Adsorption of Cs(I) and Sr(II) on Bentonites with Different Compositions at Different pH

Izosimova, Y.; Gurova, I.; Tolpeshta, I.; Karpukhin, M.; Zakusin, S.; Zakusina, O.; Samburskiy; Krupskaya, V.

Авторы: Izosimova Y., Gurova I., Tolpeshta I., Karpukhin M., Zakusin S., Zakusina O., Samburskiy, Krupskaya V.
Журнал: Minerals
Том: 12
Номер: 7
Год издания: 2022
Первая страница: 1
Последняя страница: 15
Номер статьи: 862
DOI: 10.3390/min12070862
Аннотация: This paper deals with adsorption regularities and mechanisms of nonradioactive Cs(I) andSr(II) analogs on bentonites of different chemical and mineral composition from solutions of Cs andSr nitrates with pH 3, 7, and 10 units at constant ionic strength. The bentonites were taken from thedeposits Taganskoe (T), Dash-Salakhlinskoe (DS), Zyryanskoe (Z), and 10th Khutor (10H). The pH ofbentonite aqueous suspensions, T and DS, exceeded 9 units. A less alkaline reaction was observed inbentonite suspensions Z and T with pH 8.94 and 7.70, respectively. Bentonites T and DS containedsignificant amounts of nonsilicate iron compounds, 1.0 and 0.5%, respectively. The recovery rate of thestudied clays from aqueous solutions of Cs(I) and Sr(II) ions in concentrations from 0.25 to 5 mmol/Lvaried from 50% to 90% and decreased in the following order: “Ta-ganskoe” > “Dash-Salakhlinskoe” >“Zyryanskoe” > “10th Khutor” in the studied pH range. The main mechanism of Cs(I) and Sr(II)sorption in the studied pH range was cation fixation in the form of outer-sphere complexes on planarsurfaces resulting from ion exchange. Increasing pH (pH > 6) enhanced pH-dependent positions,which allowed Cs(I) and especially Sr(II) ions to fix on them more firmly as inner-sphere complexes.At pH 9–10, Sr(II) could precipitate in the form of carbonates. The sorption of Cs(I) + and Sr(II) wasaccompanied by competitive interactions with proton at pH < 6 and Na+, Ca2+, Mg2+, and K+ cationsat higher pH values. This competition was more apparent at concentrations of Cs(I)and Sr(II) ininitial solutions < 0.5 mmol/L. The ability of bentonite T to sorb Cs(I) and Sr(II) in large amountscompared to the other bentonites was determined by high CEC values and charge of smectite T
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Adsorption of Cs(I) and Sr(II) on Bentonites with Different Compositions at Different pHстатья

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