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Bentonite transformations in strongly alkaline solutions

journal contribution
posted on 2010-04-01, 00:00 authored by Will GatesWill Gates, A Bouazza
Strongly alkaline solution pH causes changes to the mineralogy of bentonites which might impact on their performance as environmental barriers. The long term effect of solution pH on the performance of bentonite barriers such as in Geosynthetic Clay Liners needs to be studied from the viewpoint of solubility and stability of the mineral phases present at extreme pH values. Changes to bentonite mineralogy brought about by extended reaction with 1 M sodium hydroxide solutions at 20–25 °C reveal that certain components of bentonites, namely smectite, opaline silica and quartz, are subject to dissolution in alkaline solution. Associated with dissolution is the formation of hydrous hydroxy-aluminosilicate as well as hydrous carbonate mineral phases. It is postulated that these precipitates, formed from reaction of bentonite with alkaline leachates can result in pore filling, which is responsible for recently measured lower hydraulic conductivity of some bentonites to high pH leachates.

History

Journal

Geotextiles and geomembranes

Volume

28

Issue

2

Pagination

219 - 225

Publisher

Elsevier

Location

London, Eng.

ISSN

0266-1144

eISSN

1879-3584

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2009, Elsevier

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