Matrix sorption

Sorption occurs and then ion-exchange or hydrophobic or hydrogen bonding occurs between an analyte and a gel matrix. Sorption retards analyte mobility. Flence, observed elution volumes increase for sorbed analytes (suggesting incorrectly lower MWs) as compared to those controlled by size exclusion alone. In the case of a... 

The term sorption combines matrix sorption and surface sorption. Matrix sorption can be described as the relatively unspecific exchange of constituents contained in water into the porous matrix of a rock ( absorption ). Surface sorption is understood to be the accretion of atoms or molecules of solutes, gases or vapor at a phase boundary ( adsorption ). In the following only surface sorption will be addressed more thoroughly. 

Many organic contaminants, including chlorinated solvents, are removed from solution by sorption onto the aquifer matrix. Sorption of dissolved contamination onto the aquifer ma-... 

Persistence of pesticides in the environment is controlled by retention, degradation, and transport processes and their interaction. Retention refers to the abihty of the soil to bind a pesticide, preventing its movement either within or outside of the soil matrix. Retention primarily refers to the sorption process, but also includes absorption into the soil matrix and soil organisms, both plants and microorganisms. In contrast to degradation that decreases the absolute amount of the pesticide in the environment, sorption processes do not affect the total amount of pesticide present in the soil but can decrease the amount available for transformation or transport. 

Eor a food container, the amount of sorption could be estimated in the following way. Eor simple diffusion the concentration in the polymer at the food surface could be estimated with equation 3. This would require a knowledge of the partial pressure of the flavor in the food. This is not always available, but methods exist for estimating this when the food matrix is water-dorninated. The concentration in the polymer at the depth of penetration is zero. Hence the average concentration C is as from equation 9. 

Pd(II) was shown to be separated from Ni(II), Cr(III) and Co(III) by ACs completely, and only up to 3 % of Cu(II) and Fe(II) evaluate from solution together with Pd(II), this way practically pure palladium may be obtained by it s sorption from multi-component solutions. The selectivity of Pd(II) evaluation by ACs was explained by soi ption mechanism, the main part of which consists in direct interaction of Pd(II) with 7t-conjugate electron system of carbon matrix and electrons transfer from carbon to Pd(II), last one can be reduced right up to Pd in dependence on reducing capability of AC. 

Theoretical and applied aspects of microwave heating, as well as the advantages of its application are discussed for the individual analytical processes and also for the sample preparation procedures. Special attention is paid to the various preconcentration techniques, in part, sorption and extraction. Improvement of microwave-assisted solution preconcentration is shown on the example of separation of noble metals from matrix components by complexing sorbents. Advantages of microwave-assisted extraction and principles of choice of appropriate solvent are considered for the extraction of organic contaminants from solutions and solid samples by alcohols and room-temperature ionic liquids (RTILs). 

Selective sorption by the filler sorption of one of the matrix components (residual monomer, low molecular homologs, various impurities) may lead to plasticization of the boundary layers and appearance of soft interphases [115,116]. 

The anomalous increase of the water uptake observed in Fig. 10 when approaching equilibrium at 60 °C has been associated to the damage. The abrupt upturn of the sorption curve may be explained considering a possible crazing of the low crosslinked internodular matrix induced by the differential swelling stresses that can arise, at high water contents, between areas of different crosslinking density. 

If, hypothetically, the whole rock was taker to be porous, a /a would be 1 (volume sorption) this is typical for the migration in a chromatographic column. In reality, only part of the rock matrix could be available for sorption, typically giving aj/ap = 10-3 (surface sorption) for the conditions used in our studies (66). Other representative values are p =2500 kg/m3, p =1000 kg/n and e 0.001. r W... 

Another major drawback of polysaccharides is their hydrophilic nature leading to low degrees of adhesion between fiber and matrix [11]. Moisture absorption takes place by three types of mechanisms namely diffusion, capillarity, and transport via micro cracks [2]. Among the three, diffusion is considered to be the major mechanism. Water absorption largely depends on the water-soluble or hygroscopic components embedded in the matrix, which acts as a semipermeable membrane. While, fiber/matrix adhesion and fiber architecture also affect the moisture absorption. The results of the water sorption experiment showed an interesting trend. The extent of water uptake was not very significant and also did not increase linearly with amount of filler (Table-2). 

Although in many. soils with tow P availability, significant desorption of sparingly soluble Pi forms requires at least millimolar concentration levels of specific carboxylates (e.g., citrate, oxalate) in the soil solution, much lower concentrations (0.1 mM) were necessary to reduce. soil adsorption of Pi, which was applied simultaneously with carboxylates (100). Thus, competition of carboxylates with Pi for P sorption sites in the soil matrix may be a mechanism that can. 

Lesser retardation factor (slowing of migration with groundwater due to sorption to aquifer matrix). 

The result shown in Eq. (54) is a square root of time relationship for moisture uptake. Mulski [20] demonstrated that for sodium glycinate in a hydrophobic porous matrix, moisture sorption follows Eq. (54). 

The nitrogen-containing carbonaceous replicas of siliceous materials were prepared and studied with the nitrogen adsorption, TEM, TGA, XPS, and EDX methods. The carbons obtained using SBA-15 as a matrix exhibited well-developed and highly ordered porous structures. Those from the MLV material showed lower sorption capacities and 3-D structures less ordered as in the case of the SBA-15 replicas. 

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