ABSTRACT CTS-9702773 John Walz The effect of surface roughness on the interaction forces between colloidal particles and surfaces is a subject of great interest. Surface roughness is frequently given as a possible cause of the discrepancy between predicted and measured deposition rates in packed bed filtration experiments. Although numerous roughness models have been developed, no direct experimental measurement of the specific effect of roughness on the van der Waals or electrostatic interaction forces between surfaces has been obtained. The objectives of this research are to, (1) develop a general theoretical model for predicting the interaction forces between rough surfaces in which the mathematical description of the roughness is consistent with surface characterizations (e.g., SEM micrographs, AFM profiles); (2)measure experimentally the interaction energy profile between well-defined rough surfaces; and (3) measure the effect of surface roughness on the capture rate of particles flowing through a packed bed. The energy profile measurements will be obtained using the optical technique of total internal reflection microscopy (TIRM). Measurement of the effect of roughness on both the long range secondary energy minimum as well as the primary energy barrier will be made. The latter experiments are extremely useful since it is the height of the primary energy barrier which controls the rate of particle deposition in transport through porous media. The experimental procedure to be used will allow measuring specifically the effect of roughness on surface forces both with and without hydrodynamic effects. The educational objective is to improve the relationship between Tulane's chemical engineering department and the local oil and chemical industry. Such an improved relationship will, (1) provide better employment opportunities for our students; (2) provide increased financial support for our department; (3) improve the engineering education provided to our students; and (4) provide a valuable resource for supporting the local chemical engineering community.
