Effect of solution composition on the recrystallization of kaolinite to feldspathoids in hyperalkaline conditions: limitations of pertechnetate incorporation by ion competition effects

Janice Littlewood, Samuel Shaw, Pieter Bots, Caroline L. Peacock, Divyesh Trivedi, Ian T. Burke

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The incorporation of pertechnetate (TcO4-) into feldspathoids produced by alkaline alteration of aluminosilicate clays may offer a potential treatment route for 99Tc-containing groundwater and liquors. Kaolinite was aged in NaOH to determine the effect of base concentration, temperature, and solution composition on mineral transformation and pertechnetate uptake. In all reactions, increased temperature and NaOH concentration increased the rate of kaolinite transformation to feldspathoid phases. In reactions containing only NaOH, sodalite was the dominant alteration product; however, small amounts (6-15%) of cancrinite also formed. In experiments containing NaOH/Cl and NaOH/NO3 mixtures, sodalite and nitrate cancrinite were crystallized (at 70°C), with no reaction intermediates. The addition of SO42- crystallized sulfatic sodalite at 40 and 50°C, but at higher temperatures (60 and 70°C) sulfatic sodalite transforms to vishnevite (sulfatic cancrinite). In experiments where a pertechnetate tracer was added (at ~1.5 μmol l-1), only 3-5% of the 99Tc was incorporated into the feldspathoid phases. This suggests that the larger pertechnetate anion was unable to compete as favourably for the internal vacancies with the smaller OH-, NO3-, SO42- or Cl- anions in solution, making this method likely to be unsuitable for groundwater treatment.
LanguageEnglish
Pages1379-1388
Number of pages10
JournalMineralogical Magazine
Volume79
Issue number6
DOIs
Publication statusPublished - 1 Nov 2015

Fingerprint

Kaolin
sodalite
Sodium Pertechnetate Tc 99m
cancrinite
kaolinite
Ions
ion
Chemical analysis
Anions
anion
Groundwater
Reaction intermediates
groundwater
aluminosilicate
Nitrates
Temperature
Vacancies
Minerals
transform
experiment

Keywords

  • alkaline
  • alteration
  • crancrinite
  • kaolinite
  • pertechetate
  • sodalite

Cite this

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title = "Effect of solution composition on the recrystallization of kaolinite to feldspathoids in hyperalkaline conditions: limitations of pertechnetate incorporation by ion competition effects",
abstract = "The incorporation of pertechnetate (TcO4-) into feldspathoids produced by alkaline alteration of aluminosilicate clays may offer a potential treatment route for 99Tc-containing groundwater and liquors. Kaolinite was aged in NaOH to determine the effect of base concentration, temperature, and solution composition on mineral transformation and pertechnetate uptake. In all reactions, increased temperature and NaOH concentration increased the rate of kaolinite transformation to feldspathoid phases. In reactions containing only NaOH, sodalite was the dominant alteration product; however, small amounts (6-15{\%}) of cancrinite also formed. In experiments containing NaOH/Cl and NaOH/NO3 mixtures, sodalite and nitrate cancrinite were crystallized (at 70°C), with no reaction intermediates. The addition of SO42- crystallized sulfatic sodalite at 40 and 50°C, but at higher temperatures (60 and 70°C) sulfatic sodalite transforms to vishnevite (sulfatic cancrinite). In experiments where a pertechnetate tracer was added (at ~1.5 μmol l-1), only 3-5{\%} of the 99Tc was incorporated into the feldspathoid phases. This suggests that the larger pertechnetate anion was unable to compete as favourably for the internal vacancies with the smaller OH-, NO3-, SO42- or Cl- anions in solution, making this method likely to be unsuitable for groundwater treatment.",
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Effect of solution composition on the recrystallization of kaolinite to feldspathoids in hyperalkaline conditions : limitations of pertechnetate incorporation by ion competition effects. / Littlewood, Janice; Shaw, Samuel; Bots, Pieter; Peacock, Caroline L.; Trivedi, Divyesh; Burke, Ian T.

In: Mineralogical Magazine, Vol. 79, No. 6, 01.11.2015, p. 1379-1388.

Research output: Contribution to journalArticle

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T1 - Effect of solution composition on the recrystallization of kaolinite to feldspathoids in hyperalkaline conditions

T2 - Mineralogical Magazine

AU - Littlewood, Janice

AU - Shaw, Samuel

AU - Bots, Pieter

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AU - Trivedi, Divyesh

AU - Burke, Ian T.

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