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Solvent extraction method

Conventional methods of polymer extraction use large quantities of solvents as in shake-flask extraction or a Soxhlet extraction apparatus. For all classical extraction methods, solvent selectivity, in general, is low, i.e. solvents with high capacity tend to have low selectivity. In reflux extractions, which are still quite popular in polymer applications, the polymer is refluxed with a hot solvent, which disperses it to provide a solvent phase containing additives. In these conditions solvents are at their atmospheric boiling point. These methods are lengthy and labour intensive. Fractional extraction is based on solvents with increasing solvent power (cf. also [81]). [Pg.62]

Constants arc listed under the indicated alkali metal cation. Unless otherwise noted, all constants were obtained on the molarity scale at 25 C by solvent extraction methods. Solvents are divided into dry and wet categories according to water content (see Table 11). [Pg.356]

An attempt is made here to give a brief descriptiOTi of important ion extraction methods solvent extraction, ion exchange, ion flotation, cloud point extraction, precipitation, and membrane separation. All these techniques are based on the more or less specific recognition of ions with chemical/physical sites. Depending on the technique, this recognition can originate from... [Pg.1093]

Ion exchange (qv see also Chromatography) is an important procedure for the separation and chemical identification of curium and higher elements. This technique is selective and rapid and has been the key to the discovery of the transcurium elements, in that the elution order and approximate peak position for the undiscovered elements were predicted with considerable confidence (9). Thus the first experimental observation of the chemical behavior of a new actinide element has often been its ion-exchange behavior—an observation coincident with its identification. Further exploration of the chemistry of the element often depended on the production of larger amounts by this method. Solvent extraction is another useful method for separating and purifying actinide elements. [Pg.214]

Analytical and test methods for the characterization of polyethylene and PP are also used for PB, PMP, and polymers of other higher a-olefins. The C-nmr method as well as k and Raman spectroscopic methods are all used to study the chemical stmcture and stereoregularity of polyolefin resins. In industry, polyolefin stereoregularity is usually estimated by the solvent—extraction method similar to that used for isotactic PP. Intrinsic viscosity measurements of dilute solutions in decahn and tetraHn at elevated temperatures can provide the basis for the molecular weight estimation of PB and PMP with the Mark-Houwiok equation, [rj] = KM. The constants K and d for several polyolefins are given in Table 8. [Pg.431]

The PGM concentrate is attacked with aqua regia to dissolve gold, platinum, and palladium. The more insoluble metals, iridium, rhodium, mthenium, and osmium remain as a residue. Gold is recovered from the aqua regia solution either by reduction to the metallic form with ferrous salts or by solvent-extraction methods. The solution is then treated with ammonium chloride to produce a precipitate of ammonium hexachloroplatinate(IV),... [Pg.168]

One patent (64) describes an extraction method to remove both trichloropropane and tetrachloropropyl ether from the dichi orohydrin solution by the use of carbon tetrachloride as a solvent. In this way the by-products are removed from the aqueous phase iato an organic phase from which they can be separated by distillation and disposed of ia a safe and proper manner. [Pg.75]

We have found that in the system of presulfate initiator, the PVAc latexes are not dissolved transparently in the methanol-water mixture [8], and in the system of HPO initiator, the extraction of the polymer from the PVAc latex films with acetone greatly depends on the polymerization condition [9]. These results suggest that if a polymerization method can be found in which the grafting polymerization of VAc onto PVA is controlled to the minimum, a large portion of PVAc in the latex film will have a chance of extraction with solvents. In this Chapter, the preparations of the unique porous films from the PVAc latexes containing PVA as a protective colloid by an extraction of the PVAc particles with acetone and the characteristic properties of the porous films are summarized. [Pg.167]

Automation of solvent extraction. Although automatic methods of analysis do not fall within the scope of the present text, it is appropriate to emphasise here that solvent extraction methods offer considerable scope for automation. A fully automated solvent extraction procedure, using APDC, for the determination of... [Pg.174]

An interesting consequence of selective sorption is that conditions for partition chromatography arise which may enhance the normal ion exchange separation factors. This aspect has been utilised by Korkisch34 for separation of inorganic ions by the so-called combined ion exchange-solvent extraction method (CISE). [Pg.201]

Separation techniques may have to be applied if the given sample contains substances which act as interferences (Section 21.10), or, as explained above, if the concentration of the element to be determined in the test solution is too low to give satisfactory absorbance readings. As already indicated (Section 21.10), the separation methods most commonly used in conjunction with flame spectrophotometric methods are solvent extraction (see Chapter 6) and ion exchange (Chapter 7). When a solvent extraction method is used, it may happen that the element to be determined is extracted into an organic solvent, and as discussed above it may be possible to use this solution directly for the flame photometric measurement. [Pg.802]

Metal-chloride complexes studied by ion-exchange and solvent extraction methods, Part I and Part II. Y. Marcus, Coord. Chem. Rev., 1967, 2,195-238 (228) and 257-297 (239). [Pg.35]

Various extraction methods for phenolic compounds in plant material have been published (Ayres and Loike, 1990 Arts and Hollman, 1998 Andreasen et ah, 2000 Fernandez et al., 2000). In this case phenolic compounds were an important part of the plant material and all the published methods were optimised to remove those analytes from the matrix. Our interest was to find the solvents to modily the taste, but not to extract the phenolic compounds of interest. In each test the technical treatment of the sample was similar. Extraction was carried out at room temperature (approximately 23 °C) for 30 minutes in a horizontal shaker with 200 rpm. Samples were weighed into extraction vials and solvent was added. The vials were closed with caps to minimise the evaporation of the extraction solvent. After 30 minutes the samples were filtered to separate the solvent from the solid. Filter papers were placed on aluminium foil and, after the solvent evaporahon, were removed. Extracted samples were dried at 100°C for 30 minutes to evaporate all the solvent traces. The solvents tested were chloroform, ethanol, diethylether, butanol, ethylacetate, heptane, n-hexane and cyclohexane and they were tested with different solvent/solid ratios. Methanol (MeOH) and acetonitrile (ACN) were not considered because of the high solubility of catechins and lignans to MeOH and ACN. The extracted phloem samples were tasted in the same way as the heated ones. Detailed results from each extraction experiment are presented in Table 14.2. [Pg.283]

Seed oils and waxes are more commonly extracted by SFE. It is the most suitable technique for non-polar compounds such as oils and waxes instead of other organic solvents, and it avoids the presence of solvent residues after extraction. Both extraction methods, the classical and SFE, stiU need the additional purification step of the extract, increasing the cost of the final product. [Pg.311]

Figure 5.2 Environmental scores of reduction steps in routes B and C (Scheme 5.1) according to the Eco-lndicator95 evaluation method (Figure 2 in reference [11 ]). Ml = catalyst, M2 = reduction, M3 = catalyst removal, M4 = extraction, M5 = solvent drain off, M5 = rectification, M7 = enantiomeric purification, M8 = solvent recycling. Reproduced from Jodicke [11 ], Copyright 1 999, with permission from Elsevier. Figure 5.2 Environmental scores of reduction steps in routes B and C (Scheme 5.1) according to the Eco-lndicator95 evaluation method (Figure 2 in reference [11 ]). Ml = catalyst, M2 = reduction, M3 = catalyst removal, M4 = extraction, M5 = solvent drain off, M5 = rectification, M7 = enantiomeric purification, M8 = solvent recycling. Reproduced from Jodicke [11 ], Copyright 1 999, with permission from Elsevier.
Extraction of residues from soil samples is much more difficult than their extraction from plant or water samples. The pesticide residues in the soil exist often in several forms as bound residue , which may affect the extraction efficiency of pesticides from the soil. Then, various extraction methods such as organic solvent extraction, Soxhlet extraction, sonication extraction, microwave dissolution and supercritical fluid extraction (SEE) are used. Some extraction methods are described in the following. [Pg.337]

Several extraction methods for water samples are applicable, such as solvent extraction, SPE using a cartridge and disk and solid-phase microextraction (SPME). [Pg.339]

Thus, organic solvent extraction methods for the extraction of pesticides from water samples can be replaced by the SPE method using Ci8 and PS-2. Ethobenzanid, clomeprop, naproanilide and their acidic metabolites are determined by a multi-residue analytical method using Cig or PS-2 cartridge extraction after acidification of the water samples with hydrochloric acid or other acidic media, followed by HPLC or LC/MS detection. [Pg.340]

Sample preparation techniques vary depending on the analyte and the matrix. An advantage of immunoassays is that less sample preparation is often needed prior to analysis. Because the ELISA is conducted in an aqueous system, aqueous samples such as groundwater may be analyzed directly in the immunoassay or following dilution in a buffer solution. For soil, plant material or complex water samples (e.g., sewage effluent), the analyte must be extracted from the matrix. The extraction method must meet performance criteria such as recovery, reproducibility and ruggedness, and ultimately the analyte must be in a solution that is aqueous or in a water-miscible solvent. For chemical analytes such as pesticides, a simple extraction with methanol may be suitable. At the other extreme, multiple extractions, column cleanup and finally solvent exchange may be necessary to extract the analyte into a solution that is free of matrix interference. [Pg.630]

Specific extraction methods are used to prepare the analyte for immunoassay by freeing the analyte fromboth specific and nonspecific interferences. Supercritical fluid extraction has been used to decrease the amount of solvent waste generated. Solid-phase extraction has gained popularity, and many different supports are available. One promising extraction and concentration method is immunoaffinity chromatography, which will be addressed later. [Pg.694]

SFE. SFE has been established as the extraction method of choice for solid samples. The usefulness of SFE for soil samples has been demonstrated for carbamate,organophosphorus and organochlorine pesticides. However, SFE is more effective in extracting nonpolar than polar residues. In order to obtain a greater extraction efficiency for the polar residues of imidacloprid, the addition of 20% methanol as modifier is required. Extraction at 276 bar and 80 °C with a solvent consisting of supercritical carbon dioxide modified with methanol (5%) for 40 min gives a recovery of 97% (RSD = 3.6%, n = 10). It is possible to use process-scale SFE to decontaminate pesticide residues from dust waste. ... [Pg.1140]

The facilitated ion transfers of some alkaline earth metals have been also studied in the DCE systems by the cyclic voltammetry. These systems perhaps have not been studied by any solvent extraction methods yet. Typical voltammograms in the N15C5 diffusion-control systems are shown in Fig. 6. The aqueous supporting electrolyte was MgCl2 instead of MgS04 in these measurements because BaS04 precipitated. [Pg.636]


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