cs+ concentrations in given ion exchange solution. In Crystal 1, Cs+ ion are located at sites II’, II, III, and III’, and in crystal 2, at sites II, IIIa, and IIIb. In crystal 3, Cs+ ions are only located at sites IIIa and IIIb. The degree of Cs+ ion exchange decreased sharply from 28.0 to 2.7 to 1.3 % as the initial Ca2+ concentration increases and the Cs+ content decreases.

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