EFFECT OF DISSOLVED OXYGEN ON THE REDOX METHOD FOR THE MEASUREMENT OF MASS TRANSFER COEFFICIENTS A.
M. S U T E Y A N D J. G. K N U D S E N
Department of Chemical Engineering, Oregon State Uniaersity, Corvallis, Ore An electrochemical technique was used to measure average mass transfer coefficients at a solid-liquid interface. The effects of electrode length, flow rate, and the presence of air on the measured mass transfer coefficients were studied for a ferro-ferricyanide solution in turbulent flow in a smooth pipe, using a wire electrode mounted flush to the pipe wall, and a ring electrode which constituted a portion of the pipe wall. Experimental results compare well with heat and mass transfer data of other investigators. For the limited flow range ( N R ~ 22,000) and L/D ratios (LID 6 1.0) studied, the Leveque solution predicted coefficients to within =!= 8% of the experimental values. With certain precautions this technique can b e used to measure mass transfer coefficients in the presence of air. Coefficients measured with the '/*-inch electrode at oxygen saturations below 50% are within 3% of the correct value for an operating time of 170 minutes; those measured with the 1 -inch electrode are within 1.6% of the correct values for an operating time of 175 minutes.
