Equilibrium capacity

Adsorption equilibrium of CPA and 2,4-D onto GAC could be represented by Sips equation. Adsorption equilibrium capacity increased with decreasing pH of the solution. The internal diffusion coefficients were determined by comparing the experimental concentration curves with those predicted from the surface diffusion model (SDM) and pore diffusion model (PDM). The breakthrough curve for packed bed is steeper than that for the fluidized bed and the breakthrough curves obtained from semi-fluidized beds lie between those obtained from the packed and fluidized beds. Desorption rate of 2,4-D was about 90 % using distilled water. 

The differences in the rate of adsorption are primarily attributable to the differences in the equilibrium capacity at the various pHs, and the pore diffusion model simulated our data satisfactorily. 

In practice, two to three times the equilibrium capacity tends to be used. 

Much of the early work on the nature of adsorbents sought to explain the equilibrium capacity and the molecular forces involved. Adsorption equilibrium is a dynamic concept achieved when the rate at which molecules adsorb on to a surface is equal to the rate at which they desorb. The physical chemistry involved may be complex and no single theory... 

The equilibrium capacity of an adsorbent for different molecules is one factor affecting its selectivity. Another is the structure of the system of pores which permeates the adsorbent. 

Equilenin [517-09-9] Equilibrium capacity Equilibrium constant Equilibrium line Equilibrium theory Equimate... 

Since benzene is not likely to undergo hydrogen bonding, it was expected that Z200H would be suitable. There was, however, some uncertainty about the selective adsorption of the water over the acid, so some very preliminary static equilibrium capacity data were generated. 

Run Zeolon 500, gms Bed Length cm Flow Rate cc/min SLV cc/min Inlet Water ppm Equilibrium Capacity, % MTZ cm Equilibrium Time, min... 

Analyses reported on a dry basis are calculated on the basis that there is no moisture associated with the sample. The moisture value (ASTM D-3173 ISO 331 ISO 589 ISO 1015 ISO 1018 ISO 11722) is used for converting as determined data to the dry basis. Analytical data that are reported on a dry, ash-free basis are calculated on the assumption that there is no moisture or mineral matter associated with the sample. The values obtained for moisture determination (ASTM D-3173 ISO 589) and ash determination (ASTM D-3174) are used for the conversion. Finally, data calculated on an equilibrium moisture basis are calculated to the moisture level determined (ASTM D-1412) as the equilibrium (capacity) moisture. 

As the ligand-protein interaction takes place at the internal surface of porous adsorbents, kinetics and equilibrium of the interaction should be independent of the interstitial voidage within an adsorbent bed. Therefore the equilibrium capacity of an adsorbent will not be influenced by different experimental configurations e.g. batch stirred tank, batch fluidized bed, frontal application to packed or fluidized beds. The major difference arises from the medium from which the protein is isolated. As fluidized beds are used for whole broth adsorption, the properties of the broth have to be considered regarding the possible influence of components which are removed in conventional primary recovery steps and therefore are not present during the initial chromatography operations in a standard downstream process. These are on one hand nucleic... 

Sorbent Sourceb Equilibrium Capacity Type (g succinic acid/L) (g/g) ... 

According to Fetter (1988), the following three scenarios can be used to describe the relationship between precipitation and infiltration rates (1) when the total precipitation rate is lower than the equilibrium infiltration capacity all of the precipitation reaching the land surface should infiltrate (2) when the precipitation rate is higher than the equilibrium capacity and less than the initial infiltration capacity (at the start of the precipitation event) all of the precipitation will infiltrate initially and (3) when the precipitation rate is greater than the initial infiltration capacity there is an immediate accumulation of water on land. In general, when the precipitation rate exceeds infiltration capacity, overland flow of water occurs, commonly referred to as Horton overland flow (HOF) (Horton, 1933, 1940). 

At 26 C (P/Po = 0.4) the equilibrium loading for n-butane Is 1.17 mmoles/g. This loading does not differ greatly from the lsobutane equilibrium capacity (1.01 mmoles/g) suggesting that these Rb-offretlte crystals are probably free from salt occlusion and/or stacking faults. 

Equilibrium capacity for adsorption of organic solutes on carbon can be predicted to increase with decreasing temperature since adsorption reactions are exothermic. The differential heat of adsorption, AH, is defined as the total amount of heat evolved in the adsorption of a definite quantity of solute on an adsorbent. Heats of vapor phase adsorption... 

While the temperature dependence of equilibrium capacity for adsorption is defined by the parameter AH, the dependence of rate of adsorption is usually expressed in terms of activation energy, E. Rate of adsorption is related to the activation energy by the equation,... 

The effects of temperature on the equilibrium capacity of active carbon for adsorption of 2,4-D and DNOSBP have been studied. The data are plotted in Figure 11, and the experimentally determined heats of adsorption are listed in Table IV. The values for AH for the 2,4-D and DNOSBP are remarkably similar, and as one would anticipate from considering the thermodynamics of adsorption, both values are negative. In view of the general range of the values for AH it may be anticipated that normal temperature variations in practical applications will not significantly affect ultimate capacity for sorption of organic pesticides on carbon. 

Figure 11. Temperature dependence of capacity for adsorption Equilibrium capacities for adsorption of DNOSBP and 2,4-D are plotted on a logarithmic scale vs. the reciprocal of temperature, °K.

Figure 12. Isotherm for DNOSBP Equilibrium capacity for adsorption of DNOSBP is represented in terms of iimoles per gram of carbon on the left ordinate and in terms of mg./gram on the right ordinate. A calculated Langmuir isotherm is drawn through the experimental data.

When the mass transfer zone is a major portion of an adsorbent bed, the equilibrium capacity is poorly utilized. A lead—trim configuration uses the adsorbent more fully. The feed flows successively through a lead bed and then a trim bed. The lead bed is nearly exhausted before it is taken out of service to be regenerated. When a lead bed is removed from adsorption, the trim bed becomes the lead, and a fully regenerated bed becomes the new trim bed... 

This approach has several drawbacks. The extractant gradually contaminates the ion-exchange resin and gradually permeates the seawater. The ion-exchange capacity of the resin is used ineffectively, because of the relatively low selectivity of Dowex 50 cation exchangers for Mg relative to Na in the presence of seawater. The equilibrium capacity of Dowex 50x8 toward Mg by sorption fix>m seawater does not exceed 1 mg-equiv/cm of the resin bed. 

The similar basicity and nature of functional groups of fibrous and granular anion exchangers lead to essentially equal dynamic and equilibrium capacities relative to sulphur dioxide and, consequently, to a general mechanism of the SO2 sorption ... 

As seen from Fig. 6, an equilibrium capacity of the fibrous anion exchanger is essentially unaffected with increasing gas flow rate and amount to 0.8 mole of S02/eqv. It is usual that in the adsorption processes, the dynamic sorbent capacity in this case decreases. However, at the rate of 6.0 m/min it remains sufficiently high and is 0.4 mole of S02/eqv. 

Fig. 7. Equilibrium capacity of the HCO j form of the SBF anion exchanger towards SO2 versus gas flow concentration. Gas flow rate, W = 6.6 m/min gas flow humidity, G = 85 rel.% sorbent layer height, h = 7 mm anion exchanger moisture content is 11.8 mole of H20/g-eqv...

At relative gas humidity, G < 20 rel.%, which corresponds to accumulation of 2.6 mole of H20/g-eqv. in the polymer phase, absorption of SO9 by the fibrous anion exchanger does not occur. An increase in humidity of the purified air from 20 to 50 rel.% (2.6 mole of H20/g-eqv. < aj q < 4.8 mole of ll90/g-eqv.) is accompanied by an intensive increase in the dynamic and equilibrium capacity of the fibrous anion exchanger towards SO9. A further increase in moisture content of the polymer phase up to the maximum, 11.8... 

The selection of adsorbents is critical for determining the overall separation performance of the above-described PSA processes for hydrogen purification. The separation of the impurities from hydrogen by the adsorbents used in these processes is generally based on their thermodynamic selectivities of adsorption over H2. Thus, the multicomponent adsorption equilibrium capacities and selectivities, the multi-component isosteric heats of adsorption, and the multicomponent equilibrium-controlled desorption characteristics of the feed gas impurities under the conditions of operation of the ad(de)sorption steps of the PSA processes are the key properties for the selection of the adsorbents. The adsorbents are generally chosen to have fast kinetics of adsorption. Nonetheless, the impact of improved mass transfer coefficients for adsorption cannot be ignored, especially for rapid PSA (RPSA) cycles. 

The size and surface area of the adsorbent particles Smaller particles have larger service areas per unit mass this results in a higher equilibrium capacity, but also in a higher pressure drop (flowthrough bed). 

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