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Polymer flocculation is commonly used to remove colloidal material from solution, improving separation performance. The structure of the mesoscale formation (floc) affects process performance, as well as the amount of polymer required. By visualizing polymer in flocs using fluorescently-tagged polymers and laser confocal microscopy, we directly observe effects of ionic strength on polymer-clay floc internal structure. At low ionic strength, I < 10 mM NaCl, the polymer forms a continuous, interconnected internal network, whereas at high ionic strength, the polymer no longer forms this network and simply coats the larger bentonite aggregates. This method offers the ability to visualize the polymer structure without drying or freezing the solution, making it ideal for observation of delicate aggregates. While especially applicable to water purification, the structure observations shown here yield important fundamental insights for polymer adsorption dynamics onto inorganic heterogeneous particulate or surface structures.
Bibliographical noteFunding Information:
This work was supported primarily by the National Science Foundation through the University of Minnesota MRSEC under award number DMR-1420013 . This work was supported partially by the Research Experiences for Undergraduates (REU) Program of the National Science Foundation under award number DMR-1263062 . Parts of this work were carried out in the Minnesota Nano Center which receives partial support from NSF through the NNIN program . This research was conducted with Government support under and awarded by the Department of Defense, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship , 32 CFR 168a .
- Water Treatment
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- Period 3