Magnesium salt concentrations, effect

Addition of a salt can transform the shale by cation exchange to a less sensitive form of clay, or reduce the osmotic swelling effect by reducing the water activity in the mud below that which occurs in the shale. These effects depend on the salt concentration and the nature of the cation. Salts containing sodium, potassium, calcium, magnesium, and ammonium ions ate used to varying degrees. 

Magnesium salts exhibit properties similar to those of calcium, except that they generally are slightly more soluble and normally are present in MU water sources at a lower level of concentration, so that the overall scaling and deposition effect of magnesium salts is lessened. 

Table I summarizes the effect of such nitrates on the azeotropic composition in the nitric acid-water system. Addition of potassium nitrate increases the azeotropic composition, but other nitrates decrease it, the amount by which the azeotrope is displaced being proportional to the amount of nitrate added. The azeotrope is eliminated completely at salt concentrations of 45, 48, 54, or 64% by weight for addition of magnesium, zinc, lithium, or calcium nitrates respectively.

For the study of magnesium ion (Mg2+) effects on the system performance of the limestone DA process, Epsom salt (MgS04 5H20) was added to adjust the Mg2+ concentration in the scrubbing liquor. The base case system performance was established without the addition of epsom salt the steady-state concentration of Mg2+ was 355 Dpm. In subsequent tests, all operating conditions -- except for Mg2 ... 

As the reaction progresses, the concentration of the ammonium ions, due to the dissociation of the completely ionized ammonium salt, increases and consequently the concentration of the hydroxyl ions decreases owing to the common-ion effect (cf. Section 1.27). The small hydroxyl-ion concentration, already low, is decreased still further so that much of the magnesium salt remains in solution. In the presence of a sufficient concentration of ammonium salts, the hydroxyl-ion concentration is reduced to such an extent that the solubility product of Mg(OH)2 is not exceeded (cf. Section 1.28) hence magnesium is not precipitated by ammonia solution in the presence of ammonium chloride or other ammonium salts. 

The type and concentration of the acid(s) can have a marked effect on the neutralisation process, largely owing to the solubility of the reaction product(s). The acids most commonly found in waste water are nitric (HNO3), hydrochloric (HCl), sulfuric (H2SO4), hydrofluoric (HF) and phosphoric (H3PO4). The solubilities of their calcium and magnesium salts are summarised in Table 28.6 [28.7] (N.B., all sodium salts are soluble). 

Figure 12 outlines the effect of salt concentration, in this case magnesium, on gel strength and gel point of a a typical purified deacetylated PS-60 sample. Solutions were prepared at 95 C in deionized water containing various various concentrations of magnesium chloride using 0.5% gum. The viscosity of the samples was monitored upon cooling an apparent increase was... 

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