Nondispersive systems

Low Solids/Nondispersed. Fresh water, clay, and polymers for viscosity enhancement and filtration control make up low sohd/nondispersed muds. Low soflds muds are maintained using minimal amounts of clay and require removal of all but modest quantities of drill soflds. These are called nondispersed systems because no additives are used to further disperse or deflocculate the viscosity building clays. Most water-based muds are considered dispersed because deflocculating additives are used to control the flow properties. 

Low Solids Muds—Nondispersed Systems. These muds contain less than 3-6% solids by volume, weigh less than 9.5 Ib/gal, and may be fresh or saltwater ba se. The typical low solids systems are flocculent, minimum solids muds, beneficiated clay muds, and low solids polymer muds. Most low solids drilling fluids are composed of water with varying quantities of bentonite and a polymer. The difference among low solids systems lies in the varying actions of different polymers. 

Theoretically, electrokinetic processes should also occur in nondisperse systems, but then additional factors arise (vortex formation in the liquid, settling of the particles, etc.) which produce a strong distortion. Hence, electrokinetic processes can be regarded as one of the aspects of the electrochemistry of disperse heterogeneous systems. 

In nondispersed systems no special agents are added to deflocculate the solids in the fluid. The main advantages of these systems are the higher viscosities and the higher yield point-to-plastics viscosity ratio. These alterated flow properties provide a better cleaning of the bore hole, allow a lower annular circulating rate, and minimize wash out of the bore hole. 

Our results indicate that x-ray fluorescence is highly useful for rapid and reasonably accurate analyses of whole coal for trace elements. Because of the speed and simplicity of the method, it is highly adaptable to large-scale surveys of coal resources. A suite of 24 samples can be analyzed for 21 elements in 3 days by manual instrumentation. While this simple procedure can not be used to determine certain elements, the time-saving factor over other methods (40 or 50 to 1 in the case of bromine by neutron activation) without loss of accuracy may well make x-ray fluorescence the method of choice for many elements. Improved equipment, such as nondispersive systems and automation, could extend the application of x-ray analysis to a dominant position for determining trace elements in whole coal. 

In a theoretical study of the advantages to be gained from nondispersive systems, Chester and Winefordner (28) have studied frequency-modulated sources in nondispersive atomic fluorescence, and have demonstrated a multiplex disadvantage for nondispersive atomic fluorescence systems. These studies have indicated that the limiting noise is flame background noise. 

To characterize a surface electrokinetically involves the measurement of one of the above electrokinetic effects. With disperse colloidal systems it is practical to measure the particle electrophoretic mobility (induced particle velocity per unit applied electric field strength). However, for a nondisperse system one must measure either an induced streaming potential or an electro-osmosis fluid flow about the surface. 

A nondispersive system of monochromation filters either the radiation or the electrical signal generated in the detector. In a dispersive monochromator, radiation is separated according to wavelength. The resolution of a monochromator is defined as where 8X is the minimum distance between the centers of two spectral lines which can just be dis-... 

Photomultiplier tubes have also been developed with response limited to the ultraviolet region (160 to 320 nm), the so-called solar-blind photomultipliers. They are helpful in reducing stray light effects from visible radiation and are useful as UV detectors in nondispersive systems. 

Nakahara, T., Tanaka, T., and Musha, S. (1978) Flameless atomic fluorescence spectrometry of mercury by dispersive and nondispersive systems in combination with cold-vapor technique. Bull. Chem. Soc. Jpn., 51, 2020-2024. 

In theory, no monochromator or lilter should be necessary for alomic fluorescence measurements when an LDI. or hollow-cathode lamp serves as the excitation source becau.se the emitted radiation is, in principle, that of a single element and will thus excite onlv atoms of that element. A nondispersive system then could be... 

Nondispersive IR systems are good for measuring concentrations of specific compounds under industrial and other similar circumstances. As can be readily understood, they are not generally used as research instruments and do not have scanning capabilities. However, they are robust and enduring and can be used for the continuous monitoring of specific compounds. Nondispersive systems are very common in NIR apph-cations, as discussed in Section 4.7. 

In industry, it is often necessary to monitor the quality of a product on a continuous basis to make certain the product meets its specifications. This online, real-time approach to analysis is called process analysis. IR spectroscopy is often the method of choice for process monitoring of organic chemical, polymer, and gas production. It is usually not feasible to use laboratory IR instruments under production conditions because they are too delicate, too big, and too expensive. Nondispersive systems have therefore been developed that are much sturdier and can be left running continuously. Many nondispersive systems have been designed for the NIR region. These will be discussed in Section 4.7. The mid-IR region is used mainly for monitoring gas streams. 

Figure 7.12 summarizes the transitions that occurred when TC was added to dispersed and nondispersed systems of MLO/water. In these emulsified particles, the confined W/O nanostructures were reversible structures, i.e., they existed in... 

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