The U.S. Bureau of Mines has developed a method of dewatering clay slurries by addition of polyethylene oxide (peo) solution followed by mechanical deformation of the flocs in a trommel to remove water. Quantitative infrared spectroscopy was used to measure the amount of peo adsorbed on eight different ion-exchanged montmorillonite clays (k, nh4, na, li, sr, ba, ca, and mg). It was determined that the amount of peo adsorbed, a, the electronegativity, e, and the distance, r, between the ether group of the peo and the exchange ion of the clay are described by the relationship a = ke/r. The value of k is constant for a given initial polymer solution concentration. The value adopted for r is the sum of the radius of the exchange ion, the radius of the ether group, and the diameter of either two or three water molecules. This observation is compatible with the conventional view that polymer adsorption occurs through a water bridge.
Flocculation & Dewatering, Proc. Eng. Foundation Conf., Palm Coast, Florida, 1/10-15/88, Pp 577-586