The application of the wavefront shearing optical interferometer to diffusion measurements.

摘要

A wavefront shearing optical interferometer has been built in this laboratory, and its use for diffusion measurements is described. In Part I of this work, the application of the interferometer to diffusion in liquid-liquid systems is discussed. Using a flowing-junction cell in conjunction with the interferometer, the following systems were investigated and diffusion coefficients reported over a range of concentrations, sucrose-water; monoethanolamine-water; diethanolamine-water; and triethanolamine-water. A new method for calculating the diffusivities of liquid-liquid systems has been proposed, and is used to obtain the diffusion coefficients for the above systems. A Ferranti Sirius computer is used to handle the calculations. The diffusion coefficients obtained in this investigation were examined in comparison with existing diffusional theories and semi-empirical equations. It is shown that these theories are inadequate, and it is also shown that the large deviations between the predicted diffusivities of the ethanolamines and the observed values are due, a) in part to the inadequacy of the equations, and b) In part to molecular irregularities of the ethanolamines in solution. By explaining the molecular irregularities of the ethanolamines in solution on the basis of a hydration effect, and calculating an approximate hydration number, a better agreement between the predicted and observed diffusivities obtained. In Part II of this work, the application of the wavefront shearing interferometer to gas-liquid diffusion is described. The gas cell built in this laboratory and the experimental technique is also described. Results for the systems CO2-water, and CO2 into dilute mono ethanolamine are reported. In the latter system, the presence of a reaction zone is experimentally illustrated, and calculations are made explaining the movement of this reaction zones It is believed that this is the first time ever that ever that a) the presence of this reaction zone has been shown experimentally, and b) that the movement of the zone has been plotted. At the moment, the application of this interferometer to gas-liquid diffusion is novel and needs improvement. When a fully successful experimental technique has been evolved, the possibilities for further work in this field are considerable.