Titration-batch reaction, automatic

Another approach to investigating the mechanisms of Pb immobilization by PR employed an automatic titration-batch reaction (Melamed et al., 2000). In this case, PR was dissolved previously at a given pH. During the process, the lag between the pH drop and the adjustment by the titrator to the equilibrated pH could have contributed to a degree of nonequilibrium dissolution. At all pH values studied, as soon as Pb was added, the system pH dropped. The drop in pH was approximately 0.7, 2, and 3 units, at equilibrium pH values of 3.7,... 

Fig. 5.2a shows examples of the results obtained on the dissolution of 8-AI203. In batch experiments where pH is kept constant with an automatic titrator, the concentration of AI(III)(aq) (resulting from the dissolution) is plotted as a function of time. The linear dissolution kinetics observed for every pH is compatible with a process whose rate is controlled by a surface reaction. The rate of dissolution is obtained from the slope of the plots. 

In addition to the analysis of the thermal stability of the perchloric acid organic reaction media mixtures, a procedure was worked out to determine the fate of the perchloric acid by chlorine analysis of the batch, effluent streams, etc. Preliminary analyses on selected process samples showed no tendency for perchloric acid to concentrate in recycle material and therefore build up in the reactor. A total of less than 1% of the initial charge of perchloric acid (total chlorides calculated as perchloric acid) was found in the combined recovered acid-ester and olefin fractions. Less than 1 % of the initial charge of perchloric acid was found in the finished ester. The analytical method used was an oxygen bomb decomposition, followed by titration of chlorides with 0.0liV silver nitrate, using a recording automatic titrator. The eventual fate of the perchloric acid catalyst was... 

Conversion (o) ee (ee of substrate). Reaction was performed in a 2 L bioreactor at 30 °C and 200 rpm using an isopropyl ether-water biphasic system with 100 mM ( )-MPGM and 900 U of chitosan-SmL. The pH was automatically controlled at 8.0-8.3 hy titrating 2% ammonia. The immobilized lipase was reused in new reactions after ee of the last run reached 99.9%. From the 7 batch of reaction, 15 g of fresh immobilized lipase (corresponding to io% of the initial amount, ca. 90 U) was supplemented at the beginning of each reaction cycle. After the 12 batch of reaction, 15 g of used immobilized lipase was substituted by 15 g of fresh lipase (ca. 90 U). The partial renewal of the immobilized biocatalyst was continued for 10 cycles (12 -21 ). 

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