Fluid—solid extraction

Modifications of user properties have various origins. First, the process of size reduction itself may change the shape of the particles. Some properties, like taste, are sometimes directly induced by the particle size at the bio-sensor s scale. For example, it is now widely known that the gustative quality of chocolate is related to particle size. Another direct consequence of size reduction is an increase of the external specific surface area, that is widely used to enhance the rate of transport phenomena, for example in the case of dissolutions or in fluid/solid extractions. For a given particle size distribution, powder properties may be a consequence of the particles shape. 

Tilden and Company, Formulce for Making Tinctures, Infusions, Syrups, Wines, Mixtures, Pills, c.. Simple and Compound, from the Fluid Solid Extracts Prepared at the Laboratory of Tilden Co. (New York Tilden, 1861). 

Besides the theoretical interest in the unusual phase behavior encountered in these systems, the principles involved can be applied in operations wherein the nonideality is intentionally created. The magnitude of solubility of a compound of low volatility in a gas above its critical temperature. .. is sufficient to consider the gas as an extracting medium, that is fluid-liquid or fluid-solid extraction analogous to liquid-liquid extraction and leaching. In this case the solute is removed and the solvent recovered by partial decompression. Thus compression of a gas over a mixture of compounds could selectively dissolve one compound, permitting it to be removed from the mixture. Partial decompression of the fluid elsewhere would drop out the dissolved compound, and the gas could be reused for further extraction. 

Fluid-solid extraction, also called leaching, is used to separate a substance from a solid matrix by solution into a suitable solvent. The solvent is either a liquid, for example, hot water or an organic solvent, or a supercritical fluid, most notably water or carbon dioxide. 

Table 3.3.12 Critical data, density, diffusion coefficient, and viscosity of gases typically used for high-pressure fluid-solid extraction processes. Data from Sattler (1986).

A method which uses supercritical fluid/solid phase extraction/supercritical fluid chromatography (SE/SPE/SEC) has been developed for the analysis of trace constituents in complex matrices (67). By using this technique, extraction and clean-up are accomplished in one step using unmodified SC CO2. This step is monitored by a photodiode-array detector which allows fractionation. Eigure 10.14 shows a schematic representation of the SE/SPE/SEC set-up. This system allowed selective retention of the sample matrices while eluting and depositing the analytes of interest in the cryogenic trap. Application to the analysis of pesticides from lipid sample matrices have been reported. In this case, the lipids were completely separated from the pesticides. 

The most widely employed techniques for the extraction of water samples for triazine compounds include liquid-liquid extraction (LLE), solid-phase extraction (SPE), and liquid-solid extraction (LSE). Although most reports involving SPE are off-line procedures, there is increasing interest and subsequently increasing numbers of reports regarding on-line SPE, the goal of which is to improve overall productivity and safety. To a lesser extent, solid-phase microextraction (SPME), supercritical fluid extraction (SEE), semi-permeable membrane device (SPMD), and molecularly imprinted polymer (MIP) techniques have been reported. 

In liquid-solid extraction (LSE) the analyte is extracted from the solid by a liquid, which is separated by filtration. Numerous extraction processes, representing various types and levels of energy, have been described steam distillation, simultaneous steam distillation-solvent extraction (SDE), passive hot solvent extraction, forced-flow leaching, (automated) Soxh-let extraction, shake-flask method, mechanically agitated reflux extraction, ultrasound-assisted extraction, y -ray-assisted extraction, microwave-assisted extraction (MAE), microwave-enhanced extraction (Soxwave ), microwave-assisted process (MAP ), gas-phase MAE, enhanced fluidity extraction, hot (subcritical) water extraction, supercritical fluid extraction (SFE), supercritical assisted liquid extraction, pressurised hot water extraction, enhanced solvent extraction (ESE ), solu-tion/precipitation, etc. The most successful systems are described in Sections 3.3.3-3.4.6. Other, less frequently... 

Principles and Characteristics The principle of solid-fluid-vortex extraction, a recent development [152], is based on the creation of a relatively high filtration pressure as a result of cooling off a vapour chamber in a boiler vessel in such a way that there is (ideally) complete condensation and the extractive fluid is forced through a filter and/or extraction material at nearly one atmosphere in the case of open extractor systems and at more than one atmosphere in the case of closed extractor systems (cf. hydrostatic pressures up to 0.01 bar in Soxhlet). 

The intermittent solid-fluid-vortex extraction method [153] consists of four stages ... 

This cycle of vaporisation of the solvent, condensation, extraction, and vacuum-filtration may be repeated any number of times in a solid-fluid serial extractor. The occurrence of an extractive material fluid bed as a result of the flow of boiling hot vapour provides for effective extraction, while pressure filtration provides for short cycle times. This functional principle makes it possible to achieve filtration pressures which are 50-100 times more effective than when using the Soxhlet method, where only the low hydrostatic pressure of the extractive fluid operates. Solid-fluid-vortex extraction according to the proprietary FEXTRA (Feststoff Extraktion) principle is low cost. 

Advantages of intermittent extraction are similar to those of solid-fluid-vortex extraction. A disadvantage is caking of the polymer in the case of a high polymer concentration in the extract or by loss of extraction fluid. Interlaboratory comparison is restricted. 

Pressurized fluid Sample extracted with Organic compounds in solid... 

Ho JS, Tang PH, Eichelberger JW, et al. 1993. Determination of organic compounds in water by liquid solid extraction followed by supercritical fluid elution and capillary column gas chromatography/mass spectrometry. Denver, CO American Chemical Society, 313-315. 

A solution of flavoring materials extracted from flowers, roots, bark, fruit, etc. It may be alcoholic or non-alcoholic solid extract or fluid extract. These materials are frequently concentrated and standardized, e.g. Gentian extract. 

James et al. (2003) performed laboratory experiments in which aqueous fluids were reacted with natural samples of unaltered MORE (5 Li = +4.6) and a quartzofeldspathic mud/turbidite mixture (5 Li = +1.3). The starting fluids had elemental compositions generally intermediate between seawater and hydrothermal fluids, and were isotopically light (5 Li = -5.5). The initial fluid/solid was 4. Fluid samples were extracted as the experiments were raised to 350°C over 400-500 h, and then during cooling (c. 740 h total). In both experiments Li was removed from solution at low temperatures, but the isotopic composition of the fluids... 

Plots for yield of hydrogen from supercritical fluid (water) extraction, pyrolysis gasification (water/solid = 2) of beech wood at different temperatures... 

Several emerging processes may be applicable for treatment of oily drilling muds prior to disposal. One process being tested in Europe involves the use of an electric distillation kiln to break down solids-laden oil-based drilling muds [13]. Another process uses critical fluid to extract oil and organics from oily sludges so that they can be landhlled [34]. Copa and Dietrich [14] treated a sample of spent drilling mud with wet air oxidation. The COD content was reduced by 45 to 64% and the dewaterability of the mud was improved. 

Flow of Two Fluids. The major applications are in absorption, extraction, and distillation, with and without reaction. Other applications, also quite important, are for shell-and-tube or double-pipe heat exchangers, and noncatalytic fluid-solid reactors (blast furnace and ore-reduction processes). 

We were supported in our thesis by the work of Huddelston et al In order to achieve phase separation, they employed a salting out principle with good success. We employed a polyalcohol backbone and achieved phase separation by reacting the terminal alcohol groups with isocyanates. This was done after the addition of crosslinking chenficals yielded a solid polyol, which, as we will show in subsequent chapters, has the extractive properties we sought. Additional processing techniques allowed us to build an open-cell structure that permitted the flow of fluids and extracted the pollutants. 

The shrinking-core model (SCM) is used in some cases to describe the kinetics of solid and semi-solids-extraction with a supercritical fluid [22,49,53] despite the facts that the seed geometry may be quite irregular, and that internal walls may strongly affect the diffusion. As will be seen with the SCM, the extraction depends on a few parameters. For plug-flow, the transport parameters are the solid-to-fluid mass-transfer coefficient and the intra-particle diffusivity. A third parameter appears when disperse-plug-flow is considered [39,53],... 

If the temperature is too low, the solid cocoa butter formed this second phase, but with higher temperatures two fluid phases are in equilibrium one is rich in CO2 and the other is rich in cocoa butter. Kokot et al. [5] showed that at 313 K and 20 MPa, the mass fractions of CO2 for these two phases are 0.44 and 0.98. When working with two fluid phases and without stirring, the results of the experiments depend on the position of the outlet pipe of the first vessel top or bottom. If the fluid is extracted from the top of the vessel, the cocoa butter powder is produced from the richest phase in CO2. Conversely, it is the cocoa butter rich phase which is extracted from the bottom. If the mixture is homogenised by... 

To understand any extraction technique it is first necessary to discuss some underlying principles that govern all extraction procedures. The chemical properties of the analyte are important to an extraction, as are the properties of the liquid medium in which it is dissolved and the gaseous, liquid, supercritical fluid, or solid extractant used to effect a separation. Of all the relevant solute properties, five chemical properties are fundamental to understanding extraction theory vapor pressure, solubility, molecular weight, hydrophobicity, and acid dissociation. These essential properties determine the transport of chemicals in the human body, the transport of chemicals in the air water-soil environmental compartments, and the transport between immiscible phases during analytical extraction. 

The phase behavior of solids in supercritical fluids has practical significance as well as academic interest. Since the mid-1970 s, it has been recognized that supercritical fluids can be useful as solvents for commercial-scale extractions. While a variety of applications are documented in the literature (2,6), supercritical-fluid (SCF) extraction has been particularly useful in upgrading petroleum fractions (7), extracting volatile components from coal (8), and deashing oil shale (9) and coal liquids (10). The... 

ECD = electron capture detector FID = flame ionization detector GC = gas chromatography HRGC = high resolution gas chromatography LC-APCI-MS = liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry LSE = liquid-solid extraction MS = mass spectrometry PVC = polyvinyl chloride SFE = supercritical fluid extraction... 

The formalism of nonlocal functional density theory provides an attractive way to describe the physical adsorption process at the fluid - solid interface.65 In particular, the ability to model adsorption in a pore of slit - like or cylindrical geometry has led to useful methods for extracting pore size distribution information from experimental adsorption isotherms. At the moment the model has only been tested for microporous carbons and slit - shaped materials.66,67 It is expected that the model will soon be implemented for silica surfaces. 

Cells are grown either in suspension in a free or immobilized form 102), or by adherence to a solid surface 100). Materials used for promoting surface-dependent cell growth are glasses, metals, plastics, carbohydrate polymers etc. the media used contain substances such as blood plasma, amniotic fluids, tissue extracts, etc.103). Recent developments in animal cell culture are aimed at the improvement of strains and culture techniques, medium optimization, and scale-up. In contrast to plant cell culture, animal cell culture has already found its technical application. Large-scale... 

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