No abstract

Dialkyltetralin sulfonate (DATS) and single methyl-branched isomers of linear alkylbenzene sulfonate (iso-LAS) are coproducts that together can range from 1 to 10% of commercial LAS depending on the manufacturing process. Biodegradation studies using radiolabeled DATS and iso-LAS showed mineralization by indigenous microbial populations in laboratory simulations of aquatic and soil environments. Half-lives ranged from 2 to 20 days, which is rapid enough to suggest that accumulation would not occur in these environments. Upon exposure to laboratory activated sludge treatment, most model iso-LAS compounds showed greater than 98% parent compound removal, extensive mineralization (>50%), and 79-90% ultimate biodegradation (mineralization plus conversion to biomass). Activated sludge treatment of DATS and one of the iso-LAS isomers (methyl group attached to the benzylic carbon of the alkyl chain) resulted in >98% removal, 3-12% ultimate biodegradation and apparent formation of carboxylated biodegradation intermediates that accounted for 88-97% of the original material. These DATS and iso-LAS biodegradation intermediates continued to mineralize in simulated receiving water and soil environments at rates similar to that of sulfophenyl carboxylate (SPC) intermediates of a standard LAS.

There are five carbon atoms in this molecule, so Nc = 5. By use of eq 4, the upper flammability limit is estimated to be 11.4 vol %. Sax (1984) reported an experimental value of 9.0 vol %.

The angular distribution parameter, /?, has been measured for the resonant Auger spectra in Kr following 3d--Sp excitation. Unusually low values, close to -1, were seen for two bands. From optical spectroscopy data these bands are assigned to the final states 4p 4 ( 3 P)5p( 4 Ps/2, V3/2, and 4 D^/i). According to angular-momentum transfer theory, some of the transitions could be parity unfavored, yielding p values of -1, but additional theory is required for complete understanding. Implications for angular studies of highly resolved Auger spectra are discussed.

We report the x-ray absorption spectra for two hard carbon films grown by filament-assisted chemical vapor deposition in gas mixtures of 1% and 0.18% methane in hydrogen. Although the Raman spectra of these two films suggest significant differences in structure, the x-ray absorption near-edge structure and extended x-ray absorption fine structure (EXAFS) are very similar. Analyzing the EXAFS from these films with a diamond crystal as a reference gives carboncarbon bond lengths of 1.53±0.03 Å. This result is consistent with diamond and incompatible with graphite. We conclude that the carbon films have the same local structure as diamond.