CO2 treatment

Figure 15.19 (a) Schematic preparation procedure and apparatus for Rh and PtRh nanoparticle catalysts from Rh and PtRh salt-impregnated silicates by super critical fluid CO2 treatment (b) phase diagram of super critical CO2 as functions of pressure and temperature. 

Storage conditions and preservation treatments also can affect the free amino acid content. Some authors [242] reported changes in the concentration of free amino acids of broccoli florets stored in air or in controlled atmospheres. Arginine concentration varied greatly during air storage, while y-amino butyric acid, alanine and an unidentified amino acid accumulated in response to low O2 and/or high CO2 treatment. 

In high-pressure applications these are two main trends of research high hydrostatic pressure treatment (2000-7000 bar) and supercritical CO2 treatment. In both cases the aim is to inactivate the micro-organisms in order to protect and preserve foods, and so to prolong their shelf-life. 

In the following pages, we describe some experiments run in our High Pressure laboratory, in order to show how CO2 treatment technology can be applied to micro-organisms of interest for the agro-alimentary industry. 

When the CO2 treatment was finished, residual viable micro-organisms were counted according to plate standard procedures (for solid media and conditions see Table 9.10-1). The cultures were suspended in PBS buffer and diluted to reach about 107 colony-forming units, CFU/ml, for bacteria and 105 CFU/ml for yeast. 

Results obtained for CO2 treatment seem to be particularly attractive for the development of industrial applications so far, mainly experiments on microbial suspensions have been carried out, and they are really successful. However, some questions remain as to the behaviour of micro-organisms in complex substrates, as it is well known that they are more resistant than in buffered solutions [32], Another issue to be addressed in this case is the simultaneous effect of CO2 as an extracting agent, as it could interfere with the quality of the final product. 

After the pore-size was established, the membranes were treated in a steel reactor with a Simulated Ambient Steam Reforming Atmosphere (SASRA) for 100 hrs at 600°C with H2O/CH4 = 3/1 (by volume) at 2.5 MPa total pressure. Heating and cooling was performed in an argon atmosphere at the same total pressure at a rate of 1 °C/min. In a few experiments a pure steam treatment was carried out at 0.2 MPa total pressure at 150°C or 300°C in the same manner as for SASRA treatment. A pure CO2 treatment was done likewise, but at 500°C at 1.2 MPa pressure. 

The effect of CO2 on the stability of the membranes was tested, because of the possible instability of lanthanum compounds towards CO2 (formation of La2(CC>3)2). CO2 treatment at 600°C for 100 hours did not result in a measurable pore-growth the pore-size increased from 6.0 nm to 6.3 nm after treatment, which is within the measurement error. 

Schuetze, S. M. and Goodenough, D. A. (1982). Dye transfer between cells of the embryonic chick lens becomes less sensitive to CO2 treatment with development. J. Cell Biol. 92, 694-705. 

NANOPOROUS PLASMA-ENHANCED eVD FILMS VIA ANNEALING AND SUPERCRITICAL CO2 TREATMENTS... 

The compositional differences in treated and untreated samples of Pittsburgh Seam coal are presented in Table II. The 80 C, 1200 psi CO2 treatment afforded a decrease in ash content and volatile matter. A significant decrease in sulfur was also observed. The small change in heating value supports the belief that this process does not drastically alter the coal structure. 

On treatment with CO2 organohthium compounds can be converted to the corresponding lithium carboxylates. The high efficiency and operational simplicity of this reaction make it a general route for carboxylic acid synthesis [83-86] (Scheme 1.38). For example, opticaUy active carboxylic acids are accessible by deprotonation followed by the subsequent CO2 treatment in the presence of 10 [85] (Scheme 1.39). 

Fig. 4. Concentration before and after CO2 treatment. Solid symbols are pretreatment concentrations. Open symbols are post-treatment concentrations through time, (a) Crooks Gap calcium and magnesium, (b) Bonanza calcium and magnesium, (c) Grass Creek calcium and magnesium, (d) Cole Creek calcium and magnesium, (e) North Grieve calcium and magnesium, (f) Beaver Creek total dissolved solids. Note the different x-axis scale for North Grieve.

Fig. 10. Concentrations of silica and aluminium before and after CO2 treatments at (a) Crooks Gap and (b) Bonanza. Closed symbols are pre-C02. Open symbols are post-C02 concentrations through time.

The potential for well-bore scale during these CO2 treatments is determined by first predicting how much carbonate mineral dissolution will take place. After a calcite saturation index has been calculated for a water analysis for both pre- and post-C02 treatment, then Fig. 7 can be used to determine how much calcium (and therefore bicarbonate) will have been added to treated waters from calcite dissolution. These calcium and bicarbonate values can be added to the original formation water, which is then used to calculate a new calcite saturation index for the new water. 

This was done for Crooks Gap using nine sets of calculations at different pressures to represent the declining pressure conditions up the production tubing to surface lines. The results are shown in Fig. 11, which is a plot of Sl ajc vs depth. Even with extra calcium in the water from calcite dissolution, the water in the subsurface production tubing remains undersaturated with respect to calcium carbonate, and therefore scale would not be expected to precipitate. After 230 days of production the downhole pump at Crooks Gap was retrieved in preparation for another CO2 treatment, and indeed no scale was observed on the pump. 

Fig. 13. CO2 gas saturation vs distance from the injection well bore for a simulated cyclic CO2 treatment on a homogeneous reservoir. After Hsu Brugman (1986).

Permeability enhancement is not the mechanism of enhancing oil recovery in these cyclic CO2 treatments, with the possible exception of cleaning up scale that might have been clogging perforations. 

The reaction product from CO2 treatment on single distillation gives triethanolamine of 89.8 per cent purity. Without COj, the purity is only 39 per-cent. ... 

Heating the 2,4,6-trisubstituted-l,2,3,5-oxathiadiazine 2-oxide 111 (X = Cl, NR2 = piperidino or pyrrolidine) at 60 °C in benzene, toluene, or chloroform with an equimolar amount of water resulted in conversion to the salts 26 (Scheme 10). This process apparently involves initial hydrolysis of the trichloroacetamide fragment followed by an unusual substitution of the piperidino or pyrrolidino moiety by the CCI3 group with concomitant loss of CO2. Treatment of salts 26 with sulfuric acid affords the 1,2,4,6-thiatriazine 1,1-dioxide 112 which revert to salts 26 with piperidine or pyrrolidine <2002RJ01702>. 

Nonpyrophoric Ni Catalyst by CO2 Treatment 1961 - Ni Catalyst from Powdered Ni and Ni-Al Alloy... 

The crystallite size decreases with decreasing treatment temperature. It is suggested that the CO2 treatment promotes the creation of nuclei in the amorphous state at low temperatures, followed by the formation of fine crystallites. 

Adult male C57 BL/6 mice, obtained from B K, Sollentuna, Sweden, were used throughout this study. Mice were maintained on a standard chow diet before commencement of the experiments. Mice were fed a fat-free diet (FF), a 0.5% (w/w) clofi-brate-containing diet (Clo) or fasted as indicated. All mice had access to water ad libitum. The animals were sacrificed by CO2 treatment followed by cervical dislocation, and weighed immediately. The various tissues were then excised, weighed and frozen in liquid nitrogen. 

Dreux et al. studied the effect of CF4 and CO2 plasma treatment on the barrier properties of polyamide 12 (PA12, ATOFINA, Serquigny, France) toward permeant molecules of opposing characters, i.e., water and toluene [44]. While CF4 treatment made the surface more hydrophobic, CO2 treatment made it more hydrophilic. The surfaces were studied by AFM and XPS. 

The CF4 plasma treatment led to a decrease in the permeability of both water and toluene. With the CO2 treatment, on the other hand, water permeability increased and toluene permeability decreased. Figure 4.24 shows the AFM image of the untreated PA12 surface for different scan sizes. Figures 4.25 and 4.26 show the AFM images of CF4 and CO2 plasma-treated PA12 membranes, respectively. Obviously, the surface changed after plasma treatments. A denser layer was formed by the plasma treatment. 

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