Effect of Alcohols on the Retention Mechanisms of Cd and Zn on Wyoming Bentonite and Illite
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- 作者：Rafif K. Srour and Louis M. Mcdonald
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：September 15, 2005
- 年：2005
- 卷：39
- 期：18
- 页码：7111 - 7117
- 全文大小：155K
- 年卷期：v.39,no.18(September 15, 2005)
- ISSN：1520-5851
文摘
The effects of ethanol- and methanol-water mixtures onZn and Cd sorption onto bentonite and illite wereinvestigated at low initial metal concentration (
10-5 M)and low ionic strength (2.5 mM Ca(NO3)2). For all cosolventfractions, the percent coverage of Zn and Cd to clayminerals was low (<5%) and independent of the solutiondielectric constant, 
, except for Zn at 10 
M. Cadmiumsorption to bentonite and illite was independent of . Zincsorption varied significantly between clay types, cosolventtype, and cosolvent fraction. The partitioning of Zn to bentoniteincreased from 0 to 10% alcohol-water fraction anddecreased after 10%. The same pattern was observed forthe partitioning of Zn on illite in methanol-water mixtures.In ethanol-water mixtures, Kf for Zn on illite increasedcontinuously from 0 to 50% ethanol. The decreased partitioningand hence mobility of Zn to bentonite and illite after 10%alcohol (only in methanol-water mixtures for illite) suggestsa potential environmental threat resulting from increasedtransport of this metal in subsurface environments wherethese cosolvents are present.
10-5 M)and low ionic strength (2.5 mM Ca(NO3)2). For all cosolventfractions, the percent coverage of Zn and Cd to clayminerals was low (<5%) and independent of the solutiondielectric constant, , except for Zn at 10 M. Cadmiumsorption to bentonite and illite was independent of . Zincsorption varied significantly between clay types, cosolventtype, and cosolvent fraction. The partitioning of Zn to bentoniteincreased from 0 to 10% alcohol-water fraction anddecreased after 10%. The same pattern was observed forthe partitioning of Zn on illite in methanol-water mixtures.In ethanol-water mixtures, Kf for Zn on illite increasedcontinuously from 0 to 50% ethanol. The decreased partitioningand hence mobility of Zn to bentonite and illite after 10%alcohol (only in methanol-water mixtures for illite) suggestsa potential environmental threat resulting from increasedtransport of this metal in subsurface environments wherethese cosolvents are present.