Nitrogen sparging

Transfer the dried beads into a three-neck flask with a thermometer, a nitrogen inlet, and a ventilation stopcock. Add the solution of the silanation agent to the flask with nitrogen sparge. 

Anaerobic phase The dissolved oxygen quickly vanishes due to nitrogen sparging. Eventually, dye concentration decreases following a pattern that closely reproduces those observed in experiments. It is worth noting that the thickness of... 

Figure 13.10. Calibration curves for optical sensor and Clark-type oxygen electrode. The phase response of optical sensor and the voltage response of the Clark-type electrode is plotted against percent oxygen in the gas mixture (oxygen and nitrogen) sparged. While the Clark-type electrode shows a linear calibration the optical sensor shows a Siem-Volmer lype relationship (see Section 13.10.2).

Fig. 3.19 Cathodic polarization curves for 100 and 10,000 ppm Fe3+ (as FeCI3) on platinum in nitrogen-deaerated solution. The increase in current density at 400 mV (SHE) is due to a velocity effect in introducing nitrogen sparging into the solution. The limiting current density is increased by a factor of about 100 on increasing the concentration from 100 to 10,000 ppm. The increase in current density near-100 mV (SHE) is due to hydrogen ion reduction resulting from a decrease in pH dueto Fe3+ hydrolysis.

Characterization of Volatile Fraction. Volatile organic compounds found in oily wastewaters consist primarily of lower-molecular-weight aliphatic and aromatic hydrocarbons. Because of its relatively high vapor pressure, this fraction is quite often lost during analysis of oily wastes. For this reason a separate procedural step was incorporated into the overall scheme for analysis of the volatile fraction. An unfiltered sample of oily waste is used in this determination. The volatile fraction is separated from water by means of nitrogen sparging and collected in an activated carbon absorption column. The collected compounds are desorbed into carbon disulfide and analyzed by GC. 

Copolymer Reactions. Rearrangement Reactions. Two poly(DHA-co-4VP) materials with 10-15 mole % DHA were thermolyzed in refluxing DMF (see Reaction 1). A strong nitrogen sparge was used to help remove the tertiary amine. The isolated poly(4-vinylpyridine-co-isopropenyl isocyanate) materials were insoluble in ether but soluble in chloroform, they had a strong band in the IR spectra at 2260 cm"1 and a weak band at 1710 cm"1, and they consisted of 1.5-2.0 wt % NCO. A sample of the thermolysis solution had a shelf life, i.e. lack of gelation, of about five days. 

Before each experiment, the cell and the electrodes were rinsed with diluted sulphuric acid, alcohol and finally de-ionized water. The dissolved oxygen was removed with nitrogen sparging for one hour, after which a nitrogen blanket was sustained above the solution. All apparatus warmed up for several hours and the voltage source (1) supplied approximately the expected current to a resistance. 

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