Desorbate treatment

Extraction with Organic solvents Extraction with carbon Sulphur extraction Desorbate treatment by... 

Extraction with Organic solvents Caustic soda solution Supercritical gases Exiiaetion with earbon disulfide or other solvents Percolation with eaustie soda e.g. extraction with supercritical CO2 Sulphur extraction Sulfosorbon process Phenol-loads activated earbon Organic compounds Desorbate treatment by distillation, steam desorption of solvent Phenol separation with subsequent purging S aration of C02/or-ganic compounds... 

Another consideration in the application of absorption as a control technique is the treatment or disposal of the material removed from the absorber. In most cases, the scrubbing liquid containing the VOC is regenerated in an operation known as stripping, in which the VOC is desorbed from the absorbent liquid, typically at elevated temperatures and/or under vacuum. The VOC is then recovered as a liquid by a condenser. 

Of these, the most commonly used for air pollution control are the fixed-bed and canister units. Fixed beds are also used in solvent-recovery applications. Major process steps include adsorption, regeneration, and further treatment of the desorbed organic compounds. Typically, further treatment includes condensation and separation. 

When the temperature of the analyzed sample is increased continuously and in a known way, the experimental data on desorption can serve to estimate the apparent values of parameters characteristic for the desorption process. To this end, the most simple Arrhenius model for activated processes is usually used, with obvious modifications due to the planar nature of the desorption process. Sometimes, more refined models accounting for the surface mobility of adsorbed species or other specific points are applied. The Arrhenius model is to a large extent merely formal and involves three effective (apparent) parameters the activation energy of desorption, the preexponential factor, and the order of the rate-determining step in desorption. As will be dealt with in Section II. B, the experimental arrangement is usually such that the primary records reproduce essentially either the desorbed amount or the actual rate of desorption. After due correction, the output readings are converted into a desorption curve which may represent either the dependence of the desorbed amount on the temperature or, preferably, the dependence of the desorption rate on the temperature. In principle, there are two approaches to the treatment of the desorption curves. 

In the first one, the desorption rates and the corresponding desorbed amounts at a set of particular temperatures are extracted from the output data. These pairs of values are then substituted into the Arrhenius equation, and from their temperature dependence its parameters are estimated. This is the most general treatment, for which a more empirical knowledge of the time-temperature dependence is sufficient, and which in principle does not presume a constancy of the parameters in the Arrhenius equation. It requires, however, a graphical or numerical integration of experimental data and in some cases their differentiation as well, which inherently brings about some loss of information and accuracy, The reliability of the temperature estimate throughout the whole experiment with this... 

There are little data available. The only piece of information consists in rhodium being obtained by the reduction of its derivatives by hydrogen. The metal obtained occludes large quantities of hydrogen. If it is desorbed from hot rhodium, it combusts in air. Thus, the treatment has to be carried out in inert gas. Rhodium is inert, not even fluorine reacts with it. It occludes oxygen, but only reacts slowly when it is hot. It reacts with halogens at very high temperatures. 

Polyaromatic hydrocarbons absorb strongly to humus and other soil components, rendering these contaminants difficult to remove by thermal, physical, or chemical means, and unavailable for biodegradation. To desorb polyaromatic hydrocarbons from soil, surfactant flooding processes and soil-washing processes or treatments to enhance the biodegradation of polyaromatic hydrocarbons have been considered. 

Owing to the fact that organic substances have to be separated from a complex sample, transferred to the mass spectrometer target and desorbed, it seems impossible so far to analyse cross-linked binding media from artwork (e.g. dried oil, aged proteins, cross-linked synthetic polymers). Application of classical methods of sample treatment for... 

Near-well treatments, in which chemicals are injected into producing and sometimes injector wells, where they are intended to react with the reservoir rock. Well stimulation techniques such as acidization, for example, are intended to increase the formation s permeability. Alternatively, producing wells may receive squeeze treatments in which a mineral scale inhibitor is injected into the formation. In this case, the treatment is designed so that the inhibitor sorbs onto mineral surfaces, where it can gradually desorb into the formation water during production. 

The complex formed when a mordant dyeing is aftertreated in a dichromate solution is retained by the wool in preference to the unmetallised mordant dye, which may desorb to some extent during the treatment. The latter is rather unstable in an oxidising solution and quinonoid by-products are often formed. If the chromium complex of the dye is formed from the desorbed dye in solution, this will further complicate the composition of the aftertreatment liquor. Thus reuse of mordant dyeing and aftertreatment baths is not an option. Furthermore, 100% rejection of dichromate ions would be required if the permeate of a membrane process treating the effluent was to be recycled [42]. 

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