Thermal effects, mixing-cell

Adsorption Work. In the adsorption work, glass beads were used as a blank to determine whether the heat of dilution of the surfactant or changes of flow pattern lead to a thermal effect. At both 25° and 30° C, the heat effect of flowing an increasing concentration from 0.1 to 2% in five steps was not detectable. Since the amount of adsorption to solid glass beads is small, it can be concluded that there is either very little mixing of the two solutions as the interface between them moves through the cell, or if there... 

The quantity experimentally determined is the thermal effect accompanying the mixing in the calorimetric cell of a solubilizate-organic solvent solution with a water-surfactant-organic solvent microemulsion at a given surfactant concentration ([S]). This thermal effect, corrected for the enthalpy of dilution of both solutions and referred to 1 mole of the solubilizate, corresponds to the enthalpy of transfer (AH,) of the solubilizate from the organic to the micellar phase. In order to analyze the calorimetric data (AH, [S]), it is also necessary to develop... 

The sample to be analyzed, say C60 fullerene, is mixed with an appropriate amount of KBr in an agate mortar and then transferred into a press and compressed at 4,000 Kg into a pellet with a diameter of 1.2 cm and a thickness of 0.2 cm. The pellet was mounted into the sample holder of the Specac variable temperature cell and inserted into the cell. The cell was then evacuated with the aid of a pump to a vacuum of 0.1 torr and then heated gradually at 120°C in order to permit the humidity absorbed on the internal surfaces of the cell and in the KBr pellet to evaporate. The sample was then cooled to the desired temperature to record the infrared spectrum. In order to go below room temperature, use was made of liquid nitrogen, added cautiously and in small amount in the cavity present inside the cell. Such cavity is connected with the sample holder and permits to cool the sample to the desired temperature. The temperature of the sample was monitored with adequate thermocouples. The lowest temperature reached with this apparatus was -180°C (93K) while the highest temperature was +250°C. Heating is provided by the Joule effect and an external thermal control unit. 

The extent of gas dispersion can usually be computed from experimentally measured gas residence time distribution. The dual probe detection method followed by least square regression of data in the time domain is effective in eliminating error introduced from the usual pulse technique which could not produce an ideal Delta function input (Wu, 1988). By this method, tracer is injected at a point in the fast bed, and tracer concentration is monitored downstream of the injection point by two sampling probes spaced a given distance apart, which are connected to two individual thermal conductivity cells. The response signal produced by the first probe is taken as the input to the second probe. The difference between the concentration-versus-time curves is used to describe gas mixing. 

The efficient use of current supplied during the oxidation of bio-refractory organic pollutants by electrochemical treatment imposes to adopt an electrocatalytic material such as boron-doped diamond (BDD) that produces hydroxyl radicals. At the end of electrochemical treatment, a low transfer of pollutants occurs toward the hydroxyl radicals due to the reduced concentration of pollutants in the bulk, and this condition reduces the degree of utilization of BDD anodes. Ex-cell-mediated oxidation (via persulfate) of organic pollutants can be applied after electrochemical treatment, and its effects are a higher utilization of BDD anodes and an efficient removal of pollutants at the end of treatment, when their concentrations achieve low values. This oxidation consists of various steps after the electrochemical production of a precursor of active oxidants, it is initially mixed with the wastewater and successively activated by thermal or ultraviolet energy in order to generate active oxidants that efficiently oxidize the pollutants. 

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