Solubility aluminum phosphate

Sodium alumiaate is an effective precipitant for soluble phosphate ia sewage and is especially useful ia wastewater having low alkaliaity (20,21). Sodium alumiaate hydrolyzes ia water to Al(OH)2 and Al" which precipitate soluble phosphate as aluminum phosphate [7784-30-7], AlPO. Sodium alumiaate has also been described as an effective aid for the removal of fluorides from some iadustrial waste waters (22). Combiaations of sodium alumiaate and other chemicals are being used to improve the detackification of paint particles ia water from spray-painting operations (23). 

Inorganic reactions in the soil interstitial waters also influence dissolved P concentrations. These reactions include the dissolution or precipitation of P-containing minerals or the adsorption and desorption of P onto and from mineral surfaces. As discussed above, the inorganic reactivity of phosphate is strongly dependent on pH. In alkaline systems, apatite solubility should limit groundwater phosphate whereas in acidic soils, aluminum phosphates should dominate. Adsorption of phosphate onto mineral surfaces, such as iron or aluminum oxyhydroxides and clays, is favored by low solution pH and may influence soil interstitial water concentrations. Phosphorus will be exchanged between organic materials, soil inter-... 

Suspension of water soluble solids in oil can be achieved by a variety of chemical additives. Chemical suspension additives that have been suggested include alkyl mercaptophosphonic acids(174), organophylic clay plus hydroxypropyl cellulose(175), polyols(176), aluminum stearate(177), organophylic clay plus surfactant(178-181), aluminum phosphate esters(182), and acrylate copolymers(183-184). 

B (a) Possible products are sodium chloride, NaCl, which is soluble, and aluminum phosphate, A1P04, which is insoluble. The net ionic equation is ... 

If catalysts are prepared by coprecipitation, the composition of the solutions determine the composition of the final product. Often the composition of the precipitate will reflect the solution concentrations, as was shown for CuO/ZnO catalysts for methanol synthesis [18], but this is not necessarily the case. For al-minum phosphates it was found that at low P A1 ratios the precipitate composition is identical to the solution composition, but if the P A1 ratio in the solution comes close to and exceeds unity, the precipitate composition asymptotically approaches a P A1 ratio of 1 [19]. Deviations from solution composition in coprecipitation processes will generally occur if solubilities of the different compounds differ strongly and precipitation is not complete or, if in addition to stoichiometric compounds, only one component forms an insoluble precipitate this the case for the aluminum phosphate. 

The small Al3+ cation with a high charge does not exist in the free form under physiological conditions. In mildly acid intracellular conditions, aluminum is bound to phosphate. Aluminum forms soluble salts with some acids, for example, with citric acid [82], or complexes with some compounds, for... 

At present, only two aluminum phosphate ores are known to be used for direct application after thermal treatment. One such ore is found near Thies, in Senegal. The as-mined ore contains about 29 percent P205 on a dry basis after calcination it contains over 34 percent P205. The calcined product is ground to about 95 percent smaller than 0.15 mm and marketed for direct application under the trade name Phosphal. About 75 percent of the P205 is soluble in alkaline ammonium citrate, and the product is effective as superphosphate in calcareous, neutral, and acid... 

Sodium Aluminum Phosphate, Acidic, occurs as a white powder. It is anhydrous or contains two or four molecules of water of hydration. It is insoluble in water, but is soluble in hydrochloric acid. 

Deep and geothermal wells are inherently hot and are well served by aluminum phosphate formulations (see Chapter 11). The dynamic temperature in these wells is 250 °F (121°C) or higher, and the static temperature is >350 °F (235°C). For these wells, berlinite-based CBPC works well with its maximum solubility at 244 °F (118°C) of alumina and phosphoric acid solution. As we have seen in Chapter 11, this reaction takes place at 302 °F (150°C) that is in the range of the temperatures of deep and geothermal wells [7]. Even at these temperatures, the solubility of aluminum oxide is too low, but addition of a small amount of microcrystalhne or amorphous aluminum hydroxide aids in increasing the soluble ions in the solution. With its large surface area, alumina provides the necessary solubility at the given downhole temperamre. 

The commonly recognized adjuvants are remarkable for their diversities. Soluble immunogens can be adsorbed onto the following kinds of inorganic suspensions alumina cream, aluminum phosphate, and aluminum sulfate. Adsorption onto organic carriers such as blood, charcoal, calcium alginate, or polyacrylamide gels has also enhanced responses. A Maalox... 

Figure 9.6 explains the observations that (1) phosphate is fixed in large amounts as iron and aluminum phosphates in acid soils, where Fe3+ and Al3+ activities are high (2) calcium fixes phosphate similarly in basic soils, where Ca2+ activity is high and (3) maximum amounts of phosphate are available at slightly acid to neutral pH where the solubilities of Fe, Al, and Ca phosphates are highest simultaneously... 

The nonlabile fraction of inorganic phosphorus not available to plants is sometimes divided into the occluded and reductant soluble forms. Occluded phosphorus consists of aluminum- and/or iron-bonded phosphates surrounded by an inert coat of another material such as oxides or hydrous oxides of iron or aluminum. Reductant soluble forms are covered by a coat that may be partially or totally dissolved under anaerobic conditions (Uehara and Gillman, 1981). The opportunities for occlusions to occur increase dramatically with soil age (Walker and Syers, 1976). This is because substantial amounts of Fe and Al oxides tend to be present only in heavily weathered soils in which the secondary silicate minerals have already dissolved (Fox et al., 1991). Data from tropical forest chronosequence studies in Hawaii are more or less in accordance with this view the fraction of P present in the occluded form increases with soil age (Crews et al, 1995). Nevertheless, that study also showed high amounts of nonoc-cluded (i.e., labile and accessible) inorganic phosphorus to be present, even in forests growing on the oldest soils. 

Under oxidized conditions in mineral wetland soils, the coating of hydrated ferric oxides on silt or clay particles have occluded in them several forms of phosphate including ferric phosphate, aluminum phosphate, and calcium phosphate (Figure 9.32). As a result of anaerobic conditions, reduction of hydrated ferric oxide to more soluble ferrous hydroxide results in the release of these occluded phosphates. Calcium phosphate released in this manner is available to wetland plants, whereas the occluded ferric phosphate is probably not available to the plants until it has been reduced to more soluble ferrous phosphate. 

Iron and aluminum oxides present no special problem within the range of occurrence in commercial phosphate rocks these oxides usually are dissolved in nitric acid and reprecipitated during ammoniation as citrate-soluble phosphates, TVA tested leached-zone" Florida phosphate containing a high percentage of aluminum phosphate minerals in a special nitrophosphate process... 

It is composed almost completely of iron and aluminum phosphates (mostly crandallite, Ca (Fe, Alls (POsla (0I 5 3H20, and miOisite Ca (Na,K) (Fe, AQe (POs)2 (0I 5 3H20) and is altogether unsuitable for conventional phosphoric acid/soluble phosphates production. All the accessible reserves of phosphate rocks on Christmas Island have been signibcantly depleted and will suffice for 16 to 17 years at most. 

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