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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 14, Number 1
JKCSEZ 14(1)
February 20, 1970 

Citrate Complexes of Alkaline Earth Metals in Aqueous, Acetone-Water and Ethanol-Water Solutions

수용액, 물-아세톤 및 물-에탄올 혼합 용매 내에서 형성되는 알칼리토류금속의 시트르산 착물
Sang Up Choi, Young Il Par, Won Mok Jae

최상업, 배영일, 제원목
양이온 교환수지와 시트르산 이온(Cit3-)이 들어있는 용액에서 방사성 알칼리 토류 금속 이온이 수지와 용액 사이에 어떻게 분배되는가를 실온에서 조사함으로써 그들 금속 이온의 시트르산 착물형성에 관한 연구를 하였다. 용매로서 H2O, 아세톤-H2O 및 에탄올-H2O를 사용하였다. 용액의 pH는 7.2-7.5로 조절하였고 이온 강도는 0.10-0.12로 유지하였다. 본 연구의 결과 Ba++과 Sr++은 어떤 용매계에서도 1:1착물(M Cit-)을 형성하는 것을 알았다. 그리고 Ca++은 수용액에서는 1:1착물을 형성하지만 혼합 용매계에서는 1:1착물(Ca Cit-)과 1:2착물(Ca Cit4-)을 형성함을 알았다. 그리고 이들 착물의 안정도는 Ba++ < Sr++ < Ca++ 의 순으로 커지며 또 혼합용매의 유기 성분의 농도 증가순으로 커짐을 알았다.

Formation of the complexes of alkaline earths with citrate ions in aqueous, acetone-water and ethanol-water solutions was studied at room temperature by the equilibrium exchange technique. This technique involved the measurements of distribution of radioactivity between cation exchange resin and solution phase after the radioactive metal ions were equilibriated with the cation exchange resin in the presence of citrate ions (Cit3-) of varying concentrations. The pH of the solutions was controlled to 7.2-7.5, and the ionic strength of the solutions was kept at 0.10-0.12. The present study revealed that both barium and strontium ions formed the one to one citrate complexes, [M Cit]- in all solvent systems examined. It was also observed that calcium ions formed the one to one citrate complex in aqueous solution. In acetone-water and ethanol-water solutions, however, calcium ions were observed to form both one to one and one to two complexes, [Ca Cit]- and [Ca Cit2]4-. The results of the present study indicated also that relative stabilities of the complexes increased in the order; Ba++ < Sr++ < Ca++, and in the order of increasing concentration of the organic components in the mixed solvent systems.

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