Calcium, exchange with potassium

Frusemide (furosemide, Lasix) acts on the thick portion of the ascending limb of the loop of Henle (site 2) to produce the effects described above. Because more sodium is delivered to site 4, exchange with potassium leads to urinary potassium loss and hypokalaemia. Magnesium and calcium loss are increased by frusemide to about the same extent as sodium the effect on calcium is utilised in the emergency management of hypercalcaemia (see p. 740). 

Radenti et al. reported the corrosion rate of a typical potassium chloride fluid of 247 mils/year at 212°F. In contrast, they found by substituting potassium carbonate for potassium chloride, the corrosion rate was reduced to 3 mils/year t10 . Unfortunately, potassium carbonate is not optimum as a drilling fluid additive because it can produce massive amounts of calcium precipitation, may elevate the pH to undesirable levels, and in all cases reduces the calcium ion concentration to such a low level as to promote destabililzing cation exchange with clay minerals. 

Adsorption to the K+-covered siloxane surfaces of the clay, illite, can be estimated using Eq. 11-20. A tnt.eda is 300,000 L mol-1 and the surface area factor, /saf, for illite is 6 (Table 11.2). Since the ground water contains so much calcium relative to potassium (30 1), only a very small fraction of the cation exchange sites on the illite are covered with weakly hydrated potassium ions you assume/K+clay is about 0.01. Thus, you estimate ... 

Newly fermented wines are usually supersaturated with potassium bitartrate. Wineries routinely remove the excess potassium bitartrate in wines by refrigeration or ion exchange procedures. These steps are necessary to obtain a wine free of tartrate deposits after bottling. Calcium may also combine with tartrates which contribute to the deposits in wines. Generally, the stabilization practices for potassium bitartrate are sufficient to remove calcium tartrate from wines. 

The calcium uptake process appears to involve exchange with H+. Thus the ionophore nigericin, which catalyzes an H+/K+ exchange, inhibits uptake of calcium in the presence of potassium. 

For less activated aromatic systems (those without a nitro substituent), the halogen-exchange reaction has been investigated with potassium fluoride in a variety of polar aprotic solvents in the presence or absence of a catalyst (see Table 13). Many different types of catalysts have been investigated these include crown ethers.169 quaternary ammonium salts,163 164 phos-phonium salts,158167 aminophosphonium salts.162 compounds containing a phosphorus and an amino function,161 and inorganic fluorides of boron, aluminum, tin, phosphorus, titanium and zirconium.162 Different forms of potassium fluoride have been used these include spray-dried potassium fluoride,167 freeze-dried potassium fluoride,168 potassium fluoride recrystallized from methanol,165 and potassium fluoride dispersed oil calcium fluoride.166... 

Figure 1 shows the overall scheme for the preparation of a self-bound LSX adsorbent, from metakaolin pellets which after calcium exchange have Improved performance as adsorbents for air separation. We have made self-bound LSX by contacting the porous metakaolin pellet with a mixture of sodium and potassium hydroxides at relatively low temperatures and pressures. 

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