Hexametaphosphate, additive

Amphotericin B. Amphotericin B (3), an important polyene antibiotic, is administered almost exclusively via the intravenous route and is therefore discussed in more detail under the systemic antimycotics. The vaginal tablets contain 50 mg amphotericin B, and 100 mg tetracycline base per tablet (see also Antibiotics, tetracyclines). The tablets for oral use contain 50 mg amphotericin B, 250 mg tetracycline base, and 125 mg sodium hexametaphosphate. A combination ointment contains 1 mg fludrocortisone acetate, 2.5 mg neomycin, 0.25 mg gramicidin, and 1 g plastibase in addition to 30 mg amphotericin B (see also Antibiotics, peptides). 

Considerable laboratoiy work has indicated that the use of a dispersant such as sodium hexametaphosphate may assist in the stabihza-tion of the medium more recent data report the beneficial effect of the addition of polymers that reduce media viscosity while simultaneously producing a very low settling rate of the ferrous compound. This should be of great value for difficult separations, but at present no data are available from commercial operations. 

This is usually prepared by either a base-exchange method using sodium zeolite, by a lime-soda ash process, or by the addition of sodium hexametaphosphate. In addition to the bacteria derived from fhe mains water, additional flora of Bacillus spp. and Staphylococcus aureus may be introduced into systems which use brine for regeneration and from the chemical filter beds which, unless treated, can act as a reservoir for bacteria. 

Scale prevention methods include operating at low conversion and chemical pretreatment. Acid injection to convert COs to CO2 is commonly used, but cellulosic membranes require operation at pH 4 to 7 to prevent hydrolysis. Sulfuric acid is commonly used at a dosing of 0.24 mg/L while hydrochloric acid is to be avoided to minimize corrosion. Acid addition will precipitate aluminum hydroxide. Water softening upstream of the RO By using lime and sodium zeolites will precipitate calcium and magnesium hydroxides and entrap some silica. Antisealant compounds such as sodium hexametaphosphate, EDTA, and polymers are also commonly added to encapsulate potential precipitants. Oxidant addition precipitates metal oxides for particle removal (converting soluble ferrous Fe ions to insoluble ferric Fe ions). 

Phosphate. Addition of secondary Na or K phosphate (i.e. Na2HP04 or K2HP04) causes the precipitation of colloidal calcium phosphate, with concomitant decreases in the concentration of soluble calcium and calcium ion. Polyphosphates, e.g. Na-hexametaphosphate, chelate Ca2+ strongly and dissolve CCP. 

Foreign ions are masked with a composite EDTA-sodium hexametaphosphate reagent and interference by sulfide is overcome by the addition of mercuric chloride, which also mitigates interference by thiosulfate, sulfate, tetrathionate and iodide, and the precipitated mercuric sulfide is filtered off prior to the addition of chromogenic reagents and spectrophotometry. Beer s law is obeyed up to levels of 20 p,g nitrite in a 60 ml test solution. 

A polymeride of this salt, namely, Nickel Hexametaphosphate, [Ni(P03)2]s or NisP6Oia, is obtained as a green, gelatinous predpitate on addition of the corresponding sodium salt to a concentrated solution of nickel chloride.6... 

For example, sodium hexametaphosphate, which is also called Graham salts and which is a common food additive, generally has a chain length of 10 to 15 phosphorus atoms, not 6 phosphorus atoms as the name implies (26). 

The addition of phosphate — pyro-, tripoly-, and hexametaphosphate — also protects cooked meat from auto-oxidation. Ortophosphate gives no protection. The mechanism by which phosphates prevent autooxidation appears to be related to their ability to sequester metal ions, particularly ferrous iron, which is the major prooxidant (Pearson et al., 1977). The addition of NaCl increases retention of moisture in meat and meat products. 

Superior foaming properties of milk have been obtained by addition of calcium complexing agents. Kelly and Burgess (1978) demonstrated that addition of sodium hexametaphosphate to milk protein concentrate solutions prepared by ultrafiltration improved foam volume and stability on whipping. The addition of EDTA to milk, which causes dissociation of the casein micelle, improved the foaming properties of milk (Ward et al., 1997). 

The displacement effect of KCl In decreasing firmness of snap beans cooked earlier In distilled water can be seen In the bar chart of Figure 2. Bars not surmounted by the same letters were significantly different at the P<0.05 level. The soaklngs In the Indicated solutions were for 3 days at 1°C. Here the effect of CaCl addition In Increasing firmness Is also shown. Pods that had been softened by KCl had much of their firmness restored by a subsequent CaClp solution soak. The effect of Na hexametaphosphate was to decrease the firmness to about 25i of that for the ordinal canned beans. This material Is an effective chelator of Ca and Its use results In the solubilization of a large part of the pod pectin. 

Sodium hexametaphosphate (sometimes called Graham s salt) was first used in water treatment to introduce phosphate into boilers without producing precipitation in the feed lines. It was used in the preparation with 14 parts to 1 part of calcium and was essentially a softening process. Because of the mode of action and the extremely small amounts of the additive required, the technique was called "threshold treatment". An alternative name is sequestration. 

Sodium hexametaphosphate is one of a series of chain polymers termed polyphosphates, and threshold treatment using various members of the series has found extensive use in controlling calcium carbonate scale formation. Veale [1984] states that typically 5 mg/l of polyphosphate will inhibit the precipitation of 500 mg/l of CaCOy To control scale in sea water evaporation an additive mixture could include sodium tripolyphosphate, lignin sulphonates and an antifoaming agent. 

Grades ranged from 68 to 204 for the alcohol-precipitated pectinates, and from 92 to 244 for the comparable acid-alcohol-treated calcium pectinates. Trend curves in Figure 3 show that the calcium pectinates treated with acid-alcohol are superior in grade to the alcohol-precipitated products (17). The effect of the addition of calcium and sodium hexametaphosphate upon the grade of acid-alcohol-treated cal-... 

If solvent extraction is carried out in the presence of cyanide, the zinc group of metals (Zn, Cd, Hg) is complexed and they will not extract. Addition of citrate complexes the elements of the ammonia group (Fe, Al, etc.) so that their hydroxides will not precipitate. The precipitation of the alkaline earth phosphates can be prevented by the addition of hexametaphosphate (Jl). Under these conditions, Bi(III), TI(I), and Sn(II) interfere in alkaline solution. The bismuth can be removed by preextraction at pH 3. Alternatively, if a positive lead test is found, bismuth could be ruled out or confirmed by back-extracting at pH 3. If bismuth is present, it will remain in the organic layer while lead will go into the aqueous phase. Extraction of thallium can be prevented by extracting the lead at pH 6.0-6.4 with chloroform. Or the thallium can be back-extracted at this pH this requires much closer control of the pH. The oxidation of dithizone by air is catalyzed by the presence of significant amounts of manganese (II). 

The reverse microemulsions were prepared by dissolving AOT in isooctane and injecting aqueous solutions in the reverse micellar solutions. The distilled water used was prefiltered and any dissolved oxygen was purged by bubbling of argon. It was shown that stable PbS could be synthesized easily up to w = 4, but at higher values, e.g. w = 10, the particles required stabilization by the addition of sodium hexametaphosphate. The particle size was 2-4 nm. 

With a high acid concentration in the electrolyte, thermal precipitation of VOj can be prevented because VOj is stable due to the dimerization of VOj irais to V204 and 203" " species. However, with an increased acid concentration, the solubility of V(II)W(III) species decreases, but the viscosity increases obviously. This means that more energy is consumed to pump the electrolyte into the battery. The concentration of acid should be in the range of 2-4 M. Recently, to increase electrochemical activity and the concentration of vanadium ions in the electrolyte, various organic additives, such as sodium hexametaphosphate, alkali metal sulfate, and alkali metal oxalate, have been investigated and added into the RFBs electrolytes [21, 22]. 

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