Sulfonated poly(arylene ether sulfone)(SPAES) copolymer with degree of sulfonation of 1.0 was synthesized and characterized.A series of SPAES-TiO_2 hybrid membranes with various contents of nano-sized TiO_2 particles were prepared and characterized through sol-gel reactions.Scanning electron microscopy(SEM) images indicated the TiO_2 particles were well dispersed within polymer matrix.These composite membranes were evaluated for proton exchange membranes(PEMs) in direct methanol fuel cell(DMFC).These mem...
Chromium and/or arsenate removal by Fe(II) as a function of pH,Fe(II) dosage and initial Cr(VI)/As(V) ratio were examined in batch tests.The presence of arsenate reduced the removal efficiency of chromium by Fe(II),while the presence of chromate significantly increased the removal efficiency of arsenate by Fe(II) at pH 6-8.In the absence of arsenate,chromium removal by Fe(II) increased to a maximum with increasing pH from 4 to 7 and then decreased with a further increase in pH.The increment in Fe(II) dosage resulted in an improvement in chromium removal and the improvement was more remarkable under alkaline conditions than that under acidic conditions.Chromium removal by Fe(II) was reduced to a larger extent under neutral and alkaline conditions than that under acidic conditions due to the presence of 10 μmol/L arsenate.The presence of 20 μmol/L arsenate slightly improved chromium removal by Fe(II) at pH 3.9-5.8,but had detrimental effects at pH 6.7-9.8.Arsenate removal was improved significantly at pH 4-9 due to the presence of 10 μmol/L chromate at Fe(II) dosages of 20-60 μmol/L.Elevating the chromate concentration from 10 to 20 μmol/L resulted in a further improvement in arsenate removal at pH 4.0-4.6 when Fe(II) was dosed at 30-60 μmol/L.
A series of bi A-SPAES(Ds=0.4)/phosphotungstic acid(PWA/bi A-SPAES)composite membranes with various contents of PWA were prepared and characterized by FT-IR.Scanning electron microscopy(SEM)images indicated the PWA were well dispersed within polymer matrix.These composite membranes were evaluated for proton exchange membranes(PEM)in direct methanol fuel cell(DMFC).These membranes showed good thermal stability.It was found that the water uptake of these membranes increased with the increase of the PWA content in the hybrid membranes.Meanwhile,the introduction of inorganic particles increased both the proton conductivity and the methanol permeability.The proton conductivities of composite membranes were increased from 0.017 S/cm to 0.045 S/cm at 20 ℃ and from 0.054 S/cm to 0.093 S/cm at 100 ℃ with the increase of PWA content from 0 to 50 %.Especially,all the methanol diffusion coefficients(4.20×10-8-1.05×10-7cm2/s)of bi A-SPAES/PWA hybrid membranes are much lower than that of Nafion 117 membrane(2.1×10-6 cm2/s).Bi A-SPAES/PWA hybrid membranes were therefore proposed as candidates of material for PEM in DMFC.
