Potassium phosphate

Potassium phosphates are excellent fertilizers, and their very high analysas is an advantage that has stimulated much research in an effort to find an economical production process. However, no process has been developed that is economical enoi Qh to result in w e-spread production therefore, present use is linuted to special purposes for which the h h cost can be justified. 

At present, most of the potasaum phosphates used in fertiDzers are produced from potassium hydroxide or carbonate and phosphoric add and are used in liquids for foliar application or other specialty uses. 

Some of the alternative salts of potassium phosphates are given in Table 14.7. 

In addition, a potassium pdyphosphate solution of 0-26-27 grade has been produced from superphosphoric acid and potassium hydroxide it contains a mixture of ortho, pyro, and higher polyphosphates. 

and others have produced potassium meta-phosphate in pilot plants by higtHemperature reaction of KQ and phosphoric acid. The pure material, KPO3, has a grade of about 0-60-40 and, thus, a 100% nutrient content (on an oxide basis). 

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A first approach to testing, ASTM D 1094, is to create, using a potassium phosphate reagent, a separation between two layers, hydrocarbon and aqueous. The degree of separation of the two phases is estimated by attributing a grade from 1 to 3 and the appearance of the interface by five levels of observation 1, lb, 2, 3, and 4. The specifications establish both the quality of separation (2 is the maximum) and the appearance of the interface (lb maximum). 

D-Methyl mannoside with 2 M KSCN at pH 7.5 in potassium phosphate buffer... 

Potassium Phosphates. The K2O—P20 —H2O system parallels the sodium system in many respects. In addition to the three simple phosphate salts obtained by successive replacement of the protons of phosphoric acid by potassium ions, the system contains a number of crystalline hydrates and double salts (Table 7). Monopotassium phosphate (MKP), known only as the anhydrous salt, is the least soluble of the potassium orthophosphates. Monopotassium phosphate has been studied extensively owing to its piezoelectric and ferroelectric properties (see Ferroelectrics). At ordinary temperatures, KH2PO4 is so far above its Curie point as to give piezoelectric effects in which the emf is proportional to the distorting force. There is virtually no hysteresis. 

Potassium Phosphates. Potassium phosphate salts are analogous to the sodium salts and share many of the same functional properties. The higher cost of potassium hydroxide has restricted these salts to appHcations where high solubiUty or nutrient value is important. Potassium salts are manufactured like their sodium analogues, often on the same equipment. Many of the potassium phosphates are more deflquescent than their sodium analogues and may require special storage and moistureproof containers. 

Anhydrous monocalcium phosphate, Ca(H2PObe made in a pan mixer from concentrated phosphoric acid and lime. The high heat of reaction furnishes essentially all the necessary thermal input and subsequent drying is minimized. A small amount of aluminum phosphate or a mixture of sodium and potassium phosphates is added in the form of proprietary stabilizers for coating the particles. Heat treatment converts the coating to a protective polyphosphate (19). 

U.S. consumption of industrial-grade phosphoric acid and phosphates in 1993 according to product categories (34) was phosphoric acid, at 29% sodium phosphate, 52% calcium phosphate, 7% potassium phosphate, 3% ammonium phosphate, 5% and others, 4%. Consumption according to market is given in Table 12. 

Precipitator dust often contains concentrated amounts of minor ore components that make it attractive. The potassium, phosphate, and 2inc content have resulted in its use in ferti1i2er, and the sdver and gallium content have been the subject of some recovery efforts (see Recycling). 

Devising an economical method of producing agricultural-grade potassium phosphates from potassium chloride and wet-process phosphoric acid has been the subject of intense agricultural—chemical research (37—39). Limited quantities have been produced industrially. The impact on the overall quantities of phosphoms and potassium compounds consumed by the fertilizer industry is small. Because potassium phosphates are an excellent source of two essential fertilizer elements, this research is expected to continue. 

Condensed potassium phosphates have been used as builders in Hquid detergents. The compound tetrapotassium pyrophosphate [7320-34-5] which forms by dehydrating K HPO at 400°C, was used. 

Nutrients are usuaUy added at concentrations ranging from 0.005 to 0.02% by weight (16). In a field appHcation using hydrogen peroxide, nutrients were added to the injected water at the foUowing concentrations 380 mg/L ammonium chloride 190 mg/L disodium phosphate, and 190 mg/L potassium phosphate, the latter used primarily to complex with iron in the formation to prevent decomposition of hydrogen peroxide (24). 

A striking example of the importance of narrowing the focus in research, which is what the concept of the parepisteme really implies, is the episode (retailed in Chapter 3, Section 3.1.1) of Eilhard Mitscherlich s research, in 1818, on the crystal forms of potassium phosphate and potassium arsenate, which led him, quite unexpectedly, to the discovery of isomorphism in crystal species and that, in turn, provided heavyweight evidence in favour of the then disputed atomic hypothesis. As so often happens, the general insight comes from the highly specific observation. 

Other regenerative methods are occasionally used to remove HjS from hydrocarbons, such as the tri- potassium phosphate (TPP) process. Other installations are DEA or ME A, and most TPP units have been converted to DEA since the latter consumes less steam for regeneration. 

The ionic species of the mobile phase will also affect the separation. This is shown in Table 4.3 by the difference in resolution values for magnesium chloride buffer compared to sodium sulfate buffer. In addition, calibration curves for proteins in potassium phosphate buffers are shallower than those generated in sodium phosphate buffers. The slope of the curve in Sorenson buffer (containing both Na and ) is midway between the slopes generated with either cation alone (1). Table 4.4 illustrates the impact of different buffer conditions on mass recovery for six sample proteins. In this case, the mass recovery of proteins (1,4) is higher with sodium or potassium phosphate buffers (pH 6.9) than with Tris-HCl buffers (pH 7.8). 

FIGURE 8.7 Effect of pH on retention of amino acids. Column and flow rate Same as Fig. 8.1. Mobile phase 10 mA1 potassium phosphate with SO mM HFIP pH as indicated (adjusted prior to the addition of HFIP). 

FIGURE 10.2 Calibration curves for proteins on SynChropak GPC columns. Mobile phase 0.1 M potassium phosphate, pH 7. (From MICRA Scientific, Inc., with permission.)... 

Each SynChropak column is tested chromatographically to assure that it has been packed according to specifications. For SynChropak GPC columns, a mixture of a high molecular weight DNA and glycyltyrosine, a dipeptide, is used to evaluate internal volume and efficiency. The mobile phase used for the test is 0.1 M potassium phosphate, pH 7, and the flow rate is 0.5 ml/min for 4.6-mm i.d. columns. Minimum plate count values and operational flow rates are listed in Table 10.4 for 4.6-mm i.d. columns of all supports and the various diameters of the SynChropak GPC 100 columns. 

An amount of enzyme preparation equivalent to 900 mg of wet cells was made up to 25 ml with the above potassium phosphate buffer solution. 150 mg (1.15 mmol) of 5-fluorouracil and 1.0 gram of thymidine (4.12 mmol) were dissolved in 15 ml of the above potassium phosphate buffer solution. The mixture was incubated at 37°C for 18 hours. After this time, enzyme action was stopped by the addition of four volumes of acetone and one volume of peroxide-free diethyl ether. The precipitated solids were removed by filtration, and the filtrate was evaporated under nitrogen at reduced pressure until substantially all volatile organic solvent had been removed. About 20 ml of aqueous solution, essentially free of organic solvent, remained. This solution was diluted to 100 ml with distilled water. 

Fig. 6-7. Asymmetry factor (AJ of the L-enantiomer versus sample load (A) and versus flow rate (B) on L-PA-imprinted polymers. Flow rate 1.0 ml min . Mobile phase MeCN/[potassium phosphate 0.05 M, pH 7] (7/3, v/v).

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