Potentiometric and amperometric measurements were made with microbial fuel cells containing E. coli or yeast as the anodic reducing agent and glucose as the oxidizable substrate. The catalytic effects of thionine and resorufin on the anode reaction were investigated. Results on the potentiometry, polarization, and coulombic output of the cells support a mediator-coupled mechanism for the transfer of electrons from the organism to the electrode in preference to a mechanism of "direct" electrochemical oxidation of glucose or its degradation products. Experiments with (14)C-labeled glucose show that when a microbial fuel cell produces a current under load, exogenous glucose is metabolized to produce (14)CO(2). The Coulombic yields of the cells indicate a high degree of energy conversion in these systems.

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Isobaric vapor-liquid equilibrium (VLE) measurements at atmospheric pressure were made for 1.0-3.0 m tetrapropylammonium bromide (TPAB) and 3.0 m tetrabutylammonium bromide (TBAB) in mixtures of 2-propanol and water, and 3.0 m TPAB and 3.0 m TBAB in mixtures of 1-propanol and water. In addition, VLE measurements were made on 3.0 m TBAB in 2-propanol + water mixtures at 0.080 bar. The effects of the salt on the VLE in each system were assessed via relative volatilities. The effect of the solute was to salt-out at high alcohol concentrations and salt-in at low alcohol concentrations. A vibratingtube densimeter was used to obtain solution densities at 25 °C from 0.1 to 4 m TBAB or TPAB in the pure solvent and in aqueous 1-propanol and 2-propanol solutions. Variations of the apparent molar volumes with salt molality in the mixed solvent differed markedly from those of the alcohol-free binary, while subtle distinctions were seen among the various salt and alcohol molecular structures.

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