Mixing process batch

To produce highly purified phosphatidylcholine there are two industrial processes batch and continuous. In the batch process for producing phosphatidylcholine fractions with 70—96% PC (Pig. 4) (14,15) deoiled lecithin is blended at 30°C with 30 wt % ethanol, 90 vol %, eventually in the presence of a solubiHzer (for example, mono-, di-, or triglycerides). The ethanol-insoluble fraction is separated and dried. The ethanol-soluble fraction is mixed with aluminum oxide 1 1 and stirred for approximately one hour. After separation, the phosphatidylcholine fraction is concentrated, dried, and packed. 

First, let us consider batch mixing processes, as exemplified by ordinaiy laboratory practice in solution kinetics. A portion of one solution (say, of the substrate) is added by pipet to a second solution (containing the reagent) in a flask, the flask is shaken to achieve homogeneity, and then samples are withdrawn at known times for analysis, or the solution is subjected to continuous observation as a function of time, for example, by spectrophotometry. For reactions on a time scale (measured by the half-life) of hours or even several minutes, the time consumed in these operations is a negligible portion of the reaction time, but as the half-life of the reaction decreases, it becomes necessary to consider these preliminary steps. Let us distinguish three stages ... 

FIGURE 35.9 Typical fingerprint of a final batch-mixing process data obtained from a GK160SUK with fixed rotor speed (18/25 rpm). 

FIGURE 35.11 Typical energy balance of one batch-mixing process on a GK320E mixer (styrene-butadiene rubber/carbon black [SBR/CB] compound). 

A way to narrow the MWD and to approach the structure of dendrimers is the addition of a small fraction of a/-functional initiator, to inimers [40,71]. In this process the obtainable degree of polymerization is limited by the ratio of inimer to initiator. It can be conducted in two ways (i) inimer molecules can be added so slowly to the initiator solution that they can only react with the initiator molecules or with the already formed macromolecules, but not with each other (semi-batch process). Thus, each macromolecule generated in such a process will contain one initiator core but no vinyl group. Then, the polydispersity index is quite low and decreases with / M /Mn l-i-l//. (ii) Alternatively, initiator and monomer molecules can be mixed instantaneously (batch process). Here, the normal SCVP process and the process shown above compete and both kinds of macromolecules will be formed. For this process the polydispersity index also decreases with/,but is higher than for the semi-batch process, M /Mn=Pn//. ... 

OS 41a] ]R 19] ]P 30] Ten different substrates (C4-C8 alcohols) were reacted with rhodium(I)-tris(fn-sulfophenyl)phosphane [110]. The variance in conversions (ranging from about 1-62%) determined was explained by differences in the solubility of the alcohols in the aqueous catalytic layer and by their different intrinsic activities. Chain length and steric/electronic effects of the different alcohols affected their reactivity in a well-known pattern (Figure 4.63). The results obtained correspond to the conversions achieved in a well-mixed traditional batch reactor (40 cm ). They further agreed with data from mono-phasic processing. 

The homogeneity of the product should be addressed. The adequacy of mixing processes should be shown (and confirmed with appropriate process validation data) and potential segregation discussed (as affected by surface properties, crystallinity, particle size, etc.). The Ph Eur uniformity of content requirements should apply to the dosage forms and uniformity of distribution needs to be shown between batches and within batches. The need for appropriate routine tests as part of the release specification should be discussed. 

Large amounts of energy are consumed during the mixing process and this gives rise to large temperature rises in the rubber batch. Internal mixers therefore have cooling channels in the chamber walls, rotors, and sometimes the ram head, to dissipate this heat. The inlet water temperature is controlled in most modem machines, but in many companies this is still not the case. 

Electrochemical Processes. The reductive cleavage of azo-group-containing dyes has been applied on a full scale for the decolorization of concentrates from batch dyeing. Depending on the color, decolorization of up to 80% of the initial absorbance can be obtained. Mixed processes consist of combinations of electrochemical treatment and precipitation by use of dissolving electrodes [43,49]. Such techniques have been described in the literature and have, in part, also been tested on a full scale. Anodic processes that form chlorine from oxidation of chloride have also been proposed to destroy dyes, but care has to be taken with regard to the chlorine and chlorinated products (AOX) formed [114,115]. 

A lot shall consist of one or more batches of NGu, produced by one manufacturer in accordance with the same spec or its revision, under one continuous set of operating conditions. Each batch shall consist of that quantity of NGu that has been subjected to the same mixing process intended to make the final product homogeneous... 

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