Breakthrough time

Most dynamic adsorption data are obtained in the form of outlet concentrations as a function of time as shown in Figure 18a. The area iebai measures the removal of the adsorbate, as would the stoichiometric area idcai, and is used to calculate equiUbrium loading. For constant pattern adsorption, the breakthrough time and the stoichiometric time ( g), are used to calculate LUB as (1 — (107). This LUB concept is commonly used... 

The effluent concentration history is the breakthrough curve, also shown in Fig. 16-3. The effluent concentration stays at or near zero or a low residual concentration until the transition reaches the column outlet. The effluent concentration then rises until it becomes unacceptable, this time being called the breakthrough time. The feed step must stop and, for a regenerative system, the regeneration step begins. 

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 ... 

Breakthrough time In the context of chemical protective clothing, the rime between initial contact of the chemical on the barrier material surface and the analytical detection of the chemical on the other side of the material. 

Selection of polymers used in the manufacture of chemical protective clothing (CPC) is a complex task. It involves evaluating breakthrough times and permeation rates in conjunction with such task requirements as tactility and resistance to cuts and abrasion. But, it involves a more basic problem — that of deciding which polymer(s), in the absence of test data, might be most likely to resist permeation by a specific chemical. These decisions are faced not only by users of CPC (e.g., industrial hygienists), but also by poljnner chemists and CPC manufacturers. 

Forsberg s electronic book consists of information from over 5,000 permeation tests on 6A0 chemicals or mixtures of chemicals. Over 7,000 breakthrough times and/or permeation rates are recorded. Along with this information are over 25,000 pieces of associated data such as the test material, manufacturer, model number, thickness, comments, a performance index number, and references. Over 200 different models of CPC are represented. 

Estimated Protection Time is derived using an expert decision module that evaluates breakthrough time, permeation rate, and the toQdc properties of the test chemical. 

Sensitive analytic procedures enable detection and measurement of very low tracer levels. In tracer studies, an identifiable tracer material is injected through one or more injection wells into the reservoir being studied. Water or other fluid is then injected to push the tracer to one or more recovery wells in the reservoir. The output of the recovery wells is monitored to determine tracer breakthrough and flow through the recovery wells. Analysis of the breakthrough times and the flows yields important information regarding how to perform the secondary or enhanced recovery processes. 

The breakthrough time observed in the NOx concentration profile (obtained by addition of the NO and N02 concentrations) indicates that during the initial part of the pulse, the NO fed to the reactor is completely stored on the catalyst surface. 

In all cases, NO and N02 are detected at the reactor outlet and it clearly appears that the breakthrough time in the NO outlet concentration and the N02 formation markedly depend on the Ba loading of the catalysts. 

The model inadequacy was particularly evident for the systems having different Ba loadings, which showed an increase in the breakthrough time associated with similar NO oxidizing capacity. Work is currently in progress in order to gain a better adequacy of the model to our data in particular the nitrite route has also been included to provide an additional NO adsorption pathway, which is in line with obtained data, and preliminary results obtained in this direction seem to be promising. 

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). 

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. 

Breakthrough Time The elapsed time between initial contact of a hazardous chemical with the outside surface of a protective clothing material and the time at which the chemical can be detected at the inside surface of the material. 

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. 

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. 

Tb = the breakthrough time referring to Fig. 26, this is defined as the intercept on the dimensionless time axis of the tangent to the curve at the point of inflexion. 

---