Solid/liquid mixtures, separation

Separating solid/liquid mixtures Separating liquid/liquid mixtures... 

Add 2.0 g of salicylic acid, 5.0 mL of acetic anhydride, and 5 drops of 85% H3P04 to a 50-mL Erlenmeyer flask. Heat in a water bath at 75°C for 15 minutes. Add cautiously 20 mL of water and transfer to an ice bath at 0°C. Scratch the inside of the flask with a stirring rod to initiate crystallization. Separate aspirin from the solid-liquid mixture by filtering through a Buchner funnel 10 cm in diameter. 

Filtration A process for separating a solid-liquid mixture by passing it through a barrier with fine pores, such as filter paper, 4... 

A significant proportion of products are solids that are separated from a reaction mixture by filtration and centrifugation and purified by crystallization. Recently, more sophisticated techniques for purification (e.g. HPLC) have come in use but crystallization still remains the predominant method. In order to separate solid/liquid mixtures, centrifuges and plane filters (nutches) are u.sed. Generally, filters and centrifuges are operated batchwise. No specific... 

If the machine is separating a solid-liquid mixture, the mean density of the slurry in the bowl should be used in equation 13.131. 

A solid/liquid mixture consisting of very small solid particles suspended in a liquid. The action of gravity or the process of filtration can effect separation of the solid from the liquid. 

The components of mixtures can be separated from one another by taking advantage of differences in the components physical properties. A mixture of solids and liquids, for example, can be separated using filter paper through which the liquids pass but the solids do not. This is how coffee is often made the caffeine and flavor molecules in the hot water pass through the filter and into the coffee pot while the solid coffee grounds remain behind. This method of separating a solid-liquid mixture is called filtration and is a common technique used by chemists. 

When the deviations from ideal behavior become large enough, the liquid mixture separates into two liquid phases. Cooling of this liquid mixture can result in the freezing of a solid, giving (liquid + liquid) and (solid 4-liquid)... 

Even the simplest detersive system is surprisingly complex and heterogeneous. It can nevertheless be conceptually resolved into simpler systems that are amenable to theoretical treatment and understanding. These simpler systems are represented by models for substrate-sohd soil and substrate-liquid soil. In practice, many soil systems include solid-liquid mixtures. However, removal of these systems can generally be analyzed in terms of the two simpler model systems. Although these two systems differ markedly in behavior and structure, and require separate treatment, there are certain overriding principles that apply to both. 

In centrifugal sedimentation, the separation is due to the difference in the density of two or more phases. This is the more important process, where both solid-liquid mixtures and liquid-liquid mixtures can be completely separated. If, however, the separation is incomplete, there is a gradient in the size of the dispersed phase within the centrifuge due to the faster radial velocity of the larger particles. Operated in this way, the centrifuge becomes a classifier. 

An SBC is a vertical, tubular column in which a three-phase (gas-solid-liquid) mixture is used. The slurry phase consists of FT catalysts and FT wax. The syngas flows though the slurry phase in the form of bubbles, as shown in Figure 12.12. The effective heat and mass transfer, low intraparticle diffusion, low pressure drop, and design simplicity are important advantages of this type of reactor. However, considerable problems arise in separating the liquid-phase synthesis products from the catalyst. With their attractive features, the SBC reactors are receiving extensive investment in both R D and commercialization. The concept of SBC is not new. 

In centrifugal filters, separation is effected by directing the solid-liquid mixture on to the inner surface of a perforated, rotating bowl. In fine separations, the inner surface of the bowl will be lined with an appropriate filter medium. 

Until a few years ago, most of the recognized examples of miscible pol3nner blend pairs involved only amorphous components. However, recently numerous blend systems have been identified in which one or both components are crystallizable. The systems of interest here are miscible in the melt state, but upon cooling one or more of the components separates from the mixture as a pure crystalline phase. This form of solid-liquid phase separation represents a different situation than a liquid-liquid miscibility gap since complete miscibility may still exist in the remaining amorphous phase. The objective of this paper is to review some of the pertinent fundamental issues and recent results for miscible blends where crystallization is possible. 

Purchas (1981) has suggested a selection system consisting of three selection steps to produce a shorthand profile of the application from a combination of desk study to define the required duty, and some simple laboratory testing to characterize the separation properties of the solid-liquid mixture. The profile is expressed as a sort of code formed from a group of alphabetic letters (e.g., bdh-BEG-K), and is used in a fourth step to select suitable... 

There are several different separation techniques. Filtration separates undissolved solids from liquids by passing the solid-liquid mixture through solids perforated by pores of a particular size (like a membrane). If the liquid is viscous or the particle size of the solid is too small for filtration, centrifugation can separate such solids from liquids. The liquid samples are loaded into centrifuges, which spin rotors at very high speeds. This process creates pellets from the solids and separates them from liquids. Neither filtration nor centrifugation can separate dissolved components from hquids. 

Another interchangeable term for suspension is slurry, w hich is a concentrated solid-liquid mixture having a broad solid particle size distribution ranging from submicrometers to some hundreds of micrometers [3, 4]. The term concentrated is semiquanlitalive, vaguely referring to where the average separation di.stance between two similar particles is close to or less than the particle size [3]... 

In the chemistry laboratory, mixtures are separated by various methods. Solids are separated from liquids by filtration, which involves pouring a mixture through a filter paper set in a funnel. In chromatography, different components of a liquid mixture separate as they move at different rates up the surface of a piece of paper. 

Membrane extraction involves eoupling of solid/liquid membrane separation with extraction operation. It is mainly used for separation of selective components in liquid streams. The molecules transported through the membrane get extracted into a solvent and are removed from the mixture. It is very useful for the removal of specific contaminants from wastewater and also for the removal of products from fermentation broths. 

Flotation. Flotation is a gravity separation process which exploits differences in the surface properties of particles. Gas bubbles are generated in a liquid and become attached to solid particles or immiscible liquid droplets, causing the particles or droplets to rise to the surface. This is used to separate mixtures of solid-solid particles and liquid-liquid mixtures of finely divided immiscible droplets. It is an important technique in mineral processing, where it is used to separate different types of ore. 

Liquid chromatography is a separation technique based on the selective adsorption on a solid, siiica or alumina for example, or a mixture of the two, of the different components of a liquid mixture. 

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