Degradation experimental systems

Biological. Under aerobic conditions or in experimental systems containing mixed cultures, hexachloroethane was reported to degrade to tetrachloroethane (Vogel et al, 1987). In an uninhibited anoxic-sediment water suspension, hexachloroethane degraded to tetrachloroethylene. The reported half-life for this transformation was 19.7 min (Jafvert and Wolfe, 1987). When hexachloroethane (5 and 10 mg/L) was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum for 7 d, 100% biodegradation with rapid adaptation was observed (Tabak et al, 1981). 

The photocatalytic-induced hydrolysis implies that, in stoichiometric reactions, every water molecule corresponds to concurrent reactions with OH/c / H + (in any order) and that the ratio of reaction stoichiometric coefficients has to be equal to that between the concentrations of products found in the experimental system. This conceptual frame was demonstrated to be useful for understanding complex degradation pathways of organic molecules. 

Because nitrobenzene degradation is faster in batch experimental systems than in column studies, a mass-transfer limitation exists therefore, when determining the effectiveness of in situ groundwater treatment systems, hydraulics, mass transfer, and reaction kinetics should be taken into consideration (Burris et al., 1996). 

Arnosti, C., and D. J. Repeta. 1994b. Oligosaccharide degradation by anaerobic marine bacteria Characterization of an experimental system to study polymer degradation in sediments. Limnology and Oceanography 39 1865-1877. 

Ira the same experimental system, but one in which anaerobic conditions were established by replacing air with nitrogen gas throughout the incubation period, negligible degradation of PBO took place (Mayo, 1995a). 

The concentration dependence of rig conqjuted from Equation 20 Is shown In Fig. 30, where the solid points represent the experimental data and the open points their values corrected for the effects of PP degradation. For System-1 there Is strong negative deviation (NDB) from the log additivity rule, viz. Equation 1, but for System-2 NDB Is visible at low PP content, converting to positive deviation (PDB) at high. It Is worth recalling that ng was computed from corrected for the yield stress values of n. The NDB behavior. Indicative of Interlayer slip, reflects poor miscibility In System-1 and that at low concentration of PP In System-2. The emulslon-llke behavior of Syetem-2 at high PP content reflects a better Interphase Interaction. 

The photocatalytic degradation of phenol over Ti02 can be carried out in Photo-CREC-Water-H reactor. The experimental system and the experimental methods used are explained in Chapters II and III. 

Phosphorylase has a relatively low rate of turnover, and as such, large doses of radiolabeled pyridoxine were needed to obtain an adequate degree of labeling. In addition, the need for serial sampling of the decay curve, using individual animals, introduced substantial biological variation. Both aspects of this experimental system precluded application of the method to humans, and we considered the possibility of a different approach, based on stable-isotope-labeled pyridoxine, to monitor phosphorylase degradation. 

Thus a short-Uving (ca. 1 ps) alkoxy type macroradical was only present in our experimental system. This macroradical was extremely unstable and degraded quickly to fragments with lower molar mass (compare Scheme 1). 

Another experiment was conducted (Reed 1990 Reed and Hajash 1992) using only unbuffered 0.01 M oxalic acid (no solid) to monitor potential reaction with the experimental system and/or thermal degradation of the oxalate. In this experiment, which ran for s30 days at 100°C and 345 bar, oxalate in the reacted solution remained near initial values and was apparently not removed by reaction with the system, precipitation, or decarboxylation. The pHf was also essentially constant at 2.1. Reaction with the experimental system was limited to minor leaching of Fe (<7 ppm) and Ni (<10ppm). Ti was below detection limits (<2ppm). 

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