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Experimental studies of the role of colloids in radioactive waste disposal are described. Attention has been focussed on the possible mechanisms of colloid transport and retention in aqueous media typical of those in a far field granitic geology. The characteristics and behaviour of natural colloids (derived from the sites at Fanay Augerès, France and Grimsel, Switzerland) and synthetic colloids (silica, iron oxide, fractions of clay and humic materials) are reported. These colloids have been characterised by a range of techniques (light scattering, photon correlation spectroscopy, electrophoresis, SEM, TEM, EDAX) to determine their structure, size and charge characteristics. The synthetic colloids, being well-defined model systems, have been studied extensively to determine their sorption properties and retention behaviour in contact with mineral surfaces of a type existing in granite geology. Retention is strong when the colloid and surface have different electrical charge, as with so-called "real colloids". When the colloids have a negative charge ("pseudocolloids") the interaction is much weaker. Quantitative determinations of retention capacities have been made using Rutherford backscattering spectroscopy (RBS), which has considerable promise in future studies of retention and migration mechanisms. The structure of humic acids may be described as aggregates of smaller units, possibly associated through hydrophobic interactions.

Additional information

Authors: BILLON A, CEA, Fontenay-aux-Roses (FR);ET AL., CEA, Fontenay-aux-Roses (FR);DELLA MEA G, University of Padua, Padova (IT);DRAN J C, CSNSM-CNRS, Orsay (FR);NICHOLSON S, AEA Technology, Harwell Laboratory, Didcot, Oxon. (GB);RAMSAY J D F, AEA Technology, Harwell Laboratory, Didcot, Oxon. (GB);RUSSELL P J, AEA Technology, Harwell Laboratory, Didcot, Oxon. (GB)
Bibliographic Reference: EUR 13506 EN (1991) 55 pp., FS, ECU 6.25
Availability: (2)
ISBN: ISBN 92-826-2663-6
Record Number: 199111004 / Last updated on: 1994-12-02
Original language: en
Available languages: en
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