Deposition behavior of polystyrene latex particles on solid surfaces during migration through an artificial fracture in a granite rock sample

The deposition behavior of colloids during transport through heterogeneous media was observed by conducting column experiments to study migration of p olystyrene latex particles (diameter=309 run) through columns packed with a rtificially fractured granite rock (length=300 and 150mm). The experiments were conducted under conditions of different ionic strengths and flow rates . The results were similar to those for colloid deposition in columns packe d with glass beads reported previously; the colloid breakthrough curves sho wed three stages, characterized by different rates of change in the concent ration of effluent. Colloid deposition on the fracture surfaces was describ ed by considering strong and weak deposition sites. Scanning Electron Micro scopy (SEM) observations indicated the existence of strong and weak sites o n the fracture surfaces regardless of mineral composition. The observations also showed that the strong deposition sites tended to exist on surface ir regularities such as cracks or protrusions. The degree of colloid depositio n increased with increasing ionic strength and decreasing flow rate. The de pendencies on ionic strength and flow rate agreed qualitatively with the DL VO theory and the previous experimental results, respectively.