Sieves separators

Despite the difference ia the nature of the surface, the adsorptive behavior of the molecular sieve carbons resembles that of the small pore zeoHtes. As their name implies, molecular sieve separations are possible on these adsorbents based on the differences ia adsorption rate, which, ia the extreme limit, may iavolve complete exclusion of the larger molecules from the micropores. 

Ellis, L., Aromatic hydrocarbons in crude oil and sediments Molecular sieve separations and biomarkers, RhD thesis, Curtin University of Technology, 1994. 

Winnowing/sieving separation before drying is recommended at elevated contents of weeds, unripe grain, straw, soil, etc. Winnowing or other cleaning techniques will reduce the risk of damp pockets. This is especially important in slow dryers. 

Molecular sieving Separation on n- and isoparafins using 5A zeolite Separation of xylenes using zeolite... 

CE is a family of techniques similar to those found in conventional electrophoresis zone electrophoresis, displacement electrophoresis, isoelectric focusing (IEF), and sieving separations. Other modes of operation unique to CE include micellar electrokinetic chromatography (MEKC) and capillary electrochromatography (CEC). 

One of the major advantages of CE as a separation technique is the wide variety of separation modes available. Analytes can be separated on the basis of charge, molecular size or shape, pi, or hydrophobicity. The same CE instrument can be used for zone electrophoresis, IEF, sieving separations, isotachophoresis, and chromatographic techniques such as MEKC and capillary electrokinetic chromatography. This section provides a brief description of each separation mode. Zone electrophoresis, IEF, and sieving are the primary modes used for protein separations, and these will be discussed in detail in the following sections. 

Exclusion chromatography involves separation of sample components according to the molecular size. Recent techniques are gel permeation and sieving separation. 

Different ways have been proposed to prepare zeolite membranes. A layer of a zeolite structure can be synthesized on a porous alumina or Vycor glass support [27, 28]. Another way is to allow zeolite crystals to grow on a support and then to plug the intercrystalline pores with a dense matrix [29], However, these two ways often lead to defects which strongly decrease the performance of the resulting membrane. A different approach consists in the direct synthesis of a thin (but fragile) unsupported monolithic zeolite membrane [30]. Recent papers have reported on the preparation of zeolite composite membranes by hydrothermal synthesis of a zeolite structure in (or on) a porous substrate [31-34]. These membranes can act as molecular sieve separators (Fig. 2), suggesting that dcfcct-frcc materials can be prepared in this way. The control of the thickness of the separative layer seems to be the key for the future of zeolite membranes. 

Existing literature and data will be used to avoid personal or institutional bias. One system involves relatively inert (nitrogen) physisorption on chars of interest as sorbents, catalysts, molecular sieves, separation substrates, storage media, etc. All of the sorption data presented here exist in tabular form, such that verification of this work and development of alternate theories, verification, and methodology is facilitated. 

Zeolite materials are used commercially as shape/ size selective catalysts in the petrochemical and petroleum refining industry, and as molecular sieving separation media for gases and hydrocarbons. For both applications, zeolites are used in powder composite form such as pellets and granules. In this entry, we focus on zeolite membranes. We define zeolite membranes as a continuous phase of zeolite-based materials (pure zeolite or composite) that separate two spaces. Zeolite membranes are generally uniform thin films attached to a porous or a nonporous substrate. They can also be self-standing without a substrate. Note that we have included zeolite films and layers on nonporous substrate in this entry because we believe many of the synthesis strategies and applications reported for those nonporous substrates are easily transferred to a porous substrate to prepare a zeolite membrane. 

Dry the soil in an oven at a temperature not exceeding 75°C, since high temperature results in adherence of some soils to the sieves. When dry (usually after 30-40 minutes) transfer the soil from each sieve separately into can boxes, dry overnight in an oven at 105° and weigh. 

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