Batch Absorption

Absorption involves separation of a solute from gas phase to liquid phase. Absorption can involve reactions also. Batch absorption equipment is used to find reaction rate constants and mass transfer coefficients by measuring concentration changes for the liquid composition with respect to time. 

Sg surface area of gas bubbfes per volume of liquid [length 

There are two types of extraction. Solid extraction or leaching involves solids which are leached or extracted by solvent, and liquid extraction where immiscible solvent is used to extract liquid product from the mixture. The following chapter is based on material from [86, 3, 5]. 

There are three processes involved in leaching or solid extraction. Dissolution of solids, separation of solvent from insoluble sohd material, and washing. Most of the leaching plants are operated batchwise. In a batch leaching, the solids are stationary and solvent is flowing through the bed of particles. 

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Henry, P. D. Roberts, R. and Sobel, B. E. Rapid separation of plasma creatine kinase isoenzymes by batch absorption on glass beads. Clin. Chem. (1975), 21, 884-849. 

The isolation technique based on sequential aqueous chromatography was introduced by Stansell and Deutsch They used batch absorption of the nonhaemoglobin proteins on DEAE cellulose for the removal of haemoglobin. The overall procedure was very laborious and time consuming. Therefore, a more convenient method shorter in time was developed The yield of purified SOD was the same as obtained with the Tsuschihashi method. Compared to the latter technique the different operation... 

I Ultrafiltration, Pellicon system, 10,000 MWCO CONCENTRATED ENZYME, 300-500 mL DEAE batch absorption I Ultrafiltration, Amicon cell CONCENTRATED ENZYME 15 mL I HPLC (carboxysulfone column)... 

Batch Absorption Chapter 6 describes briefly the batch absorption operation. This unit operation is based on the solubility difference. Batch absorption is mostly used for finding kinetics and mass transfer coefficients... 

In batch gas absorption, a soluble vapor is absorbed from a mixture by means of a liquid in which the gas is more or less soluble. Unlike distillation, absorption is based on different solubility of the components in liquid and not based on boiling point difference. Absorption followed by reaction in the liquid phase is often used to get more complete removal of a solute from a gas mixture. Although, most of the absorption columns are operated continuously, batch absorption is important in the measurement of reaction rate constants and mass transfer coefficients. These absorption equipment are often carried out in a tank where gas bubbles are dispersed in the liquid phase as shown in Figure 6.1. 

Douglas N. Dean, Michael J. Fuchs, John M. Schaffer, and Ruben G. Car-boneU. Batch absorption of CO2 by free and microencapsulated carbonic an-hydrase. Ind. Eng. Chem., Fundam., 16(4) 452, 1977. 

Batch absorption operations based on the solubility difference... 

The process options reflect the broad range of compositions and gas volumes that must be processed. Both batch processes and continuous processes are used. Batch processes are used when the daily production of sulfur is small and of the order of 10 kg. When the daily sulfur production is higher, of the order of 45 kg, continuous processes are usually more economical. Using batch processes, regeneration of the absorbant or adsorbant is carried out in the primary reactor. Using continuous processes, absorption of the acid gases occurs in one vessel and acid gas recovery and solvent regeneration occur in a separate reactor. 

In a typical batch operation, carbon disulfide is added to four molar equivalents of 25—30 wt % aqueous ammonia in a stirred vessel, which is kept closed for the first one to two hours. The reaction is moderately exothermic and requires cooling. After two to three hours, when substantially all of the disulfide has reacted, the reaction mixture is heated to decompose dithiocarbamate and trithiocarbonate and vented to an absorption system to collect ammonia, hydrogen sulfide, and any unreacted carbon disulfide. 

For an example of a control chart see Fig. 1.31 and Sections 4.1 and 4.8. Control charts have a grave weakness the number of available data points must be relatively high in order to be able to claim statistical control . As is often the case in this age of increasingly shorter product life cyeles, decisions will have to be made on the basis of a few batch release measurements the link between them and the more numerous in-process controls is not necessarily straight-forward, especially if IPC uses simple tests (e.g. absorption, conductivity) and release tests are complex (e.g. HPLC, crystal size). 

Figure 4.23. Comparison of results on four batches using four different methods. The results are grouped according to batch, and within a group, the methods are sulfide precipitation, polarography. X-ray fluorescence, and inductively coupled plasma absorption (left to right).

Three test batches of a chemical were manufactured with the intention of validating the process and having a new product to offer on the market. Samples were put on stability under the accepted ambient (25°C, 60% relative humidity) and accelerated (= stress 40°C, 75% rh) conditions cf. Section 4.20. One of the specification points related to the yellowish tinge imparted by a decomposition product, and an upper limit of 0.2 AU was imposed for the absorption of the mother liquor (the solvent mixture from which the crystalline product is precipitated) at a wavelength near 400 nm. 

The absorption rates of CO2 were measured in such non-aqueous solvents as toluene, NMP, and DMSO with GMA concentration ranging Ifom 0.5 to 3 kmol/m in a semi-batch flat-stirred agitated vessel constructed of pyrex glass of 0.075 m inside diameter and of 0.13 m in height. The apparatus and the experimental procedure are the same as those described by... 

Dynantics of Heat Exchangers, Simple Batch Extraction, Multi-Solute Batch Extraction, Multistage Countercurrent Ctiscade, Extraction Cascade with Backmixing, Countercurrent Extraction Cascade with Reaction, Absorption with Chemical Reaction, Membrane Transfer Processes... 

All piroxicam batches were manufactured in compliance with Good Manufacturing Practices, and three formulations having fast, moderate, and slow dissolution were chosen for comparison to a lot of the innovator s product in a human bioavailability study [100]. The resulting pharmacokinetic data provided still another opportunity to examine the effects of formulation variables. To explore the relationship between the in vitro dissolution of piroxicam from these capsules and in vivo absorption, Polli [ 102] used the following previously described [145] deconvolution-based model ... 

Those aspects critical to the in vivo bioavailability of the product and routine control tests proposed to ensure that the product has consistent bioavailability from batch to batch. Where a product has low in vivo absorption, the evidence should be discussed and a conclusion reached as to whether this is due to intrinsic properties of the active ingredient(s) or whether it is related to the properties of the dosage form concerned. In the case of products intended to have a nonsystemic effect, the potential for systemic absorption may need to be considered. This may involve specific studies to determine the levels of the active ingredient(s) in the blood, plasma, urine, or feces and a discussion of the clinical significance of those results. 

Figure 4.20 Continuous removal of product by stripping synthesis of epoxides from alkenes applying a batch process with resting cells or a fermenter connected to absorption, extraction and distillation...

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