Intensifying micromixing in a semi-batch reactor using a Rushton turbine

The 'iodide-iodate' reaction scheme has been used to ascertain the effectiveness of micromixing in a semi-batch reactor when feeding with pipes rotating and discharging continuously into the region of highest local specific energy dissipation rate, epsilon(T). The results are compared with those obtained using a fixed pipe at the equivalent position and at other positions including near the top surface, the most convenient position industrially. The results show significant intensification, i.e., a seven-fold reduction in 'waste product', between the most convenient fixed feed pipe position and the rotating pipes, even at the modest specific power input of similar to 1.0 W/kg. This mode of addition also ensures that feeding is always into a constant value of epsilon(T), whereas with a static pipe close to the impeller the reactants are being fed in a region where epsilon(T) varies cyclically. This difference in the epsilon(T) values experienced by the two modes of addition poses problems for previous models of micromixing in the literature linking selectivity to local specific energy dissipation rates. (c) 2004 Elsevier Ltd. All rights reserved.