Temperature extract differential

Extract temperature differential The increase or decrease in temperature between the supply air and the extract air. 

The Microwave-Assisted Process (MAP ) technology uses microwaves, and solvents that are relatively transparent to microwaves, to extract chemicals from various matrices based on the temperature differential between the solvent and the target compound. According to the developers, the technology is applicable to soils and wastes containing polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), total petroleum hydrocarbons (TPH), and other organic compounds. 

In the first one, the desorption rates and the corresponding desorbed amounts at a set of particular temperatures are extracted from the output data. These pairs of values are then substituted into the Arrhenius equation, and from their temperature dependence its parameters are estimated. This is the most general treatment, for which a more empirical knowledge of the time-temperature dependence is sufficient, and which in principle does not presume a constancy of the parameters in the Arrhenius equation. It requires, however, a graphical or numerical integration of experimental data and in some cases their differentiation as well, which inherently brings about some loss of information and accuracy, The reliability of the temperature estimate throughout the whole experiment with this... 

Solvent extraction carried out in conventional contactors like mixer-settlers and columns has certain limitations, including (a) controlling optimum dispersion and coalescence, (b) purifying both phases to ensure that stable emulsions are avoided (c) temperature control within a narrow band (d) high entrained solvent losses and related environmental and process economic effects and (e) large equipment dimensions and energy requirements when the density differential or selectivity is low. 

Because no pretreatment of the samples was carried out, the peaks present in the total ion current trace reflect components generated by pyrolysis of primary compounds ( real pyrolysis products ) and components that are present as such in the sample and simply evaporate ( free products ). If desired these two types of products may be differentiated using wires with a Curie temperature of 358°C [36], It was demonstrated in separate analyses (not shown here) that most compounds were not generated by pyrolysis but were present as such in the sample and thermally extracted . Compounds 1-8 and 10-17, 27, 37, 38, 54 and 65 were only present in pyrolysis gas... 

Extraction of 25 different binary mixtures of racemic acids (2-(4-isobutylphenyl)-propionic acid (1), and cis- and trans-chrysanthemic (2)), and various chiral bases with supercritical carbon dioxide permitted the conclusion that molecular chiral differentiation in a supercritical fluid is more efficient than in conventional solvents. In the majority of cases, however, complete separation could not be achieved. In five cases, remarkable partial resolutions were realized (30-75% ee) and resolution was possible on a preparative scale. The pair ds-chrysanthemic acid and (S)-(-i-)-2-(benzylamino)-1-butanol (3) was studied in detail. Pressure, temperature, and time, as well as the molar ratio of base and acid, had a marked influence on the quantity and quality of the products. Increasing pressure or decreasing temperature resulted in higher ee values. (-)-cw-Chrysanthemic acid in 99% ee was obtained from the raffinate in a single extraction step. Multiple extractions produced the (-i-)-cA-acid in 90% ee (see fig. 6.3) (Simandi et al., 1997). 

Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were performed simultaneously, using DTG-50 (Shimadzu), on the HMS samples after SFE. The mass loss between 150 to 300°C can be attributed to the decomposition and combustion of the amine template [3]. Hence, by expressing the mass loss of the samples in this temperature range as a percentage of the mass loss of the as-synthesised sample in the same temperature range, the extraction efficiency can be determined. 

The melting temperature (Tm) of the biopolymer was determined from differential scanning calorimetry thermograms. The Tm value of the P (3HB) homopolymer was about 177°C and P (3HB) with 10% P(3HV) was about 150°C (Table l),but the Tm values of biopolymer extracted from E. coli HMS174 were about 166°C. The Tm of the sample was lower than that of the P (3HB) homopolymer, but higher than that of the P (3HB) with 10% P (3HV), because the P (3HV) content in the sample is only about 4.5% of the biopolymer produced. The PHV content in extracted biopolymer was low, the flexibility of extracted biopolymer was low, and different fermentation conditions should be investigated. 

---