Solvent Absorption Process Research Articles

The swelling behavior of interpenetrating polymer networks composed of polyurethane and unsaturated polyester

AbstractThe kinetics of swelling and the sorption performance were observed for the polymer compositions with interpenetrating polymer networks made up of polyurethane and unsaturated polyester during their exposure to chlorobenzene at 25°C. It was found that the rates for solvent transport and solvent absorption processes were controlled by the chemical composition of the formulation studied. On the basis of the observed swelling process, parameters could be assessed which were specific for the mass transfer process, i.e., diffusion coefficient, sorption coefficient, and permeability coefficient. Moreover, an attempt was made to evaluate structural parameters that describe topology of the obtained networks. It was found that the increasing share of polyurethane in the composition reduced crosslinking density in the polyester network that resulted in faster diffusion of the solvent and higher sorption capacity for the solvent. The higher the styrene content in the composition, the higher the crosslinking density in the system, and hence the diffusion of solvent and its sorption inside the polymer network was much more difficult. In the scanning electron microscope analysis of samples, which had been subjected to swelling, no leaching was observed for any phase present in the system, despite phase separation for both the components. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3511–3519, 2006

Numerical method to evaluate the influence of organic solvent absorption on the conductivity of polymeric composites

A theoretical analysis that describes the change in electric properties of polymeric composites, filled with conductive aggregates, during organic solvent absorption processes is presented in this work. This methodology takes into account the moving boundaries typical of this phenomena; requiring simple numerical procedures to be solved. The results show no numerical instabilities during the calculation process. The obtained results correlate very close to the available experimental data; therefore could be very useful for chemical sensor design.

Solvatochromic betaine dyes as optochemical sensor materials: detection of polar and non-polar vapors

Solvatochromic effects in the UV/VIS spectra of dyes can be applied to the monitoring of solvents in the gaseous phase. Within the class of solvatochromic dyes Reichhardt's betaine reveals an outstanding hypsochromic effect on protic solvents with a band shift of up to 350 nm. For vapor detection, the sensor behavior was optimized according to the linearity of the response signal, the sensitivity and a minimum influence of humidity by hydrophobizing siloxanes as additives. Furthermore, the dyes were immobilized under mild conditions by a sol–gel process which generates a high porosity for easy analyte access. The detection principle could be further extended to aprotic, polar solvents by embedding the dyes in protic matrices that form hydrogen bonds to the betaine oxygen. Then, the analyte disturbs the hydrogen bonds resulting in a bathochromic band shift resembling a back titration. Finally, the betaine phenol blue even allows the detection of halogenated hydrocarbons that lack a pronounced functionality but nonetheless a hyperchromic effect occurs during analyte exposition. Mechanistic aspects of these solvent absorption processes were traced by mass-sensitive measurements.

Radiation Damage of Fluorocarbon by Krypton-85 Beta-Rays, (II)

Ampoule irradiations using 60Co γ-rays were undertaken on CC12F2, C2C14F2 and C2C13F3 to gain information concerning the radiation damage of fluorocarbon, used as solvent in the recovery of 85Kr from the off-gas of fuel reprocessing plants operating on the solvent absorption process. The dose rate was varied in the range of 2.6×104~8.0×105 rad/h and the irradiation temperature in the range of −100~70°C. Identified among the numerous degradation products were six compounds deriving from CC12F2, eleven from C2C14F2, and eleven also from C2C13F3. The decomposition yield of each of these fluorocarbons increased with irradiation temperature, and decreased with dose rate. It rose roughly in proportion to the absorbed dose. Comparison of decomposition behavior between the four fluorocarbons (including CC13F covered in the preceding report) was made in reference to the irradiation temperatures corresponding to those at which these fluorocarbons would respectively be applied in practice as solvent for 85Kr absorpt...

A Selective Solvent for Purifying Natural Gas

Bench experiments and laboratory field pilot plant testing have led to the development of a solvent that is selective in removing CO and H S from natural gas at pipeline pressure. The acid gases are physically absorbed in the solvent and no chemical reaction takes place. Introduction A few years ago, most commercial acid-gas removal processes involved the use of either amines or processes involved the use of either amines or potassium carbonate solutions. These materials chemically potassium carbonate solutions. These materials chemically react with hydrogen sulfide and carbon dioxide, giving off appreciable quantities of heat. Heat must be supplied to regenerate the solutions. In recent years, several companies have developed selective solvents to remove acid gases from natural gas and synthesis gas. The selective solvents operate on the principle of pure physical absorption, as one would calculate using vapor-liquid equilibrium ratios (K-values) for the appropriate systems. Since there is a heat of absorption and desorption involved, the heat effects are much smaller than with solutions involving chemical reactions, and the selective solvent can be regenerated without reboiling. Solvent absorption is especially useful in cases where the partial pressure of the acid gas exceeds 150 psia, and preferably 200 psia. The cost advantage of the solvent absorption psia. The cost advantage of the solvent absorption process arises largely from the saving of heat process arises largely from the saving of heat ordinarily used in the regeneration of amines and hot potassium carbonate solutions, which is substantial potassium carbonate solutions, which is substantial when large volumes of acid gas are involved. Preliminary Screening Tests Preliminary Screening Tests Several years ago, we made a detailed study of acid gas processing that led to the discovery of some 11 classes of polar, organic solvents that were effective in removing acid gas. Solubilities of CO and propane were measured in a large number of solvents at 1 atm and about 80 deg. F. Results of these measurements revealed the solvents covered by Union Oil Co. patents. Solubility data related to these solvents and patents. Solubility data related to these solvents and competitive solvents are shown in Table 1. The solubility ratio of CO to propane is a measure of the selectivity of the solvent. A high selectivity is obviously desirable. Some H S solubility data have been included. Table 2 lists properties of these relatively nonvolatile selective solvents. Results from a bench scale pilot plant narrowed the number of solvents of chief interest, and pointed to the need for a field pilot plant for further study. In the fall of 1964, a pilot plant was installed near the Lisbon field, Moab, Utah, to test some of our solvents as well as a competitive solvent on a sour-gas stream; results of the pilot plant tests on methyl cyanoacetate (MCA) and propylene carbonate (PC) are reported here. The pilot plant is still in use to treat fuel gas for gas compressors. Description of Field Pilot Plant The Steams-Roger Corp. of Denver was selected to design and install the field pilot plant, which is shown in Fig. I in a simplified flow diagram. The pilot plant processed up to 1.8 MMcf/D at a pressure of 770 processed up to 1.8 MMcf/D at a pressure of 770 psig during the runs described here. Raw gas psig during the runs described here. Raw gas contained about 30 percent CO and 1 percent H S. Treated gas was obtained with as little as a few tenths of a percent of CO and less than 1/4 grain of H S per 100 scf of gas. The major equipment included in the pilot plant is described below. JPT P. 483