Phosphoric acid extractant

Phorex [Phosphoric acid extraction] A process for purifying phosphoric acid by solvent extraction with -butyl or n-amyl alcohol. Developed by Azote et Produits Chimiques, France. 

Lanthanides are also found as minor components in other ores, particularly in association with uranium or in phosphate rock. These are often coextracted with the major product and can be economically recovered from the waste streams resulting from the uranium or phosphoric acid extraction. 

The mechanism of U02 " extraction by monoalkyl phosphoric acid reagents appears to be a more complex process than for their dialkyl counterparts. This results from the polymerization of the monoalkyl phosphate in the organic phase and the hydration of the extracted uranyl species so that variable stoichiometries arise for the extractant/water/UO complex. The extraction of from sulfuric acid by mono-2,6,8-trimethylnonyl phosphoric acid (H2DDP) and mono-n-butyl phosphoric acid (H2MBP) as 0.05 M solutions in benzene was shown to follow equations (61) and (62) when an excess of extractant was present. When an excess of uranium was present, equations (63) and (64) applied where n, x, y and z were variable numbers which depended upon the extent of extractant polymerization and hydration of the extracted species. Synergistic effects may also be found with the monoalkyl phosphoric acid extractants and in one recent example the use of tri-n-octylphosphine ocxide (TOPO) as a synergist with H2MEHP allowed the extraction of U02 from phosphoric acid solutions. The uranium may be returned to the aqueous phase by contact with concentrated acid, which reverses the extraction process by protonation of the phosphate. 

Sample preparation 1 mL Plasma + doxepin + NaOH + hexane isoamyl alcohol 98 2, extract. Remove the organic phase and add it to 0.03% phosphoric acid, extract, iiyect an aliquot of the aqueous phase. 

Sample preparation Homogenize liver at 20 mg/mL in 50 mM pH 7.4 TWs-HCl buffer. 200 (xL Plasma or 250 p.L liver homogenate + 250 ng IS -i- pH 7.3 ammonium phosphate buffer -I- MTBE, extract. Remove the organic layer and add it to 250 xL 50 mM phosphoric acid, extract. Remove the aqueous layer and add it to 100 pL MeCN, inject an aliquot. 

Figure 19 presents the curves for phosphoric acid distribution between water (pure solution) and extractants comprising a quaternary amine and a sulfonic acid. The extraction is proportional to the concentration of the active components and decreases slightly on elevation of the temperature. The distribution curves show that these extractants, found suitable for sulfuric acid extraction, are not sufficiently basic for the extraction of HsPO i, which is a much weaker acid (free acid concentrations of about 6 M are required to reach loading of 1 mole of acid per mole of amine). An extractant comprising a long-chain tertiary amine (trilauryl amine, TLA, Alamine 304, produced by Henkel) and a-bromolauric acid (ABL, Miles Yeda) was tested. The distribution curves for phosphoric acid extraction from pure solutions are shown in Fig. 20. The extraction is proportional to the concentration of the active components and depends on the temperature. Note that whereas the extraction decreases on elevation of the temperature at the lower concentration range, it increases with temperature at concentration ranges at which the H PO /amine molar ratio is greater than one. Similar reverses in the effects of various parameters at about stoichiometric extraction were noted in the past. They are explained by shifting from the ion-pair formation mechanism to the H-bonding one [58,59].

There are two apparent artifacts in this correlation. First, one would not expect based on these arguments that the acidic phosphoric acid esters HDOP, HDBP, and HDEH P (bars U, V, and W) would demonstrate as great a selectivity for europium as is observed. Similarly, there is no apparent reason for the enhanced selectivity demonstrated by 100% TBP for americium for extraction from 13 M HNOj (bar G). In the case of the phosphoric-acid extractants, the apparent anomaly is a manifestation of the steep slope of the linear relationship between distribution ratios and atomic number (cation radii) as shown in figs. 4 and 5, and a mismatch of the ionic radii of americium and europium. It is generally believed that the cation radius of americium is more nearly comparable to that of promethium or neodymium than europium (see table 1). The logSi J calculated from the the same data is —0.35. 

In recent years, the quaternary ammonium-functionalized ILs have been investigated widely because of its cheap, low toxicity properties. A kind of ILs was designed and synthesized by tricaprylmethylammonium chloride (Aliquat 336 or A336) and traditional carboxylic acid and phosphoric acid extractant [2]. Because the cation and anion of this kind of ILs are all the functional group for the REEs extraction, we called them bifunctional ionic liquid extractants (Bif-ILEs). Bif-ILEs could be synthesized by acid/base neutralization, and this reaction process was under mild condition, with easier purification and good yield (about 70-80 %). 

---