ATOMIC STRUCTURE AND CRYSTAL CHEMISTRY OF CLAYS USED IN REMEDIATION OF HAZARDOUS WASTE

S. Sivalingam

TapanAm Associates, 8010 State Line Road, Leawood, KS, 66208, 913-648-5411


ABSTRACT

Clays are widely used in the environmental industry as impermeable barriers, adsorbents, molecular sieves and for stabilization of hazardous wastes. Impermeable barriers using bentonite include landfill liners and caps, geocomposite liners, slurry walls, seals in monitoring wells, and as barriers surrounding radioactive waste canisters. The common clay minerals identified include smectite (bentonite), vermiculite, attapulgite and sepiolite. These clays are especially important because of their micron sized particles, swelling properties (especially in bentonite), large surface areas, high cation exchange capacity, chemical stability, charge distribution, unique atomic structure and widespread occurrence.

Fundamentals of diffuse double layer, mineral-surface-complexation and current research in organo-clay complexation and pillared clays with respect to hazardous waste remediation will be discussed.

Results of analytical electron microscopy (quantitative thin film X-ray microanalysis, selected area electron diffraction) and X-ray diffraction to characterize the chemical composition and crystal structure of these common clays will be presented.

KEY WORDS

clays, remediation, atomic structure, microscopy

This paper is from the Proceedings of the 10th Annual Conference on Hazardous Waste Research 1995, published in hard copy and on the Web by the Great Plains/Rocky Mountain Hazardous Substance Research Center.