Mobilization of Lead from Highly Weathered Porous Material by Extracting Agents
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- 作者：Vijay M. Vulava and John C. Seaman
- 刊名：Environmental Science & Technology
- 出版年：2000
- 出版时间：November 15, 2000
- 年：2000
- 卷：34
- 期：22
- 页码：4828 - 4834
- 全文大小：86K
- 年卷期：v.34,no.22(November 15, 2000)
- ISSN：1520-5851
文摘
Batch and dynamic leaching experiments were conductedto evaluate the influence of clay mineralogy and soilorganic matter (SOM) present in two highly weathered,surface and subsurface soil materials on Pb sorption andsubsequent extraction using ethylenediaminetetraaceticacid (EDTA) and carboxymethyl 
chars/beta2.gif" BORDER=0 ALIGN="middle">-cyclodextrin (CMCD).Saturated soil columns were leached with an acidic Pbsolution to simulate a contamination event, followedby injection of artificial groundwater (AGW) at constantvelocity. Greater Pb retardation was observed within thesurface soil compared to the subsurface soil material, anda significant increase in effluent turbidity was observedcoincident with the Pb breakthrough in the subsurface soilmaterial. Electrophoretic, thermo-gravimetric, and X-raydiffraction analysis of the resulting suspension suggestedthat the presence of strongly adsorbing Pb2+ and excessH+ increased the positive charge on amphoteric mineralsurfaces and reduced the negative charge on clay minerals,which induced selective dispersion and transport of Feoxides. In contrast, no increase in turbidity was observedfor the surface soil following Pb injection. While only30% of adsorbed Pb was mobilized from contaminatedsubsurface soil material, less than 10% of adsorbed Pb wasextracted from surface soil when Pb-contaminated soilcolumns were flushed with AGW. Following leaching withAGW, extraction solutions containing either 0.37 g L-1 (1mM) EDTA or 10 g L-1 CMCD were applied to extract theresidual bound Pb. Nearly 100% of residual Pb wasextracted from the surface soil by EDTA as compared toabout 56% removal by CMCD under similar conditions. About80% of residual Pb was removed by EDTA from the Pb-contaminated subsurface material, but less than 2% of residualPb was extracted by CMCD under similar conditions.
chars/beta2.gif" BORDER=0 ALIGN="middle">-cyclodextrin (CMCD).Saturated soil columns were leached with an acidic Pbsolution to simulate a contamination event, followedby injection of artificial groundwater (AGW) at constantvelocity. Greater Pb retardation was observed within thesurface soil compared to the subsurface soil material, anda significant increase in effluent turbidity was observedcoincident with the Pb breakthrough in the subsurface soilmaterial. Electrophoretic, thermo-gravimetric, and X-raydiffraction analysis of the resulting suspension suggestedthat the presence of strongly adsorbing Pb2+ and excessH+ increased the positive charge on amphoteric mineralsurfaces and reduced the negative charge on clay minerals,which induced selective dispersion and transport of Feoxides. In contrast, no increase in turbidity was observedfor the surface soil following Pb injection. While only30% of adsorbed Pb was mobilized from contaminatedsubsurface soil material, less than 10% of adsorbed Pb wasextracted from surface soil when Pb-contaminated soilcolumns were flushed with AGW. Following leaching withAGW, extraction solutions containing either 0.37 g L-1 (1mM) EDTA or 10 g L-1 CMCD were applied to extract theresidual bound Pb. Nearly 100% of residual Pb wasextracted from the surface soil by EDTA as compared toabout 56% removal by CMCD under similar conditions. About80% of residual Pb was removed by EDTA from the Pb-contaminated subsurface material, but less than 2% of residualPb was extracted by CMCD under similar conditions.© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |