Open AccessAn environmental scanning electron microscopy study of aqueous gibbsite suspensions
Author(s) -
Houghton H.A.,
Donald A.M.
Publication year - 2008
Publication title -
scanning
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.359
H-Index - 47
eISSN - 1932-8745
pISSN - 0161-0457
DOI - 10.1002/sca.20111
Subject(s) - gibbsite , environmental scanning electron microscope , scanning electron microscope , dispersion (optics) , chemistry , chemical engineering , aqueous solution , lithium (medication) , evaporation , analytical chemistry (journal) , materials science , mineralogy , optics , composite material , environmental chemistry , meteorology , physics , medicine , endocrinology , kaolinite , engineering
Synthetic gibbsite has been used as a model system for study in the environmental scanning electron microscopy (ESEM), to probe its utility as a tool to study clay dispersions under different conditions of aggregation. We have been able to show that we can study the nature of the platelet interactions as the pH is altered, by imaging the dispersions after water evaporation from the surface to permit the surface of the platelets to be clearly seen. It has been possible to show that at alkaline pH there are very few face–edge contacts between the platelets, consistent with what is known about the charges at high pH on the faces and edges of the gibbsite. In contrast, at lower pHs, when faces and edges have opposite sign charges, there are significantly more platelets touching with edge and faces in contact. Finally, when the salt lithium chloride is added to a dispersion at approximately neutral pH, the plates appear to stack suggesting face–face interactions in the dispersion. Thus, ESEM has been able to demonstrate the variability of packing in gibbsite dispersions and to correlate the structures observed with the known charge distribution on the gibbsite platelets. SCANNING 30: 223–227, 2008. © 2008 Wiley Periodicals, Inc.