Extraction aqueous-phase acidity

Add 1.16 g ergotamine.HCl to 4 ml anhydrous hydrazine and heat one hour at 90°. Add 20 ml water and evaporate in vacuum. Can proceed to the next step or can purify by adding ether and aqueous tartaric acid, basify the aqueous phase and extract aqueous phase with CHC13 to get mainly d-iso-lysergic hydrazide (I). Can... 

If you wish to extract aqueous acetic acid into hexane, is it more effective to adjust the aqueous phase to pH 3 or pH 8 ... 

Figure 17. An empirical model was developed to describe the extraction process, taking account of the observation that [U02(DBP)2(HDBP)2] was the predominant uranyl species in the organic phase at aqueous phase acidities of less than 2 M, while [U02(N03)2(HDBP)2] predominated at higher acidities. The curves derived from this model, and a revised model which took into account the presence of other organic phase species such as H[U02(N03)3] (HDBP), are shown in Figure 18. The latter model gave a good description of the system in the aqueous phase acidity range 1 -7 M.

Figure 3. Effect of CA W equilibrium aqueous phase acidity on DBBP extraction...

A carboxylic acid is more soluble in the organic phase, but its salt is more soluble in the aqueous phase. Acid-base extractions can move the acid from the ether phase into a basic aqueous phase and back into the ether phase, leaving impurities behind. 

The extraction of Zr" by pure TBP/OK phases increases rapidly with aqueous phase acidity so that Dzt for 19% TBP/OK increases from ca. 10 at 0.5 M HNO3 to ca. 10 at 13 M HN03- Satisfactory decontamination from zirconium can thus be achieved using aqueous phase acidities in the range 2-3 M where Dz, will be ca. 0.1. The extraction reaction was described by equation (158) but more recent work also indicates the presence of Zr(0H)2(N03)2 2TBP and Zr(OH)-... 

Thus, the extraction coefficient, E, varies directly with the third power of the concentration of uncombined HDEHP in the organic phase (neglecting activity coefficients) and inversely with the third power of the aqueous phase acidity (H ). 

The acid dependency observed in practice hal been only approximately inverse third power. Impurities in Cleanex feed solutions often cause a departure from ideality (e.g., by common-ion effect or by consumption of some of the HDEHP), and we have not been able to control the extraction of the actinide elements solely by monitoring the aqueous-phase acidity. Fortunately, when processing transplutonium elements, the high specific activity of 21+I+Cm facilitates the detection of that isotope in both phases, thus permitting a rapid determination of the degree of extraction. The extraction coefficients of the trivalent actinides and lanthanides are all quite similar, so the 21+1+Cm serves as an excellent marker for all the extracted ions. 

Sample preparation Condition a 3 mL 500 mg Sep-Pak with 10 mL MeOH and 10 mL water at 3 mL/min (do not allow to dry). 5 mL Serum + 50 p,L 10 p.g/mL ormetoprim in water, vortex for 15 s, allow to stand for 5 min, add 2 mL pH 11 NaH2P04 (pH adjusted with 5 M NaOH), vortex for 10 s, add 30 mL dichloromethane, shake for 10 min, extract aqueous phase again with 20 mL dichloromethane. Combine organic layers and shake them with 10 mL 150 mM sulfuric acid. Remove 8 mL of the aqueous layer and add it to 10 mL phosphate buffer (adjusted to pH 6 with 1M NaOH), add this to the SPE cartridge, wash with 10 mL water, draw air through the cartridge for 1 min, elute with 1 mL MeOH, evaporate the eluate at 50° under a stream of nitrogen, reconstitute the residue in 1 mL mobile phase, filter (0.45 p.m), inject a 50 p.L aliquot. 

Recovery of components through extraction and back-extraction is usually characterized by low energy and reagent consumption but relatively high capital cost. The parameters affecting equipment cost therefore have strong effects on process economics, particularly for low-value products such as mineral acids. Extractant composition affects equipment cost, because (1) the distribution coefficients determine the extractant/aqueous phase volume ratio in extraction and in back-extraction and thereby the... 

The extraction capacity of liquid TBP and TVEX-TBP increases with increase of aqueous phase acidity for 7,9, and 11 mol/1 HCl solutions (Figure 8.23). TBP capacity in TVEX matrix is higher as compared with liquid tri-butylphosphate this difference depends on aqueous phase acidity and becomes maximal (1.5 to 2 times) at 9 mol/L HCl. TVEX-TBP capacity is also higher for Nb extraction for sulfuric media however, dependence of extractant capacity on aqueous phase acidity is dependent on the redox unstability of Nb in sulfuric media [25,26]. 

Isotherms of Ga extraction by TVEX-TBP, TVEX-DIOMP as well as by liquid TBP andDIOMP from 3,5, and 8 mol/L HCl solutions show (Figure 8.25 and Figure 8.26) that extractant equilibrium capacity increases with aqueous phase acidity increase extractant capacity in TVEX matrix is 1.3 to 1.5 times higher as compared with solvent extractant. Enthalpy of gallium extraction from 3 mol/L HCl is -11.7 kJ/mol for TBP and -12.0 kJ/mol for TVEX-TBP. Diffusion coefficient of gallium extraction is 4.210-" mVs for TVEX-TBP (3mol/L HCl) and 5.410-" mVs for TVEX-DIOMP (6 mol/L HCl) [27]. 

TVEX-TBP resins also have shown high capacitive and kinetic properties for Zr and Hf extraction from HNO3 media [28,29], a high separation factor for the couple Zr/Hf The isotherms of Zr and Hf extraction by TVEX-65% TBP under different aqueous phase acidity showed Zr and Hf capacities up to 0.6 mol Zr/mol TBP and 0.3 mol Hf/mol TBP, respectively (Figure 8.30 and Figure 8.31). The particle diffusion coefficients measured were 1.5 10 mVs for Zr and 2.210 " mVs for Hf, respectively, in 6 mol/L nitric solutions. 

Although extraction of lipids from membranes can be induced in atomic force apparatus (Leckband et al., 1994) and biomembrane force probe (Evans et al., 1991) experiments, spontaneous dissociation of a lipid from a membrane occurs very rarely because it involves an energy barrier of about 20 kcal/mol (Cevc and Marsh, 1987). However, lipids are known to be extracted from membranes by various enzymes. One such enzyme is phospholipase A2 (PLA2), which complexes with membrane surfaces, destabilizes a phospholipid, extracts it from the membrane, and catalyzes the hydrolysis reaction of the srir2-acyl chain of the lipid, producing lysophospholipids and fatty acids (Slotboom et al., 1982 Dennis, 1983 Jain et al., 1995). SMD simulations were employed to investigate the extraction of a lipid molecule from a DLPE monolayer by human synovial PLA2 (see Eig. 6b), and to compare this process to the extraction of a lipid from a lipid monolayer into the aqueous phase (Stepaniants et al., 1997). 

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