carbon materials2 through their unique combination of excellent processability and high carbon yield. The enediyne functionality of the monomers undergo a thermal Bergman cycloaromatization reaction that yields reactive naphthalene diradicals which polymerize to form polynapthalene.(Figure 1) The tetrafunctionality of the monomers allows for both a higher processing window due to extensive branching and ultimately the formation of network polymers. The high carbon yield results in less shrinkage of the polymer upon pyrolysis to the glassy carbon state. This allows for the faithful templating of carbon structures from a polymeric precursor.

Hydrogen fuel cell electrodes require several properties for optimum performance. An ideal electrode would have as high a surface area as possible with an uniform dispersion of nano-scale catalyst particles attached to the surface. The electrode must be electrically conductive and have good mass transport for products and reactants. Carbon supported platinum is the best known catalyst for the oxidation of hydrogen at the anode and the reduction of oxygen at the cathode of a proton exchange membrane fuel cell (PEMFC) 3. The material also must have good compatibility with the material used for the proton exchange membrane in the membrane electrode assembly (MEA), usually a sulfonated fluoropolymer such as Nafion. We have undertaken a study to prepare a high surface area carbon material through a BODA templating method which can then be functionalized with both well dispersed platinum nanoparticles …

The effect of Aldrich humic acid (HA) on the mobility of {sup 137}Cs, {sup 85}Sr, {sup 152}Eu and {sup 239}Pu radionuclides was studied in Ca-montmorillonite suspensions. Verified 2-sites-2-species (2s2s) models correspond to an intensive interaction of all elements with humificated surface, what is in a remarkable contrast with the weak complexation of cesium and even strontium in solutions - the neutral ligand interaction constants {beta} (l/mol) are log {beta} < -9.9 and 7.56 {+-} 0.21 for Cs and Sr, respectively. The result for europium complexation in solution, log {beta} = 12.49 {+-} 0.18 is in a good agreement with literature data. For plutonium(IV) not only high proton competitive constant in solution was obtained, log {beta} = (-0.67 {+-} 0.32)+3pH, but also a strong chemisorption, which at high concentrations of humic acid (above 0.05 g/l) indicates the formation of bridge humate complexes of plutonium on the humificated surface. Logarithms of heterogeneous interaction constants ({beta}{sub 10}, l/g) of the elements with surface humic acid are 4.47 {+-} 0.23, 4.39 {+-} 0.08, and 6.40 {+-} 0.33 for Cs, Sr, and Eu(III), respectively, and the logarithm of the proton competitive constant ({beta}{sub 24}, l/g) for Pu(IV) -3.80 {+-}0.72. Distribution coefficients of humic acid and metal humates between 0.01 g HA/l solution and montmorillonite were derived as log K{sub d}(AH) = -1.04 {+-} 0.11, log K{sub d}(EuA) = 1.56 {+-} 0.11 and log K{sub d}(PuA) = 2.25 {+-} 0.04, while the values for Cs and Sr were obtained with very high uncertainty. Speciation of the elements on montmorillonite surface is illustrated as a function of equilibrium concentration of humic acid in solution and of pH.

Abstract

The high-performance size-exclusion chromatography (HPSEC) and radiochromatography (HPSERC) was used for the identification of radiocesium and radiostrontium interaction with humic acid. It was found that the behavior of humic acid on size-exclusion chromatography is sensitive to the salt concentration and pH of the mobile phase. At lower ionic strength and in acidic region of pH, the Aldrich humic acid exhibited three main fraction within the ranges > 760 kDa, 25-100 kDa and < 5 kDa. Radiocesium was found in the low-molecular fractions (< 1 kDa) of humic acids but radiostrontium interacts preferably with the fractions of humic acid of molecular weight within the range 2-5 kDa. (author) 27 refs.