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Description
A new supramolecular composition containing a clozoborane salt UO2 [ B10H9S(C18H39)]2 ,
polyvinyl chloride (PVC) as a matrix and tris (2-ethylhexyl) phosphate. The membranes of various compositions with different ratios of membrane components were investigated.
The membrane with the best electroanalytical characteristics has the following composition:
Сs B10H9S(C18H37)2 : 1 – 3 % (mass),
tris (2-ethylhexyl) phosphate: 65 – 72 %
PVC: 27 – 32 %
The developed electrode had a linear potential dependence in the range not worse than pUO22+ = 2 – 6, The detection limit for uranyl ions was C(UO22+) = 1,6*10 -7 М. The measured selectivity factors are given in the table:
Anion Cs+ Rb+ K+ Na+ Sr2+ Ca2+ Mg2+
Кselect 8•10-5 8,2•10-5 9•10-5 1,1•10-4 3,0•10-5 1,05•10-4 2,2•10-5
As follows from the values of the selectivity coefficients, the developed electrode showed a very high selectivity with respect to uranyl ions in the presence of alkaline and basic alkaline earth cations.
From the analysis of selectivity data, it should be noted that the behavior of the proposed supramolecular system does not obey the Hofmeister series. It has been established that even 10 + 4-fold excesses of alkali and alkaline earth ions do not significantly affect the membrane potential. The established series of selectivity series looked as follows:
UO22+ > Li+ > Na > K > Cs > Ca > Mg
