Efficiency of extraction

Hence one extraction with 100 ml. of benzene removes 3 0 g. (or 75 per cent.) of the n-butyric acid, whilst three extractions remove 3 5 g. (or 87-5 per cent.) of the total acid. This clearly shows the greater efficiency of extraction obtainable with several extractions when the total volume of solvent is the same. Moreover, the smaller the distribution coefficient between the organic solvent and the water, the larger the number of extractions that will be necessary. 

Lewis directed subterranean resei voir studies to improve the efficiency of extracting oil from the ground. He designed the first bubble tower to effect more precise and efficient fractionation operations and provided important assistance in developing one of the first continuous thermal cracking process. 

The efficiency of extraction was observed to be inversely proportional to the corn cob particle size. This was expected because the size reduction corresponds to an increase in total particle surface area. An increase in the time of the alkaline extraction and in the NaOH concentration also improves the efficiency of xylan extraction. This happened because when the NaOH concentration was lower, the xylan present in corn cobs could not be fully dissolved in the solution. Thus, it resulted in lower efficiency of xylan extraction. However, when the NaOH concentration was higher than 2 M, the yields decreased with continuously increasing of the NaOH concentration. This is probably due to the alkaline degradation of xylan chains, proceeding at the higher NaOH concentration, which indicated that the ideal NaOH concentration in the extraction was between 1.5 and 1.8 M (Unpublished data). 

To obtain anthocyanins closer to their natural state, a number of researchers have used neutral solvents for initial extraction such as 60% methanol, n-butanol, cold acetone, mixtures of acetone, methanol, and water, or simply water. Methanol is the most common solvent used for anthocyanin extraction. Metivier et al. (1980) compared the efficiency of extraction with three different solvents (methanol, ethanol, and water) and different acids, and found that methanol extraction was 20% more effective than ethanol and 73% more effective than water when used for anthocyanin recovery from grape pomace. 

Extraction efficiency. The efficiency of extractions of imidacloprid from vegetables and crops decreases in the order acetonitrile > acetone > ethyl acetate. Acetonitrile is not a suitable extraction solvent because of the large number of co-eluting peaks on the chromatograms on HPLC at 210 or 270 nm. ... 

Contimious liquid extraction techniques are used when the sample volume is large, the distribution constant is small, or the rate of extraction is slow. The efficiency of extraction depends on many factors including the viscosity of the phases, the magnitude of the distribution constant, the relative phase volumes, the interfacial surface area, and the relative velocity of the phases. Numerous continuous extractors using llghter-than-water and heavier-than-water solvents vee been described [3,2 7,42,73,74]. Generally, either the ligi Pr or heavier density... 

When using any solvent extraction system, one of the most important decisions is the selection of the solvent to be used. The properties which should be considered when choosing the appropriate solvent are selectivity distribution coefficients insolubility recoverability density interfacial tension chemical reactivity viscosity vapour pressure freezing point safety and cost. A balance must be obtained between the efficiency of extraction (the yield), the stability of the additive under the extraction conditions, the (instrumental and analyst) time required and cost of the equipment. Once extracted the functionality is lost and... 

In extraction from a polymer/additive solid matrix the rate-determining step in the extraction process is governed by the interaction of the solvent of sufficient dissolution power with the matrix and the removal of the analyte (cf. Section 3.4.1.3). There appears to exist a direct relationship between degree of swelling and efficiency of extraction. The amount of C02 absorbed depends on temperature, pressure and the polymer concerned. Crystalline polymers are-not surprisingly-plasticised less... 

The efficiency of extraction is mainly dependent on temperature as it influences physical properties of the sample and its interaction with the liquid phase. The extraction is influenced by the surface tension of the solvent and its penetration into the sample (i.e. its viscosity) and by the diffusion rate and solubility of the analytes all parameters that are normally improved by a temperature increase. High temperature increases the rate of extraction. Lou et al. [122] studied the kinetics of mass transfer in PFE of polymeric samples considering that the extraction process in PFE consists of three steps ... 

This chapter reviews recent findings about the health benefits of phytochemicals present in fruits, vegetables, nuts, seeds, and herbs, including phenolics, carotenoids, sterols, and alkaloids. These phytochemicals are extracted using emerging technologies such as supercritical carbon dioxide (SC-CO2) extraction, PEF, MWE, HPP, UE, and OH. The impact of important parameters related to sample preparation (particle size and moisture content) and extraction process (temperature, pressure, solvent flow rate, extraction time, and the use of a cosolvent) on the efficiency of extraction and on the characteristics of the extracted products is evaluated based on an extensive review of recent literature. The future of extraction of phytochemicals is certainly bright with the... 

Pellegrini N, Colombi B, Salvatore S, Brenna, OV, Galavema G, Del Rio D, Bianchi M, Bennett RN and Brighenti F. 2007. Evaluation of antioxidant capacity of some fruit and vegetable foods efficiency of extraction of a sequence of solvents. J Sci Food Agric 87(1) 103—111. 

In this method volatile organic matter in seawater is concentrated on a Tenax GC solid adsorbent trap and dry-ice trap in series. The trapped organic material is then desorbed and oxidised to carbon dioxide, which is measured with a non-dispersive infrared analyser. A dynamic headspace method was used for the extraction with the assistance of nitrogen purging. Dynamic headspace analysis [184] is an efficient extraction procedure. The efficiency of extraction... 

Efficiency of Extraction. Selectivity of Extraction. Extraction Systems. Extraction of Uncharged Metal Chelates. Methods of Extraction. Applications of Solvent Extraction. 

Successive extractions, whilst increasing the efficiency of extraction of both solutes, may lead to a poorer separation. For example, if DA = 102 and I)v = 10 one extraction will remove 99.0% of A and 9.1% of B whereas two extractions will remove 99.99% of A but 17% of B. In practice, a compromise must frequently be sought between completeness of extraction and efficiency of separation. It is often possible to enhance or suppress the extraction of a particular solute by adjustment of pH or by complexation. This introduces the added complication of several interrelated chemical equilibria which makes a complete theoretical treatment more difficult. Complexation and pH control are discussed more fully in Chapter 3. 

LLE has been used in the past for the extraction of pesticides from environmental water samples [17]. However, its application in the extraction of waste-water samples is scarce due to the low efficiency of extraction, especially for polar analytes. Because of the vast amount of surfactants and natural products present in wastewater samples, emulsions are formed which complicate the process of extraction and lead to low extraction recoveries. However, there have been some useful applications of LLE to wastewater analyses. For example, LLE was found to be effective for the isolation of herbicide and pesticide organic compounds from industrial wastewater samples and also from complex matrices [18]. 

Another point to be considered is the form in which the protein-containing food is consumed and the efficiency of extraction or use of the protein in human diet. When this is considered, most of the seed-type foods, beans and legumes, have efficiencies which overcome their lowered production potential. Thus, these foods can be directly consumed and this results in a very efficient use in the human body. Many grasses and... 

Tests were carried out to compare the efficiency of extraction results obtained using a manual weighing and sample preparation method, and the reagent adder and sample preparation unit. Extracts of four replicates of ten soils were prepared by each method and analysed for nitrate- plus nitrite-nitrogen by a diazotisation and coupling reaction with sulphanilic acid and N-(l-naphthyl)ethylenediamine and ammonium-nitrogen by an indophenol method. These methods are described fully by Greaves et al. [48]. 

The overall efficiency of LED emission depends on three factors which vary between the different types of LEDs. These are the efficiency of electron-hole production, the radiative efficiency of recombination, and the efficiency of extraction of the optical signal from the junction. 

Recovery measurements are one of the most difficult aspects in organic analysis. These measurements are often completed, with the minimum number of replicate determinations over a limited concentration range, to justify optimistically the use of a method. Experiments designed to obtain the efficiency of the analytical method often implicitly assume that this also includes the efficiency of extraction from the matrix [366]. 

The basic requirement is to estimate how much of the analyte has been removed from the natural matrix by a given extraction technique. However, the widespread practice of simply adding a known amount of the analyte to the matrix, usually in an organic solvent, prior to extraction and subsequent analysis, does not answer this question. This type of spiked sample analysis determines the accuracy and precision of the subsequent analytical steps, but does not necessarily measure the efficiency of extraction. 

To determine the efficiency of extraction, it is imperative that the pollutant is bound to the matrix in a similar configuration to that which exists in the environment. The extraction efficiency can then be measured for that analyte in a specific matrix configuration. At present, water is the only matrix where this can be achieved in a relatively straightforward way. The analytes are added below the surface of the sample in a small volume of water miscible solvent. The water must be completely mixed and allowed to stand at least overnight prior to extraction to allow the pollutants to come into equilibrium with the other organic materials, particularly humic matter. The spiked water sample must be analyzed... 

Fig. 8.11 McCabe-Thiele diagram showing the effect of reduced efficiency of extraction.

There followed a brief discussion of equipment for carrying out solvent extraction in industrial practice, both by stagewise and differential contact. Some of the first principles for the design of differential contactors were outlined and the part played by the efficiency of extraction in continuous equipment was discussed. Finally there was an outline of methods for the control of solvent loss which forms probably the most important environmental aspect of the application of solvent extraction. 

Note The efficiency of extraction increases by increasing the number of operations using only a small quantity of the extracting liquid at each time. 

An opinion often quoted in the literature is that by its extraction ability [C4Qlm][PFg] is mainly similar to 1-octanol, and typically the efficiency of extraction is somewhat lower. However, at closer examination, the correlation of the distribution ratio for the same compounds extracted from the aqueous solution to [C4Cilm][PPg] and to 1-octanol seems to be not particularly impressive (Figure 9.4 see Refs 14 and 15). 

Figure 9.6 Efficiency of extraction of various compounds into imidazolium ILs (optimal conditions). Abbreviations BMIm— l-butyl-3-methylimidazolium, C4CjIm BM2Im—l-butyl-2,3-dimethylimidazolium, C4CjCjIm.

Reversed micelles can be used to concentrate water-soluble materials in the water pool of SCCO2. The extraction of water-soluble vitamins into reversed micelles has been examined. The efficiency of extraction was strongly affected by the extraction temperature and the concentration of reversed micelles, and the selectivity depended on the size of micelles. Water-soluble vitamins could be efficiently and rapidly extracted. The selective extraction of a model mixture of vitamins from pharmaceutical preparations was also demonstrated. Moreover, the usefulness of the proposed method for the determination of vitamins in various commercial tablets was also demonstrated. Using this method, the surfactant remains mixed with the extracted com-... 

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