Zhang Ping-min

UV-Vis spectra of polyaniline doped with camphor sulfonic acid in different organic solvents

The doping reaction of polyaniline with camphor sulfonic acid (CSAH) in different organic solvents was studied by UV-Vis spectroscopy. The experimental results show that the polaron band of the species was shifted to shorter wavelength when polyaniline was doped with CSAH in N-methyl-2-pyrrolidione (NMP) solvent, while the red shift of polaron band was observed when it was in N, N-dimethylformamide (DMF). It indicates that the influence of different processing solvents on the doping property of polyaniline is greatly different. N-methyl-2-pyrrolidione is a good solvent for polyaniline, polyaniline chain is unfolded in it. The interaction of NMP with CSAH is so strong that the resulting product is apt to dedoping, while the solubility of polyaniline in DMF is relatively low and polyaniline chain is in partly folded state. Thus the doping reaction is kinetically disadvantageous but thermodynamically advantageous.

A New Approach to the Electrochemical Decomposition of Aqueous Hydrogen Sulfide Solution into Sulfur and Hydrogen Gas

A new approach to the electrochemical decomposition of aqueous hydrogen sulfide solution into elemental sulfur and hydrogen gas has been proposed; this approach can be used to get rid of anode passivation caused by sulfur precipitated on the anode surface. After all sulfides, including S 2– , HS – and H2S in the anodic compartment, have been mostly converted into polysulfide ions, hydrogen sulfide gas is bubbled through the anolyte until the pH of the solution remains approximately constant. Sulfur is removed from the reaction mixture, which is then returned to the anode compartment where the unreacted sulfides and undecomposed lower polysulfide ions continue to undergo electrolysis into polysulfide ions, and then their decomposition by H2S gas again takes place. This cyclic process will lead to a high current efficiency with which aqueous H2S is electrochemically decomposed into sulfur and hydrogen gas without anode passivation. Results of both equilibrium calculations and experiments show the viability of this new approach.

Enthalpies of formation of some phases present in the Y-Ba-Cu-O system by solution calorimetry

Enthalpies of some of the phases in the Y−Ba−Cu−O system were determined by solution calorimetry using a Calvet microcalorimeter. The standard enthalpies of formation for the phases were found to be YBa2Cu3O6.60, −2627.9; YBa2Cu3O6.77, −2641.8; YBa2Cu3O6.90, −2652.0; YBa2Cu3O6.99, −2659.3; Y2Cu2O5, −2198.6; Y2BaCuO5, −2656.4; BaCuO2.33, −788.6; and BaCuO2.42, −796.2 kJ-mol−1.

Separation and Determination of Sulfur with Different Valance in Polysulfide Mixture

A new process of separating sulfur with different valance from polysulfide mixtures was developed. Sulfide, sulfite and sulfur were separated by adding acetic acid in one step. The polysulfide mixture, sulfite solution and sulfur were oxidized to sulfate by hydrogen peroxide. The products were measured by X-ray Fluorescence Spectrometer(XRF) using filter method preparative specimen. The measurement needs only one set of standard sample. The effects of temperature and pH values on the separation were discussed. The results show that the recoveries range from 98.0% to 101.3% of sulfidic sulfur S(-II), 97.0% to 103.0% for sulfite S(IV) and 98.4% to 100.4% for polysulfidic sulfur S(0).