Water - Phosphoric Acid

As discussed in Chapter VI, the equilibria in a water-phosphoric acid solution have been studied by numerous authors resulting in nine suggested reactions to explain the system behavior  

Although there has been much study of this system and a large body of good experimental data has been published, the inclusion of all nine equilibria in a mathematical model would be unwarranted since it is unlikely that all species are actually present at the same time. There is as yet insufficient knowledge of the species present in the solution. The investigator must choose a subset of the equilibria. 

In 1976, Pitzer and Silvester (18) published the result of their study of modeling the phosphoric acid-water system using the Pitzer equations for activity and osmotic coefficients. As discussed in Chapter IV, Pitzer found the following equation for the activity coefficient of ion i by taking the appropriate derivative of his definition of the excess Gibbs free energy  

For the long-range electrostatic effects, the following correlatlona were chosen  

The virial coefficients for a binary strong electrolyte solution were lumped together and assigned an empirical equation to show the ionic strength dependence  

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Mineral acids are used as catalysts, usually in a concentration of 20— 40 wt % and temperatures of 30—60°C. An efficient surfactant, preferably one that is soluble in the acid-phase upon completion of the reaction, is needed to emulsify the a-pinene and acid. The surfactant can then be recycled with the acid. Phosphoric acid is the acid commonly used in the pine oil process. Its mild corrosion characteristics and its moderate strength make it more manageable, especially because the acid concentration is constandy changing in the process by the consumption of water. Phosphoric acid is also mild enough to prevent any significant dehydration of the alcohols formed in the process. Optimization of a process usually involves considerations of acid type and concentration, temperature, surfactant type and amount, and reaction time. The optimum process usually gives a maximum of alcohols with the minimum amount of hydrocarbons and cineoles. 

Dhouib-Sahnoun, R., Feki, M., and Ayedi, H.F. Liqtrid-liquideqtrilibriaof the ternary system water + phosphoric acid + tributyl phosphate at 298.15 K and 323.15 K, J. Chem. Eng. Data, 47(4) 861-866, 2002. 

Carothers WW, Adami LH, Rosenbauer RJ (1988) Experimental oxygen isotope fractionation between siderite-water phosphoric acid liberated C02-siderite. Geochim Cosmochim Acta 52 2445-2450... 

Deionized Water Phosphoric Acid (B5%) Citric Acid (50%) Nitric Acid (70%) Avanel S-70... 

BHT, BHA, TBHQ Fats, oils extraction from hexane solution with acetonitrile LiChrosorb RP-18 Acetonitrile/water-phosphoric acid, gradient elution UV 280 nm 139... 

Mobile phase Gradient elution dependent on column e.g., elute iso-a-acids with methanol water phosphoric acid (75 24 1 v/v/v), then increase proportion of methanol Water ion pair methanol acetonitrile THF (320 9.9 580 40 50 v/v/v/v/v) Methanol water + ion pair b (725 275 v/v) or methanol water + ion pairb (780 220 v/v) Methanol water phosphoric acid 0.1 M EDTA (aq) (812 184 2.5 1 v/v/v/v)... 

Methanol/water/ phosphoric acid 100 X 8-mm-ID NovaPak C18 5-/on cartridge under radial compression No Ambient 313 28... 

Methanol/water/ phosphoric acid 250 X 4.5-mm-ID Alltech 10-jU.m 600RP No 40 334 29... 

Acetonitrile/water/ phosphoric acid gradient 250 X 4-mm-ID 5-/xm Grom-Sil ODS-O AB Partial Ambient 314 31... 

Methanol/water/ phosphoric acid Zorbax SB C8 No Ambient MS detector 32... 

The phosphorus leaves the furnace as a vapor and is condensed by direct contact with water. Phosphoric acid of high purity is made by burning phosphorus with air and hydrating the resulting P205 with water, according to the reaction ... 

Chloramphenicol, the 1- and 3-diacetoxy derivatives, and 1,3-diacetoxychloramphenicol were separated by chromatography on a Spherisorb 5 ODS column (5 mm X 250 mm, 5 /xm). The mobile phase was composed of ethyl acetate-methanol-distilled water-phosphoric acid (6.0 41 52 5 0.5, v/v/v/v). The effluent was monitored at 278 nm. Enzyme activity was based on the formation of the monoacetoxy derivatives. 

Solvent A 0.1 M KH2PHO4 in water + phosphoric acid, Solvent B ... 

When tetraphosphorus decoxide dissolves in water, phosphoric acid (H3PO4), also called orthophosphoric acid, is produced ... 

The faster ductile failure in water/phosphoric acid solution is thought to be due to swelling, and thus making it a physical (ESC) process. The failure times in water and phosphoric acid solution are comparable. Apparently, the physical factor is the same in both water and phosphoric acid solution, as already indicated by the similar saturation times and degradation times (Fig. 1). 

Sugar Syrup 72.7% w/w Sodium Benzoate Solution 23.5% i. Water Phosphoric Acid 85%... 

SI Column uBondapak C18 (300x3.9 mm I.D.), S2 column, Partlsll 10 ODS-3 (250x4.6 mm I.D.) both with mobile phase 0.02 M methanesulfonlc acid 1n acetonitrile - water - phosphoric acid 12 87 1)(pH-2.2 with 2 M sodium hydroxide), flow rate 3.0 ml/min. 

Mobile phase MeCN MeOH water phosphoric acid KH2PO4 octanesulfonic acid 50 150 900 0.25 0.75 0.05 (v/v/v/v/w/w)... 

Mobile phase MeOH water phosphoric acid sodium 1-hexanesulfonate 24 76 0.03 0.094 Flowrate 2 Injection volume 20 Detector UV 220... 

Mobile phase MeOH water phosphoric acid 75 25 0.1... 

Mobile phase MeCN water phosphoric acid 50 50 0.2... 

Column 250 X 4.6 5 )i.m Phenomenex < ano-bonded silica Mobile phase MeCN water phosphoric acid 400 600 1 Flowrate 1.5 Detector UV 225... 

Mobile phase Gradient. A was MeCN water phosphoric acid 240 1650 27, adjust pH to... 

In the separate, or hydrated state, P,0, 3HO, or P,0, H,. This acid is formed when phosphurets of the alkaline metals act on water, or when phosphorus is boiled with alkalies and water, phosphoric acid and phosphuretted hydrogen gas being formed at tne same time. The two acids combine with the base and if this be lime or baryta, the hypophosphite being soluble, is easily separated from the insoluble phosphate. From the hypophosphite of baryta sulphuric acid removes the baryta, and the hypophosphorous acid is left, dissolved in water. By gentle evaporation it may be obtained as a deliquescent crystalline mass, which is the hydrated acid. 

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