Impact of the Salt Concentration and Biophysical Cohesion on the Settling Behavior of Bentonites

The flocculation behavior of clay minerals in aquatic environments is an important process estuarine and riverine dynamics, where strong gradients salinity can locally occur. Various contradicting observations have been reported the literature on impact salt concentration settling cohesive sediments. To address this issue a systematic manner, we investigate as function ambient water. Specifically, focus montmorillonite prototype mineral with high cation exchange capacity (CEC). end, study suspensions Wyoming bentonite (Volclay SPV) very constituent for many constructional industrial purposes. We perform experimental campaign to moderately turbid concentrations monovalent solutions different salinities (sodium chloride) represent ranging from deionized ocean water, respectively. subsequent was monitored by taking pictures camera regular time intervals over total observation up 48 h. In addition, modified hydrometer analysis conducted determine grain size distribution (in terms equivalent diameter) flocculated suspension Despite rather investigated (CEC=88.1), our results show that speed drastically increases within range 0.6–1.0 PSU stays approximately constant higher salinities. This critical defined here coagulation (CCC) lies well below natural open water bodies. revealed 60% agglomerates exceed 20 μm. Finally, findings are supplemented experiments studying effect Extracellular Polymeric Substances (EPS) Our demonstrate original trigger flocculation, whereas EPS allows even larger floc but it does not play significant role processes environments.