Advertisement

Clays and Clay Minerals

, Volume 3, Issue 1, pp 403–412 | Cite as

The Effect of Acid and Heat Treatment on Montmorillonoids

  • A. C. Mathers
  • S. B. Weed
  • N. T. Coleman
Article

Abstract

H-montmorillonite, -beidellite, and -nontronite were found to change spontaneously into Al-clays. Rates of conversion of H- to Al-clay were slow at 0°C, but at temperatures of around 100°C, moist H-montmorillonite changed to Al-saturated montmorillonite within 24 hours. It appeared that Al-ions moved from lattice positions to exchange positions, with octahedral Al moving more rapidly than tetrahedral Al.

Treatment of montmorillonoids with HCl solutions at 80°C resulted in the removal of large quantities of Fe, Mg, and Al. The residue after hot acid treatment appeared to be a mixture of essentially unaltered montmorillonoid and SiO2, rather than a new mineral.

On heat treatment, H- and Al-montmorillonites became largely non-expanding of 300°C, and lost the bulk of the CEC which could be attributed to permanent lattice charge, H- and Al-nontronite and -beidellite, on the other hand, did not suffer irreversible dehydration and loss of CEC until heated to sufficiently high temperatures to cause the expulsion of lattice OH. Montmorillonites with largely octahedral charge had smaller CEC’s after heating to 500°C than did montmorillonites with appreciable tetrahedral charge.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Coleman, N. T., and Harward, M.E. (1953) The heats of neutralization of acid clays and cation-exchange resins: Jour. Amer. Chem. Soc., vol. 75, pp. 6045–6046.CrossRefGoogle Scholar
  2. Earley, J. W., Osthaus, B. B., and Milne, I.H. (1953) Purification and properties of montmorillonite: Am. Mineral., vol. 38, pp. 707–724.Google Scholar
  3. Glasser, R. (1946) Effet du traitement acide sur la capacite d’échange de base de la montmorillonite: Comptes Rendus, vol. 222, pp. 1241–1242.Google Scholar
  4. Greene-Kelley, R. (1952) Irreversible dehydration of montmorillonite: Clay Min. Bull., vol. 1, pp. 221–227.CrossRefGoogle Scholar
  5. Grenall, A. (1949) Montmorillonite cracking catalyst: Indus. Eng. Chem., vol. 41, pp. 1485–1489.CrossRefGoogle Scholar
  6. Harward, M. E., and Coleman, N. T. (1954) Some properties of H- and Al-clays and exchange resins: Soil Sci., vol. 78, pp. 181–188.CrossRefGoogle Scholar
  7. Kerr, P. F., Main, M. S., and Hamilton, P. K. (1950) Occurrence and microscopic texamination of reference clay mineral specimens: API Preliminary Report No. 5.Google Scholar
  8. Schofield, R. K. (1939) The electrical charges on clay particles: Soils and Fertilizers, vol. 2, pp. 1–5.Google Scholar
  9. Thomas, C. L., Hickey, J., and Stecker, G. (1950) Chemistry of clay cracking catalysts: Indus. Eng. Chem., vol. 42, pp. 866–871.CrossRefGoogle Scholar

Copyright information

© The Clay Minerals Society 1954

Authors and Affiliations

  • A. C. Mathers
    • 1
  • S. B. Weed
    • 1
  • N. T. Coleman
    • 1
  1. 1.North Carolina State CollegeUSA

Personalised recommendations