Neutral salt content

The effect of pH is complex. Starting with strongly acid (low pH) systems, gel times initially decrease rapidly as the OH concentration is increased, then pass through a minimum and finally increase rapidly as the pH continues to increase. For all types of gels, the effect salts in decreasing gel times is much more pronounced on the basic side than on the acid side, and the location of the minimum in the gel time versus pH curve is a very sensitive function of the neutral salt content and even of the specific salt employed. 

Table 8 Comparison of the material consumption rates and iron uptake rates for low and high neutral salt contents as a function of the running time as well as the percentage iron uptake rate, referring to the material consumption rate [19]...

It should also be noted that no influence of the neutral salt content was found in these experiments. 

Das Korrosionsverhalten von verzinkten und unlegierten Stahlrohren in Trinkwassern mit unterschiedlicher Harte und erhohtem Neutralsalzgehalt (Corrosion of galvanised and unalloyed steel tubes in drinking water of different hardness and increased neutral salt content) (in German)... 

Chlorination of thick lime slurry at 40—45°C forms large crystals of hemibasic calcium hypochlorite. The fine crystals obtained under 30°C are difficult to filter and since they invariably contain occluded mother Hquor, they have frequently been incorrectly referred to as monobasic or two-thirds basic (187,188). The isolated hemibasic crystals are suspended in a thin chlorinated lime slurry and chlorinated, producing laminar crystals of Ca(OCl)2 2H20, which are filtered and dried. Mother Hquors are treated with a lime slurry to recover the dibasic crystals, which are then suspended in a Hquor of lower CaCl2 content and chlorinated to form the neutral salt (188—190). 

Fig. 37. Dependence of the thermodynamic parameters AH and AS of triple-helix formation on the imino acid content of the peptides (obtained by cleavage of calf skin-type I collagene with cyanogene and subequent isolation by column chromatrography)3) and of the native neutral salt-soluble skin collagene of various animals. The entropy values are denoted by dotted lines...

A number of investigations concerning the effect of added electrolytes and change in the solvent polarity have been reported (see ref. 25 pp. 17-19 for a more detailed account). The addition of neutral salts causes a large increase in the rate of reaction in both the one and two-proton mechanisms. In addition, the effect of increasing the water content in a dioxan-water solvent, provided that the concentration of water is above a certain threshold value, also produces a large increase in... 

The XRD patterns of alkaline or ammonium salts of H3PW12O40 or H4SiWi2O40 were typical of the cubic structure. No additionnal XRD peak was observed indicating the absence of other phases. The same unit cell was measured for the different Cs salts of H3PW12O40 (ao = 1.184 nm) and for the Cs salt of H4SiWi204o ( ag = 1.178 nm), in agreement with the value reported in the literature for the neutral salts [9,11] whatever be the Cs content. 

Montmorillonite, one of the most commonly encountered smectites, is similar to pyrophyllite (2 1) but has some interlayer cations and extra water. In pyrophyllite the layers are neutral because Si " in the tetrahedral sheet is not replaced by Al. In the smectites there is substitution of Al for Si " in the tetrahedral sheets, and occasionally Al appears in octahedral locations as well (for the names assigned to the end members, see Brindley and Brown, 1980, pp. 169-170.) The charge imbalances of the substitutions are compensated by interlayer cations, usually Na or Ca. These cations are easily exchangeable. The hydration level of the smectites is also variable. These minerals are very responsive to changes in water content as well as to the salt contents of the water. Other liquids that might be associated with the minerals and temperature can also effect changes in the chemical and crystal structure. 

Based on a study comparing N-Viro soil physical properties with those of mineral soils, the physical characteristics of N-Viro soils suggest that chemical characteristics (such as high initial pH, acid neutralizing capacity, and high soluble salt content), rather than physical attributes, are likely to limit the use of these materials as soil substitutes. 

The sample matrix may also be modified to enhance extraction recovery. This is typically done by either dissolving a solid sample in a suitable solvent, usually water or a strongly aqueous mixture, or by modifying the pH or salt content of a solution. Modifying the pH to change the extraction behavior works the same way in SPME as it does for classical liquid-liquid extraction. At low pH, acidic compounds will be in the neutral form and will be extracted preferentially into the fiber coating at high pH, basic compounds are extracted favorably. Neutral compounds are not affected appreciably by solution pH. 

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