Time of breakthrough

Yokosuka, O. Events occurring at the time of breakthrough hepatitis during lamivudine treatment for chronic hepatitis (editorial). J. Gastroenterol. 2004 39 813-814... 

Calculate the approximate time of breakthrough for a single-stage, 5000-lb canister of Filtrasorb. Assume that breakthrough occurs at an insignificantly short time before the bulk of the carbon is exhausted. 

Rodrigues has presented empirical and semi-empirical approaches which may be used to design ion exchange columns when the solute in the feedstream is Cq and the flow-rate is Mq. The breakthrough point is usually set at the point where the effluent concentration increases to 5 % of Cq. The design equations relate the total equilibrium ion exchange capacity (0 to the volume of resin required (V ) to the time of breakthrough (t ). 

Consider the adsorber of Example 9.7. If the bed length is increased to 3.0 m, estimate the new time of breakthrough assuming constant LUB. 

The degree of column utilization before breakthrough requires a knowledge of the shape of the exchange zone boundary or exchange zone front at the time of breakthrough. Approximately,... 

Fig. 14. Sketch of breakthrough curve showing break time / and the method of calculation of the stoichiometric time // and LUB. From ref. 7.

Chemical permeation is rated in tests under EN 374-3. The breakthrough time of a chemical through a glove is quoted as a permeation index ... 

Adsorption for gas purification comes under the category of dynamic adsorption. Where a high separation efficiency is required, the adsorption would be stopped when the breakthrough point is reached. The relationship between adsorbate concentration in the gas stream and the solid may be determined experimentally and plotted in the form of isotherms. These are usually determined under static equilibrium conditions but dynamic adsorption conditions operating in gas purification bear little relationship to these results. Isotherms indicate the affinity of the adsorbent for the adsorbate but do not relate the contact time or the amount of adsorbent required to reduce the adsorbate from one concentration to another. Factors which influence the service time of an adsorbent bed include the grain size of the adsorbent depth of adsorbent bed gas velocity temperature of gas and adsorbent pressure of the gas stream concentration of the adsorbates concentration of other gas constituents which may be adsorbed at the same time moisture content of the gas and adsorbent concentration of substances which may polymerize or react with the adsorbent adsorptive capacity of the adsorbent for the adsorbate over the concentration range applicable over the filter or carbon bed efficiency of adsorbate removal required. 

Stochastic or probabilistic techniques can be applied to either the moisture module, or the solution of equation (3) — or for example the models of Schwartz Crowe (13) and Tang et al. (16), or can lead to new conceptual model developments as for example the work of Jury (17). Stochastic or probabilistic modeling is mainly aimed at describing breakthrough times of overall concentration threshold levels, rather than individual processes or concentrations in individual soil compartments. Coefficients or response functions and these models have to be calibrated to field data since major processes are studied via a black-box or response function approach and not individually. Other modeling concepts may be related to soil models for solid waste sites and specialized pollutant leachate issues (18). 

Adsorption/desorption kinetics the time of the adsorption-regeneration cycle greatly depends on the kinetics of the C02 adsorption-desorption profile, which is measured in breakthrough experiments. Sorbents that adsorb and desorb C02 in a shorter time are preferred as these reduce the cycle time as well as the amount of sorbent required, and ultimately the cost of C02 separation. 

Example 13 Estimation of Breakthrough Time With reference to Example 9, determine the 10 percent breakthrough time and the column dynamic binding capacity if the column is 20 cm long. 

The probable route and structures included are identified using the following hierarchical criteria 1) direct and shortest structural connection, 2) interconnection of faults, 3) average breakthrough time of tracer which is directly correlated to tracer concentration and 5) the location of major and minor feed zones within the respective wells. 

The first indication of breakthrough of the C02 occurred in samples from all 3 U-tube samplers on 17 July, 2008 with slightly elevated C02 content and the presence of tracers. In mid-August, U2 became gassy and the pH dropped significantly. There was no coincident change in either the alkalinity or cation concentrations. By early September, U2 had converted entirely to gas lift. Over the same time frame, as the pH decreases, the per cent of C02 in the U2 samples (for gas exsolved from the water sample through decrease from formation to atmospheric pressure) increased from 4% to >40%. 

Compatibility Charts Permeation and penetration data supplied by the manufacturers of protective clothing to indicate chemical resistance and breakthrough time of various garment materials as tested against a battery of chemicals. 

K-HTC is used more successfully for sorption-enhanced water-gas shift [27]. Breakthrough of CO occurs at the same time as breakthrough of CO2 [37] and the amount of steam necessary for desorption can be kept relatively low [27]. A commercial high-temperature shift catalyst can be used. During desorption in steam, the catalyst can be oxidized, so it is necessary to add some hydrogen to the purge steam [27]. 

The retardation term can also be expressed as the ratio of the breakthrough time of an adsorbed pollutant relative to the elution time of a non-adsorbed tracer. In addition, parameter R can be used to estimate the number of pore volumes of flow required to achieve breakthrough, assuming that breakthrough of a non-adsorbed tracer would occur at one pore volume of flow. 

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