Reaction Accompanied Mass Transfer Between Liquid Phases - An Experimental Study

Abstract

<p> This dissertation describes an experimental study of the simultaneous mass transfer and chemical reaction at a plane liquid-liquid interface involving the saponification of simple esters transferring into aqueous caustic solutions. The transfer experiments were carried out with both liquid phases stirred and unstirred respectively.</p> <p> Special emphasis was placed on the stagnant-phase systems. Turbulent reaction layer propagation rates were measured for ester phases (pre-saturated with water) in contact wiith aqueous caustic solutions (at various concentration levels). The distortion of the moire pattern was used to indicate the position of the propagating layer front. The cause and nature of the turbulent layer were elucidated. An apparatus, capable of withdrawing small samples of the liquid with probes precisely located in the aqueous phase, was constructed. Experimental techniques were developed to measure the abnormal concentration profiles of the reactants and the products within the turbulent layer. From the component concentration distribution data, the turbulent layer thicknesses, the reaction zone (within the turbulent layer) thicknesses, the mass transfer rates, and the enhancement factors were deduced. The effects of turbulence in the aqueous phase were estimated in terms of the derived eddy diffusivities and of the differences between the experimentally measured and the theoretically predicted (by molecular diffusion with reaction equation) enhancement factors.</p> <p> In the steady state transfer study using stirring in both phases, transfer rate data and enhancement factor data were obtained for three formate-sodium hydroxide systems.</p> <p> In addition to the mass transfer studies, a preliminary investigation on the diffusion coefficient measurement in binary and ternary liquid systems employing the moire pattern method was carried out. A diffusion cell was designed and built to enable the quick acquisition of the experimental data with reasonable accuracy.</p>