Ionic impurities, contamination from

Apart from halide and protic impurities, ionic liquids can also be contaminated with other ionic impurities from the metathesis reaction. This is especially likely if the alkali salt used in the metathesis reaction shows significant solubility in the... 

The simplest estimate of the overall salinity of water (its ionic impurity content) is obtained by measuring its conductivity. Such measurements can be useful, for instance, when checking the purity of rinsing waters from the plating and metalfinishing industries. A quantitative estimate of the degree of contamination is possible via conductometry when the qualitative composition of the ionic contaminants is known and does not change. 

Abdul-Sada, A. K. Avent, A. G. Parkington, M. J. et al. The removal of oxide impurities fi om room-temperature halogenoaluminate ionic bquids, J. Chem. Soc., Chem. Commun., 1987, 1643-1644 Abdul-Sada, A. K. Avent, A. G. Parkington, M. J. et al. Removal of oxide contamination from ambient-temperature chloroaluminate(III) ionic bquids, J. Chem. Soc., Dalton Trans., 1993, 3283-3286. 

Ion milling is a more widely applicable etching technique in that all materials may be sputtered away anisotropically. The ion milling rate typically does not vary more than a factor of 100. Redeposition of material from the substrate or surrounding fixtures can lead to undesirable cross-contamination. Hosaka et al. (39) used SIMS to show that redeposition of ionic impurities can occur during ion etching of SiO layers on Si when using a... 

Apart from halide and protic impurities, ionic liquids can also be contaminated with other ionic impurities from the metathesis reaction. This is especially likely if the alkali salt that is used in the metathesis reaction shows significant solubility in the ionic liquid formed. In this case the ionic liquid can contain significant amounts of the alkali salt. While this may not be a problem even for some catalytic applications (since the presence of the alkali cation may not effect the catalytic cycle of a transition metal catalyst) it is of great relevance for the physicochemical properties of the ionic liquid. 

The hypothetical polarization curve shown in Figure 5.2 illustrates a near-realistic industrial condition since most corroding solutions contain more than one oxidizing agent. Normally, ferric-ferrous salts and other ionic impurities are contained in acid solutions due to contamination from corrosion products and existing oxidizers [4]. Nevertheless, the electrochemical situation shown in Figure 5.2 implies that... 

Ionic impurities can be selectively removed from contaminated chromic acid (Fig. 7.18(b)). 

The model expressed by Eq, 11 is used to project the time-to-failure from test to field conditions, making use of the failure acceleration due to relative humidity, temperature, and electric field. The model has been verified experimentally and has been consistent. The values of B, m, and A HpWillvarywith contaminants, material and surface condition. The ionic impurity environment is assumed notto vary among all samples under test within the same experiment. The metallic ion concentration will vary with the samples contamination due to process residues and other ionic species that may be present in the system. Adding chemicals to enhance the oxidation/reduction process, therefore the electrodeposition, is another way to accelerate the formation of dendrites, however, itwould be difficult to relate the results to field conditions if a new mechanism is introduced. 

Problems are sometimes encountered in contamination of the DNA with acrylamide monomers or other impurities from the gel matrix. Such contamination is usually apparent from the formation of an excessive turbidity during the ethanol-precipitation step. Pure DNA preparations in the microgram amounts eluted rarely give visible turbidity. A convenient purification procedure is to absorb the DNA onto a small (1 ml) column of DEAE-cellulose (DE-52, Whatman) in a low ionic strength buffer. Non-ionic im-... 

Thus the condensation methods of formation of colloidal solutions, mainly from true ionic or molecular solutions, are most important in nature. The sols obtained nearly always are contaminated by various impurities, usually electrolytes, including components of the original true solutions. 

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