Ultrasonic slurry example

Preparation of an ultrasonic slurry of the sample is occasionally used, as for example in the determination of cobalt, nickel and copper [200], selenium [39] and arsenic and antimony [40]. Extraction of leaves with a chloroform solution of xanthate completely extracted cadmium [41,103]. X-ray fluorescence spectroscopy is a nondestructive method of analysing plant materials if they can be converted into a suitable form for presentation to the instrument. 

For example for the preparation of a 15 cm long, 4.6 mm i.d. stainless tube column, 2.5 g of octadecyl-bonded silica gel was suspended in 25 ml of hexanol-methanol mixture, and kept in an ultrasonic bath for a few minutes to remove air. After the reservoir was filled with the slurry, methanol was pumped in at 10 ml min -1 under constant pressure, 45 MPa (450 bar). After the replacement of slurry solvent by methanol, the flow was stopped and the pressure allowed to drop. When 0 MPa was reached the reservoir was removed. Then, 20 ml of water was added and methanol was again pumped in under the same conditions as before. Again, the flow was stopped and the pressure allowed to drop until it reached 0 MPa. The pre-column was removed and the analytical column closed. The maximum pressure that can be applied in the filling stage is based on the pore size, particle shape, and purity of the silica gel. This reproducible packing procedure is performed at constant temperature by using a water bath (60-BO °C). 

Another concern is shedding. The sonication probe tip, normally made of titanium, can suffer from pitting and erosion during use. One commercial solution to this problem is to use a secondary fluid to carry the ultrasonic waves to the product slurry container, as occurs with, for example, glass or metal containers in an ultrasonic bath. 

There are reports indicating that metal adsorption and dispersion can be enhanced by applying ultrasound during impregnation. For example, a slurry of the fine carbon particles prepared by ultrasonic radiation was mixed with the aqueous solution of the active metal precursors.The resultant catalyst was dried at 383 K. This was followed by reduction at 473 K before the catalyst was used for coal liquefaction. 

The rate of diamond nucleation on untreated, smooth substrates is routinely low. Therefore, substrate pretreatment is a prerequisite for diamond deposition. A common method of pretreating substrates is to seed the surface by either mechanically polishing with a small diameter diamond powder (0.01-1 pm diameter) or ultrasonicating the substrate in a diamond powder/solvent slurry. For example, the diamond powder can be... 

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