Extraction dilute fractional

The Grignard reagent is prepared from 6 gms. (2 mols.) of dry magnesium, and 39 gms. (2 mols.) of ethyl iodide (redistilled), as described in Preparation 19, 120 c.cs. of anhydrous ether being used. 23 gms. (1 mol.) of dry, finely divided benzophenone are added, the flask being cooled if the reaction becomes too vigorous. The mixture is then heated 6 hours on a water bath, treated with dilute acid, extracted with ether, the ether removed on a water bath, and the residue fractionated under reduced pressure, the fraction 169°—170° at 18 mms. being separately collected and recrystallised from petroleum ether. 

Many years ago, Liss and Langen (1960a,b) showed that the most highly polymerized yeast PolyP fraction, extractable only with strong alkali (0.05 M) or when kept for a long period with diluted CaCl2 solution, is apparently firmly bound to some cell components other than RNA. The removal of RNA by RNAase had no effect on the extraction rate of this PolyP fraction. It was considered that in this case PolyP was bound to a certain protein. 

Acetals are equilibrium products between aldehydes and alcohols. As discussed by Williams and Strauss (30) acetals generally have less intense aromas than the corresponding alcohols and aldehydes. 1,1,3-Triethoxypropane and diethoxybutan-2-one (derived from acrolein and diacetyl, respectively) are common acetals in the heads fractions from continuous stills acetals from other aldehydes including acetaldehyde, propanal, isobutanal, and isovaleraldeyde are also common (30). The equilibrium between the aldehyde and the acetal is highly dependent on alcohol concentration and pH, again m ng accurate quantitation of either the aldehyde or the acetal dependent on the analytical conditions (e.g., sample dilution, solvent extraction, etc.) (30). 

Dual-Solvent Fractional Extraction As discussed in Commercial Process Schemes, under Introduction and Overview, fractional extraction often may be viewed as combining product purification with product recovery by adding a washing section to the stripping section of a standard extraction process. In the stripping section, the mass transfer we focus on is the transfer of the product solute from the wash solvent into the extraction solvent. If we assume dilute conditions and use shortcut calculations for illustration, the extraction factor is given by... 

In designing of 2D LC x LC systems, the selection of the mobile phase for each chromatographic dimension is of fundamental importance, in order to achieve maximal utilization of the 2D separation space. In contrast to off-line 2D LC procedures, where the collected fraction can be subjected to evaporation, dilution, or extraction, before injection onto the column of the second dimension, the compatibility of the mobile phases in online 2D LC x LC in terms of miscibility, solubility, viscosity, and eluotropic strength is much more important. The mobile phases used in SEC x RPC, SEC x NPC, RP x CEX, RP x AEX RP x CEX, NPC x HILIC, NPC x CEX, and NPC x AEX are compatible (see Figure 16). 

TBP meets most of these requirements except those of low viscosity and a density different from water. These deficiencies are corrected by diluting TBP with a light, saturated hydrocarbon, such as an aromatic-free kerosene. This solvent is the one most commonly used at present in fractional extraction of metals. The physical properties of TBP are summarized in Table 4.5 [FI, S4J. 

Hurd and Saint-James [H5] of the French Atomic Energy Commission have shown that TBP diluted with kerosene is a selective solvent for the fractional extraction of zirconium from hafnium. These workers recommend using an organic phase consisting of 60 v/o (volume percent) TBP and 40 percent refined kerosene, and an aqueous phase 3 TV in nitric acid and... 

Hanfoid [D3]. Nitrite concentration in feed to the HA column of a standard Purex plant was adjusted to route most of the neptunium in inadiated natural uranium into the extract from the HS scrubbing column. Sufficient ferrous sulfamate was used in the partitioning column to reduce neptunium to Np(IV), which followed uranium. This neptunium was separated from uranium by fractional extraction with TBP in the second uranium cycle. The dilute neptunium product was recycled to HA column feed, to build up its concentration. Periodically, irradiated uranium feed was replaced by unirradiated uranium, which flushed plutonium and fission products from the system. The impure neptunium remaining was concentrated and purified by solvent extraction and ion exchange. 

Protein and ash comprised about 10% of the AIS and were found mostly in the dilute alkali extract. The neutral sugars were determined by HPLC and GLC of their sllylated derivatives of the hydrolysate after removal of acid. Arabinose and galactose were found in the dilute alkali extract. Xylose, arabinose, galactose and glucose were all present in the easily hydrolyzable fraction. Glucose was the main sugar component in the fraction dissolved in the 12 M H SO. Carbazol colorimetric method was used to determine the uronlc acids in the fractions. 

More xylose was found in the dilute acid hydrolysate than in the other two fractions. Only about 55 to 70% of the AIS extracted by the dilute alkali can be accounted for by the sum of the sugars and the uronlc acid. The recovery of the dilute acid extract as the monomers was also low, amounting to between 44 and 79%. There were some peaks on the chromatogram of this fraction, but the aggregated integrated area was only around 10% of the total. Peak with retention times close to glucose and mannose were present. 

Analysis of fractional extraction is straightforward for dilute mixtures when the solutes are independent and total flow rates in each section are constant. The external mass balances for the fractional extraction cascade shown in Figure 13-5 are... 

Dll. The fractional extraction system shown in Figure 13-5 is separating abietic acid from other acids. Solvent 1, heptane, enters at c = 1000 kg/h and is pure. Solvent 2, methylcellosolve + 10% water, is pure and has a flow rate of R = 2500 kg/h. Feed is 5 wt % abietic acid in solvent 2 and flows at 1 kg/h. There are only traces of other acids in the feed. We desire to recover 95% of the abietic acid in the bottom raffinate stream. Feed is on stage 6. Assume that the solvents are completely immiscible and that the system can be considered to be very dilute. Equilibrium data are given in Table 13-3. Find N. 

The use of symmetrical flow FFF hyphenated with RI and MALLS detectors to assess the size and shape of sequentially dilute HAc extracted monomeric rich and sonicated HAc extracted polymeric rich wheat proteins was reported by Stevenson et al. - values at peak for the monomeric extract varied from 31,000 to 33,000 and increased to approximately 110,0(X) at later elution times. Results for all five varieties of wheat included in this study were similar for the monomeric wheat protein extracts. The profiles of polymeric extracts for the five wheat samples ranged from 225,000 to 300,000 at peak and increased to approximately 7x10 after 60 min of elution as shown in Fig. 2. values for the polymeric protein fraction showed relatively small changes with increasing elution time (M ), suggesting that the larger polymeric proteins tend toward a more compact structure than the lower polymeric proteins. 

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