Highly charged polymers

Pu(IV), which forms highly charged polymers, strongly sorbs to soils and sediments. Other actinide III and IV oxidation states also bind by ion exchange to clays. The uptake of these species by solids is in the same sequence as the order of hydrolysis Pu > Am(III) > U(VI) > Np(V). The uptake of these actinides by plants appears to be in the reverse order of hydrolysis Np(V) > U(VI) > Am(III) > Pu(IV), with plants showing little ability to assimilate the immobile hydrolyzed species. The further concentration of these species in the food chain with subsequent deposit in humans appears to be minor. Of the 4 tons of plutonium released to the environment in atmospheric testing of nuclear weapons, the total amount fixed in the world population is less than 1 g [of this amount, most (99.9%) was inhaled rather than ingested]. 

The third possibility is most consistent with these data and is consistent with previous observations tiiat this linkage is only electrochemically reversible in aqueous solutions 19). For poly-3, Ae data are more consistent with process 2 for the first set of two le" oxidations. For the next 2e" process, the mass gain is most consistent with incorporation two PFe" and some solvent. Upon rereduction the mass loss is kineticdly slow. Not until the reduction at -0.7 V does the mass return to zero. The more highly charged polymers such as [poly-3] mig t be expected to need solvent to stabilize the concentrated... 

A,p is the Debye-Hiickel parameter (at 298.2 K 0.3914), / is the ionic strength (on molality scale), and h is a numerical value (h = 1.2). This expression is very well suited to describe the activity coefficient of ions at high dilutions, but cannot directly be applied to polyelectrolyte solutions because the Debye-Hiickel term was developed for punctual electric charges (such as small mobile ions). It is not valid for highly charged polymer backbones. Pessoa and Maurer [110] replaced the contribution of the polyion in the expression for the ionic strength ... 

However, contrary to other polyelectrolyte-surfactant systems [39-42], the precipitate does not redissolve with an excess of surfactant, at least in the examined, very broad, interval of concentrations. The difficulty of the redissolution of complexes composed of very highly charged polymers has also been observed in some other studies [41, 43, 44]. 

A correct value of the molecular weight is obtained for the charged polymer by the van t Hoff equation, provided that a large excess of indifferent electrolyte is present. These high concentrations are described as swamping electrolyte conditions. 

Catalysts in this service can deactivate by several different mechanisms, but deactivation is ordinarily and primarily the result of deposition of carbonaceous materials onto the catalyst surface during hydrocarbon charge-stock processing at elevated temperature. This deposit of highly dehydrogenated polymers or polynuclear-condensed ring aromatics is called coke. The deposition of coke on the catalyst results in substantial deterioration in catalyst performance. The catalyst activity, or its abiUty to convert reactants, is adversely affected by this coke deposition, and the catalyst is referred to as spent. The coke deposits on spent reforming catalyst may exceed 20 wt %. 

S-Poly(L-malic acid) ionizes readily in water giving rise to a highly soluble polyanion. Thus, a 2% solution of the free acid of the polymer from Aureobasidium sp. A-91 showed a pH 2.0 [5]. The ionic constants have been determined to be pKa = 3.6 for the polymer from Aureo-basidumsp. A-9 [5] and pKa (25°C) = 3.45 for/3-poly(L-malic acid) of Mw 24 kDa from F. polycephalum (Valussi and Cesaro, unpublished results) Thus, the polymer is highly charged under physiological conditions (pH 7.0). 

A conjugated polymer of a high charge carrier concentration (n> 1017 cm-3) arranged between two mclal electrodes, can be understood as a MSM structure [40. ... 

In a first approximation, conjugated polymers with a high charge earner concentration can be described as p-lype semiconductors whereby holes seem to be the majority charge earners. Depending on the workfunction of the polymer rela-... 

Color in water (apart from textile dyes, etc.) often is caused by the degradation of natural organic matter, resulting in colloidal humic and fiilvic acids. These are best removed by precipitation with metal salts, but performance may be improved with high-charge cationic polymers. 

Capillary gel electrophoresis is becoming very widely used in the biotechnology field for the high resolution separation of DNA and peptides according to molecular weight, but it has limited application for the analysis of surfactants (Wallingford, 1996). CGE does result in an increase in the resolution per unit time over SEC for charged polymers (Poli and Schure,1992). 

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