Abstract  A new application of capillary electrophoresis (CE) for measuring inorganic anions in hailstones was carried out. Five hailstone specimens were collected from large blocks of ice that fell in January 2000 in some provinces of Spain. Sample handling and preparation procedures were performed with care. CE analysis of anions was carried out using indirect UV detection at 254 nm with a negative power supply (-15 kV) and hydrostatic injection (10 cm for 30 s) at 35 degrees C. Anion separation was completed in less than 4 min. The working electrolyte consisted of 4.7 mM sodium chromate, 4.0 mM OFM-OH (tetradecyltrimethylammonium hydroxide), 10 mM CHES [2-(N-cyclohexylamino)ethanesulfonic acid], and 0.1 mM calcium gluconate (pH 9.1). Good repeatability of migration times after eight injections (<0.7% RSD), adequate linearity responses (r2>0.9) as well as satisfactory detection limits (<0.35 ppm) were achieved. The analytical results provided by CE were compared with those obtained by traditional wet-chemical (WCH) methods. Most of the results obtained by CE were consistent with those of WCH, except for one sample.

Abstract  A new application of capillary electrophoresis for measuring major and trace anions in thermal water and condensed-steam samples is presented. Ten fluid samples were collected from hydrothermal springs and fumaroles located in a volcanic zone of Deception Island, Antarctica. Anion separation was achieved in less than 6 min using indirect UV detection at 254 nm with a negative power supply (-15 kV). The electrolyte consisted of 4.7 mM sodium chromate, 4.0 mM electroosmotic flow modifier (OFM) hydroxide, 10 mM 2-(N-cyclohexylamino)ethanesulfonic acid and 0.1 mM calcium gluconate (pH 9.1). Major anions (Cl-, SO4(2), PO4H2+, and CO3H-) were measured using hydrostatic injection (10 cm for 30 s) at 25 degrees C. Trace amounts of anions (F-, Br-, and NO3-) were better determined by electromigration injection (4 kV, 10 s) at 15 degrees C. Good reproducibility of the migration times (<0.72% RSD), a satisfactory linear response and accuracy as well as acceptable detection limits were successfully obtained.

Abstract  The vinyl addition type copolymer poly(butoxymethylene norbornene-co-biphenyl oxyhexamethyleneoxymethylene norbornene) (P(BN/BphN)) was synthesized by using bis-(beta-ketonaphthylimino)nickel(II)/B(C6F5)(3) catalytic system. P(BN/BphN) was sulfonated to give sulfonated P(BN/BphN) (SP(BN/BphN)) with concentrated sulfuric acid (98%) as sulfonating agent in a component solvent. The ion exchange capacity (IEC), degree of sulfonation (DS), water uptake, and methanol permeability of the SP(BN/BphN)s were increased with the sulfonated time. The methanol permeability of the SP(BN/BphN) membranes was in the range of 1.8 x 10(-7) to 7.5 x 10(-7) cm(2)/s, which were lower than the value 1.3 x 10(-6) cm(2)/s of Nafion (R) 115. The proton conductivity of SP(BN/BphN) membranes increased with the increase of IEC values, temperature, and water uptake. Water uptake of the SP(BN/BphN) membranes was lower than that of Nafion (R) 115 and leads to low proton conduction. Microscopic phase separation occurred in SP(BN/BphN) membrane and domains containing sulfonic acid groups were investigated by SEM and TEM. SP(BN/BphN) membranes had good mechanical properties, high thermal stability, and excellent oxidative stability. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Abstract  Methanol electrooxidation in a 0.5 M sulfuric acid electrolyte containing 1.0 M CH3OH was studied on 30% Pt/carbon and 30% PtRu/carbon (Pt/Ru = 1:1) catalysts using X-ray absorption spectroscopy (XAS). Absorption by Pt and Ru was measured at constant photon energy in the near edge region during linear potential sweeps of 10-50 mV/s between 0.01 and 1.36 V vs rhe. The absorption results were used to follow Pt and Ru oxidation and reduction under transient conditions as well as to monitor Ru dissolution. Both catalysts exhibited higher activity for methanol oxidation at high potential following multiple potential cycles. Correlation of XAS data with the potential sweeps indicates that Pt catalysts lose activity at high potentials due to Pt oxidation. The addition of Ru to Pt accelerates the rate of methanol oxidation at all potentials. Ru is more readily oxidized than Pt, but unlike Pt, its oxidation does not result in a decrease in catalytic activity. PtRu/carbon catalysts underwent significant changes during potential cycling due to Ru loss. Similar current density vs potential results were obtained using the same PtRu/carbon catalyst at the same loading in a membrane electrode assembly half cell with only a Nafion (DuPont) solid electrolyte. The results are interpreted in terms of a bifunctional catalyst mechanism in which Pt surface sites serve to chemisorb and dissociate methanol to protons and carbon monoxide, while Ru surface sites activate water and accelerate the oxidation of the chemisorbed CO intermediate. PtRu/carbon catalysts maintain their activity at very high potentials, which is attributed to the ability of the added Ru to keep Pt present in a reduced state, a necessary requirement for methanol chemisorption and dissociation.

Abstract  Direct methanol fuel cell operation with uniaxially pre-stretched recast Nafion[super][registered] membranes (draw ratio of 4) was investigated and compared to that with commercial (un-stretched) Nafion[super][registered]. The effects of membrane thickness (60-250 [micro]m) and methanol feed concentration (0.5-10.0 M) on fuel cell power output were quantified for a cell temperature of 60 [deg]C, ambient pressure air, and anode/cathode catalyst loadings of 4.0 mg cm[super]-2. Pre-stretched recast Nafion[super][registered] in the 130-180 [micro]m thickness range produced the highest power at 0.4 V (84 mW cm[super]-2), as compared to 58 mW cm[super]-2 for Nafion[super][registered] 117. MEAs with pre-stretched recast Nafion[super][registered] consistently out-performed Nafion[super][registered] 117 at all methanol feed concentrations, with 33-48% higher power densities at 0.4 V, due to a combination of low area-specific resistance (the use of a thinner pre-stretched membrane, where the conductivity was the same as that for commercial Nafion[super][registered]) and low methanol crossover (due to low methanol solubility in the membrane). Very high power was generated with a 180-[micro]m thick pre-stretched recast Nafion[super][registered] membrane by increasing the cell temperature to 80 [deg]C, increasing the anode/cathode catalyst loading to 8.0 mg cm[super]-2, and increasing the cathode air pressure to 25 psig. Under these conditions the power density at 0.4 V for a 1.0-M methanol feed solution was 240 mW cm[super]-2 and the maximum power density was 252 mW cm[super]-2.

Abstract  Catalyst-coated membranes (CCMs) play an important role in the PEMFCs. The direct-spraying deposition method that is using ethyleneglycol (EG) soaked Nafion membrane and the catalyst ink with isopropyl alcohol as the primary liquid media and small amount of EG as additive has been developed for fabrication of high-quality CCMs. The properties of the CCMs have been analyzed by SEM, I-V and EIS characterization. Both modification of catalyst layers and membrane surfaces with Nafion had significant impacts on the cell performance. On favorable conditions, a peak power density of similar to 430mW/cm(2) could be achieved for a H-2 vertical bar O-2 cell at ambient pressure and total Pt loading of 0.3mg/cm(2) including both the anode and cathode. (C) 2008 Elsevier B.V. All rights reserved.