Oxygen Solubility in Industrial Process Development

Industrial & Engineering Chemistry Research - IND ENG CHEM RES 03/2003; 42(8). DOI: 10.1021/ie020990s

ABSTRACT Oxygen solubility in pure water and in dilute sulfuric acid solution has been studied as a part of atmospheric direct zinc leaching process development. The experimental results were compared with reference data and the Gibbs energy model. The dissolution dynamics of oxygen was further combined with the Gibbs energy minimization method. Together the experimental and model results give useful information and methodology for the developers of industrial processes related to gas solubility. The dynamic Gibbs energy calculation approach presented in this work extends the possibilities of evaluating changes in different process chemistries needed in process design.

  • [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate a planar direct methanol fuel cell by integrating a 200 mum-wide Nafion strip in a polydimethylsiloxane (PDMS) structure. The design is based on two 200 mum-wide parallel microfluidic channels, sandwiching the Nafion strip. We mechanically clamp the PDMS/ Nafion assembly with a catalyst-covered glass chip and use 1 M CH3OH/ 0.5 M H2SO4 as fuel in the anodic channel and O2-saturated 0.5 M H2SO4 as oxidant solution in the cathodic channel. The fuel cell has a stable maximum power density of 0.52 mW/cm2 at room temperature with fuel and oxidant flow rates in the 20-160 muL/min range.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Several modifications of manganese dioxide (MnO 2 ) were investigated for use in composite electrode materials for oxygen evolution, the target application being anodes for the industrial electrowinning of metals. It is demonstrated that the performance of this material depends strongly on the modifications of MnO 2 . All modifications investigated were found to be more active than the usual anode of lead alloyed with silver (PbAg) used in zinc electrowinning. A composite sample containing chemical manganese dioxide (CMD) was found to give an oxygen evolution overpotential 0.25 V lower than the standard PbAg anode material. In the second part of the article, we investigate the effect of varying several parameters of the composite electrode assembly, including the size of the catalyst particles and percentage of the catalyst material used. A model is proposed where the performance of the material is proportional to the total length of the boundaries between the lead matrix material and the MnO 2 catalyst particles. Physicochemical processes contributing to the observed data are discussed.
    Journal of Applied Electrochemistry 01/2009; 39:1835-1848. · 1.84 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate a monolithic polymer electrolyte membrane fuel cell by integrating a narrow (200μm) Nafion strip in a molded polydimethylsiloxane (PDMS) structure. We propose two designs, based on two 200μm-wide and two 80μm-wide parallel microfluidic channels, sandwiching the Nafion strip, respectively. Clamping the PDMS/Nafion assembly with a glass chip that has catalyst-covered Au electrodes, results in a leak-tight fuel cell with stable electrical output. Using 1M CH3OH in 0.5M H2SO4 solution as fuel in the anodic channel, we compare the performance of (I) O2-saturated 0.5M H2SO4 and (II) 0.01M H2O2 in 0.5M H2SO4 oxidant solutions in the cathodic channel. For the 200μm channel width, the fuel cell has a maximum power density of 0.5mWcm−2 and 1.5mWcm−2 at room temperature, for oxidants I and II, respectively, with fuel and oxidant flow rates in the 50–160μLmin−1 range. A maximum power density of 3.0mWcm−2 is obtained, using oxidant II for the chip with 80μm-wide channel, due to an improved design that reduces oxidant and fuel depletion effects near the electrodes.
    Journal of Power Sources 01/2009; 193(2):761-765. · 4.68 Impact Factor