Journal
COLLOID AND POLYMER SCIENCE
Volume 297, Issue 7-8, Pages 979-987Publisher
SPRINGER
DOI: 10.1007/s00396-019-04532-3
Keywords
Morphology of flocs; Orientation; Floc strength; Na-montmorillonite; Laminar shear flow; Hydration force
Categories
Funding
- JSPS Kakenhi [16H06382]
- Grants-in-Aid for Scientific Research [16H06382] Funding Source: KAKEN
Ask authors/readers for more resources
The flowing behavior of montmorillonite flocs coagulated in NaCl solution was visualized using a device called Couette chamber which was designed to analyze the strength of floc against breakup in a laminar shear flow generated in the gap between two concentric cylinders. The rotation ax of cylinders was oriented horizontally to avoid the effect of sedimentation during measurement. Observation of the morphology of flowing flocs was performed with a high-speed camera under sufficiently high salt concentration to induce rapid coagulation of montmorillonite as a function of shear rate. The recorded image of flocs demonstrated that the average flowing flocs is approximated by an ellipsoid of equivalent inertial moment with a length ratio of two principal axes being around 2. The most probable orientation of the major axis was found to be the flow direction. Assuming flocs are ellipsoids and will be disrupted by the effect of extensional component of the flow field, the cohesive strength supporting the disintegrating clusters was calculated on the basis of the simple model of floc strength proposed previously for the breakup of a floc under turbulent flow. The tendency of structural enforcement by the rearrangement of internal clusters was recorded with an increase in size of floc irrespective of ionic strength. In addition, the enforcement of cohesive strength by the effect of dehydration of proximately adsorbed sodium ions at extremely high ionic strength was confirmed.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available