Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Study of Ni(II) sorption on chlorite - a fracture filling mineral in granites
KTH, Superseded Departments, Chemistry.
KTH, Superseded Departments, Chemistry.
KTH, Superseded Departments, Chemistry.
2004 (English)In: 28th Symposium on the Scientific Basis for Nuclear Waste Management held at the 2004 MRS Spring Meeting San Francisco, CA, APR 13-16, 2004, 2004, Vol. 824, 373-378 p.Conference paper, Published paper (Refereed)
Abstract [en]

Chlorite is an Fe(II)-containing phyllosilicate which is often present as a fracture filling mineral in e.g. granitic rocks. It may therefore be significant in influencing redox conditions and sorption processes in granitic groundwaters. The sorption properties of chlorite may therefore be important when modelling the migration of radionuclides under reducing conditions around nuclear waste repositories or in sites contaminated by mining waste. The sorption behaviour of Ni(II) onto a natural chlorite (Karlsborg, Sweden) was investigated using a batch technique. The effects of three different background electrolyte concentrations (0.01 M, 0.1 M and 0.5 M NaClO4) different pH values (ranging from 4 to 11) and different Ni(II) concentrations (10(-6) and 10(-8) M) were studied under anoxic conditions in a glove-box. Ni(II) solutions were spiked with 63 Ni and beta-Liquid scintillation counting (LSC) was used to determine the concentration of nickel in the bulk solution, allowing the calculation of solid-water distribution coefficients for the metal ion. The results of the sorption experiments show strong pH dependence at pH > 5, but the sorption is independent of ionic strength. The maximum adsorption is found in the pH range between 7 and 11 with K-d values approximate to10(3) cm(3)/g. A diffuse double layer model has been used to describe the experimental results.

Place, publisher, year, edition, pages
2004. Vol. 824, 373-378 p.
Series
Materials research society symposium proceedings, ISSN 0272-9172
National Category
Other Basic Medicine
Identifiers
URN: urn:nbn:se:kth:diva-24160ISI: 000224543500056Scopus ID: 2-s2.0-14944372867OAI: oai:DiVA.org:kth-24160DiVA: diva2:344368
Note
QC 20100819Available from: 2010-08-19 Created: 2010-08-19 Last updated: 2011-10-31Bibliographically approved
In thesis
1. Chlorite: Geochemical properties, Dissolution kinetcis and Ni(II) sorption
Open this publication in new window or tab >>Chlorite: Geochemical properties, Dissolution kinetcis and Ni(II) sorption
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In Sweden, among other countries, a deep multi-barrier geological repository, KBS-3, is planned for the burial of nuclear waste. One of the barriers is identified as the grantic bedrock itself and in this environment chlorite is present at surfaces in fracture zones.

This thesis is focused on characterisation of chlorite samples and studies of their dissolution and sorption behaviour, in order to verify chlorites capacity to retard possible radionuclide migration in the case of leaking canisters.

Chlorite dissolution of has been studied in the pH interval 2-12, and as expected the dissolution is highest at acidic pH and at most alkaline pH, whereas dissolution is lowest at near neutral pH values. Chemical and physical properties of chlorites clearly influence the dissolution rates, and at steady-state dissolution rates in the interval 10-12 ‑ 10-13 mol g-1 s-1 was observed.

Sorption studies were performed since Ni(II) is one of the important activation products in spent nuclear fuel and sorption data on minerals like chlorite are lacking. Ni(II) sorption onto chlorite was studied using batch technique as a function of; pH, concentration of Ni(II), ionic strength and solid concentrations. As expected, the sorption of Ni(II) onto chlorite was pH dependent, but not ionic strength dependent, with a sorption maximum at pH ~ 8, and with a Kd of ~ 103 cm3/g. This confirms that the Ni(II) sorption onto chlorite is primarily acting through surface complexation. The acid-base properties were determined by titrations and described by a non-electrostatical surface complexation model in FITEQL. Further, the sorption results were fit with a 2-pK NEM model and three surface complexes, Chl_OHNi2+, Chl_OHNi(OH)+ and Chl_OHNi(OH)2, gave the best fit using FITEQL.

Abstract [sv]

Sverige är ett av de länder som planerar ett geologiskt slutförvar kallad KBS-3, bestående av ett antal barriärer, för placering utav det använda kärnbränslet. En av dessa barriärer är identifierad som själva berggrunden där det tilltänkta förvaret kommer att byggas och i denna miljö förekommer klorit på granitytor i sprickzoner.

Denna doktorsavhandling karakteriserar kloriter och studerar deras upplösnings- och sorptionsbeetende, för att kunna bestämma huruvida kloriter är utav betydelse som naturlig barriär för eventuell radionuklidtransport från det använda kärnbränslet.

Upplösning av klorit har undersökts i pH intervallet 2-12 och graden av upplösningen är som förväntat högst vid sura respektive mest basiska pH och lägst där pH är neutralt. Denna studie bekräftar att den kemiska sammansättning och de fysikaliska egenskaper hos kloriterna påverkar upplösningshastigheterna och vid steady‑state har upplösningshastighet bestämts till 10-12 ‑ 10-13 mol g-1 s-1.

Sorptionsstudier genomfördes då Ni(II) är en viktig aktiveringsprodukt och data rörande Ni(II) sorption till klorit saknas. Ni(II) sorption till klorit har studerats i; varierande pH, olika initiala Ni(II) koncentrationen, olika jonstyrka och olika fastfas förhållanden där individuella satser i serie har nyttjats. Som förväntat är sorptionen av Ni(II) till klorit pH beroende men inte jonstyrkeberoende och ett sorpions maximum observerades vid pH ~ 8, med ett Kd‑värde på ~ 103 cm3/g. Från detta dras slutsatsen att sorptionen av Ni(II) till klorit sker mestadels genom ytkomplexering. Syra-bas egenskaperna hos kloriterna bestämdes genom titreringar och bekrevs med en icke‑elektrostatisk modell i FITEQL. Vidare har passning av sorptionsresultaten utförts med en 2-pK NEM-modell och tre ytkomplex, Chl_OHNi2+, Chl_OHNi(OH)+ och Chl_OHNi(OH)2, vilket gav den bästa passningen av data med FITEQL.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. xii, 81 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2009:9
Keyword
chlorite, dissolution kinetics, Ni(II) sorption, surface complexation
National Category
Other Basic Medicine
Identifiers
urn:nbn:se:kth:diva-10139 (URN)978-91-7415-247-0 (ISBN)
Public defence
2009-04-24, D2, Lindstedsvägen 5, entreplan, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100819Available from: 2009-05-05 Created: 2009-03-25 Last updated: 2010-08-19Bibliographically approved

Open Access in DiVA

No full text

Scopus

Search in DiVA

By author/editor
Gustafsson, ÅsaMolera, MireiaPuigdomenech, Ignasi
By organisation
Chemistry
Other Basic Medicine

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 73 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf