Schematic of the apparatus designed for magnetic separation of layered silicates.
Magnetic particles stuck to the pole of a cylindrical magnet after of magnetic separation of hectorite. To exclude contact with the clay-water suspension, the magnet was carefully sealed using a polymer cylinder and polymer films.
(a) Magnetization and (b) temperature dependencies of M/H and of montmorillonite (MMT) as received and magnetically purified for 20 and . The inset of Fig. 3(a) shows magnetization of the same MMT samples measured at .
Volume ratio of hectorite (HCT) as received and magnetically purified depending on the time of magnetic separation; measurements were made by a simple magnetic susceptibility balance (MSB).
Temperature dependencies of (a) and (b) of hectorite (HCT) as received and magnetically purified for , , and . The dashed line in (b) shows the simulated linear vs dependence due to paramagnetic Fe ions in the lattice of HCT magnetically purified for .
Magnetization at (a) and (b) of hectorite (HCT) as received and magnetically purified for , , and .
Analysis of the magnetization of hectorite (HCT) magnetically purified for . The inset shows calculated diamagnetic and paramagnetic contributions arising from the diamagnetic HCT lattice and from Fe ions dispersed in this lattice, respectively.
A backscattered electron image of particles extracted from hectorite (HCT) by magnetic separation.
Magnetization of particles extracted from hectorite (HCT) by magnetic separation. The insets show (a) an expanded view of magnetization and demagnetization near zero magnetic field and (b) the temperature dependence of the magnetization of particles extracted from HCT.
MAS NMR spectra of hectorite (HCT) (a) as received, (b) magnetically purified for , and (c) magnetically purified mixed with of nanosize particles. The insets show expanded views of the spectra ( vertically). Experiments were run at spinning frequency of with probehead background suppression (see Ref. 20).
Intensity of MAS NMR spectra and of peaks in MAS NMR spectra of as-received and magnetically purified hectorite (HCT) vs content obtained by x-ray fluorescence analysis. Times of magnetic separation are indicated in the figure.
and NMR spectra of hectorite (HCT) [(a) and (c)] as-received and [(b) and (d)] magnetically purified for , and spectra of nanocomposites containing of poly(vinylalcohol) and of hectorite (HCT) (e) as received and (f) magnetically purified for . Refocused detection of the signal was used in (e) and (f) for signal enhancement.
Effect of magnetic separation on the composition of hectorite.
Paramagnetic susceptibility at and effective magnetic moments of MMT and HCT purified by magnetic separation.
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