ELECTRODE DETERMINATION OF OXYGEN SOLUBILITY AND DIFFUSIVITY IN SOLUTION
Abstract
Procedures and experimental requisites were developed for application of microcomputer assisted chronoamperometry at an unshielded Pt disc electrode for simultaneous measurement of dissolved oxygen solubility and diffusivity in aqueous solutions. Time scale of the chronoamperometry was ca. 8 sec. It was found that alkaline solution and cathodic electrode pretreatment were desirable conditions for successful application of the procedure. Best results were obtained when an oxygen reduction system was used for electrode area and perimeter calibration, provided that similar time scales were used for calibration and experimental chronoamperometry. The method was employed to measure the effect of saccharides on dissolved oxygen solubility and diffusivity. Solutions of a monosaccharide (1-O-methyl-(alpha)-D-glucopyranoside), a disaccharide (sucrose), a trisaccharide (raffinose), and a polysaccharide (xanthan gum, MW > 10('6)) were studied. Oxygen solubility was observed to decrease in direct proportion to carbohydrate concentration for the simple saccharide solutions. The proportionality constant increased with chain length. Solubility was not effected in the low concentration xanthan gum solutions. The lowest oxygen solubility observed was 36% of the pure water value in 2.0 M sucrose solution. Measured oxygen diffusivity in the simple carbohydrate solutions were all below the pure water value. Log of diffusivity could be correlated with log of solution viscosity. The same correlation appeared to be valid for each simple carbohydrate. Diffusivity was uneffected in the highly viscous, non-Newtonian xanthan gum solutions (0.03 wt%, 0.06 wt%). The lowest observed oxygen diffusivity was 16% of the pure water value in 2.0 M sucrose solution.
Degree
Ph.D.
Subject Area
Chemical engineering
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.