Extraction , 205?. Separation liquid-liquid


The entropically driven disorder-order transition in hard-sphere fluids was originally discovered in computer simulations [58, 59]. The development of colloidal suspensions behaving as hard spheres (i.e., having negligible Hamaker constants, see Section VI-3) provided the means to experimentally verify the transition. Experimental data on the nucleation of hard-sphere colloidal crystals [60] allows one to extract the hard-sphere solid-liquid interfacial tension, 7 = 0.55 0.02k T/o, where a is the hard-sphere diameter [61]. This value agrees well with that found from density functional theory, 7 = 0.6 0.02k r/a 2 [21] (Section IX-2A).  [c.337]

Weigh out 3 8 g. of metallic sodium, cut it into small pieces, and add it to 75 ml. of good-quality (preferably absolute) methanol contained in a 250 ml. bolt-head flask at once attach the flask to an efficient reflux water-condenser. Considerable heat is evolved by the dissolution of the sodium, and the alcohol boils vigorously under reflux no attempt should be made to cool the alcohol (unless the condenser tends to choke ), otherwise a considerable time will elapse before the last traces of the sodium dissolve. Then cool the clear solution of sodium methoxide in ice-water, and add 15 g. of phenol, which will rapidly dissolve to give sodium phenoxide (or phenate) when the mixture is gently shaken. Now add ii ml. (25 g., i-i mols.) of methyl iodide and some fragments of unglazed porcelain, re-attach the flask to the reflux condenser, and boil the solution gently on a water-bath for one hour. Then remove the flask from the water-bath, and rearrange the condenser for direct distillation, connecting it through a knee-tube to the flask (as in Fig. 59, p. 100, or Fig. 23(0), p. 45). Replace the latter on the water-bath, and distil off the excess of methanol as completely as possible. Pour the residual liquid in the flask into 100 ml. of cold water contained in a separa-ting-funnel, and wash out the flask with another 50 ml. of water, adding these washings also to the liquid in the funnel. Then extract the anisole by shaking with about 40-50 ml. of ether, Run oflF the lower aqueous layer, and shake the ethereal solution with an equal volume of 10% aqueous sodium hydroxide solution this removes unchanged phenol, and abo any traces of free iodine present, leaving the ethereal solution quite colourless. Run oflF the sodium hydroxide solution as completely as possible, and shake the ethereal solution with an equal volume of water to remove the last traces of the sodium hydroxide. Separate the ethereal solution,  [c.219]

Whereas light erudes are preferred in present-day refining operations, inereasingly, heavy petroleum sources also must be processed to satisfy ever-inereasing needs. These range from commereially usable heavy oil (California, Venezuela, ete.) to the huge petroleum reserves locked up in shale or tar sand formations. These more unconventional hydroearbon aeeumulations exceed the quantity of lighter oil present in all the rest of the oil deposits in the world together. One of the largest aeeumulations is located in Alberta, Canada, in the form of large tar sand and carbonate rock deposits containing some 2.5-6 trillion barrels of extremely heavy oil called bitumen. There are large heavy oil accumulations in Venezuela and Siberia, among other areas. Another vast, commercially significant reservoir of oil is the oil shale deposits loeated in Wyoming, Utah, and Colorado. The praetieal use of these potentially vast reserves will depend on finding economical ways to extract the oil (by thermal retorting or other processes) for further processing. Alberta tar-sand oil is already processed in commercially viable large-scale operations.  [c.130]

Weigh out 3-8 g. of metallic sodium, cut it into small pieces, and add it to 75 ml. of good-quality (preferably absolute) methanol contained in a 250 ml. bolt-head flask at once attach the flask to an efficient reflux water-condenser. Considerable heat is evolved by the dissolution of the sodium, and the alcohol boils vigorously under reflux no attempt should be made to cool the alcohol (unless the condenser tends to choke ), otherwise a considerable time will elapse before the last traces of the sodium dissolve. Then cool the clear solution of sodium methoxide in ice-water, and add 15 g. of phenol, which will rapidly dissolve to give sodium phenoxide (or phenate) when the mixture is gently shaken. Now add ii ml. (25 g., i-i mols.) of methyl iodide and some fragments of unglazed porcelain, re-attach the flask to the reflux condenser, and boil the solution gently on a water-bath for one hour. Then remove the flask from the water-bath, and rearrange the condenser for direct distillation, connecting it through a knee-tube to the flask (as in Fig. 59, p. 100, or Fig. 23(0), p. 45). Replace the latter on the water-bath, and distil off the excess of methanol as completely as possible. Pour the residual liquid in the flask into too ml. of cold water contained in a separa-ting-funnel, and wash out the flask with another 50 ml. of water, adding these washings also to the liquid in the funnel. Then extract the anisole by shaking with about 40-50 ml. of ether. Run off the lower aqueous layer, and shake the ethereal solution with an equal volume of 10% aqueous sodium hydroxide solution this removes unchanged phenol, and also any traces of free iodine present, leaving the ethereal solution quite colourless. Run off the sodium hydroxide solution as completely as possible, and shake the ethereal solution with an equal volume of water to remove the last traces of the sodium hydroxide. Separate the ethereal solution,  [c.219]

Typically, grape skin extract has a specific gravity of 1.13 g/mL at 20°C, a solids content of 28—32° Brix (=t3°), a pH of 3.0, and a color strength as anthocyanin of about 1.25% (as measured at 520 nm ia pH 3.0 citrate buffet). Grape skin extract is also available as spray-dried powders with color values three to four times those of the liquid. The properties and uses of grape skin extract ate similar to those of grape color extract.  [c.450]

Trace residue analysis of compounds in various matrices is an essential process for evaluation of different exposures to such toxicants, in which, preparation of samples is one of the most time-consuming and error-prone aspects prior to chromatographic analyses. A comparative study of sample preparation was performed to preconcentrate urinary 1-hydroxypyrene (1-OFIP) as a major metabolite and biological indicator of the overall exposure to polycyclic aromatic hydrocarbons (PAFIs) generated by various industrial and environmental processes. To perform this study, solid phase extraction (SPE) was optimized with regard to sample pFI, sample concentration, loading flow rate, elution solvent, washing solvent, sample volume, elution volume, and sorbent mass. The present approach proved that, 1-OFIP could be efficiently retained on CIS sorbent based on specific interaction. Further study employed methanol to extract the analyte from spiked urine. Along with, a nonclassic form of liquid-liquid extraction (LEE) also was optimized with regard to solvent type, solvent volume, extraction temperature, mixing type, and mixing duration. The results showed that, 1-OFIP could be relatively well extracted by methanol at optimum time of 2 minutes based on moderate specific interaction. At the developed conditions, obtained recovery of SPE was 99.96%, while, the EEE extraction recovery did not exceed 87.3% and also, based on applied sample volume, the limit of detection (EOD) achieved by SPE was 0.02 p.g/1 showing at least ten times less than that of EEE. The procedures were validated with three different pools of spiked urine samples showed a good reproducibility over six consecutive days as well as six within-day experiments for both developed methods as suitable results were obtained for CV% (less than 3.1% for SPE and between 2.8% and 5.05% for EEE). In this study, a high performance liquid chromatography (HPEC), using reverse-phase column was used. The mobile phase was methanol/water am at constant flow rate of 0.8 ml/min and a fluorescence detector was used, setting at 242 nm and 388 nm. Although the recovery and EOD were obtained for SPE method shows more efficiency, such results for EEE is also relatively efficient and can be applied for majority of similar studies. However, there is a significant difference between the obtained recoveries of SPE and EEE (P<0.05), showing that, SPE is superior.  [c.378]

Yeast Extracts. Autolysis ia yeast cells is iaduced by raising the temperature of a cell suspeasioa to 44—55°C at which temperature, the yeast cells die, but their hydrolytic enzymes remain active. During this process, proteias, carbohydrates, and nucleic acids are hydrolyzed and solubilized. Commercial yeast autolyses generally last over 10 h. At the end of autolysis, the iasoluble cell wall materials can be separated from the solubilized products by centrifugation. The resulting extract is evaporated to a paste of about 75% soHds or spray dried to a powder. The powder contains 50—80% oligopeptides and amino acids amino nitrogen may account for 25—45% of the total nitrogen, with the rest consisting mainly of nucleic acids.  [c.394]


Modern analytical chemistry (2000) -- [ c.212 , c.212 ]