Deionized-alkaline system

Figure I. Deionized-alkaline system by chemical feeder process Dl is deionized water alkaline earth is a divalent compound, i.e., Ca+2 or Mg+2.

The Deionized Water-Alkaline System. The DI—Ca water analyses from the chemical feeder process are shown in Table I. As the amount of calcium ions in the deionized water was increased, the conductivity values became higher. The amounts of calcium in the Dl-Ca water can be measured by conductivity. The pH of the deionized water was 6.3. The pH of saturated calcium hydroxide solution is 12.3. Addition of 9.2 ppm Ca as Ca(OH)2 in the deionized water raised the pH to 9.9. The level of the pH increased with additional amounts of calcium ions in the DI water. The measurement and adjustment of the calcium solution flow was essential, both for washing and for the deacidification efficiency. 

The typical cleaning sequence of a reusable cuvet and/or reaction vessel Involves aspiration of the reaction mixture out of the cuvet at an in situ wash station. A detergent, alkaline, or acid wash solution is then repeatedly dispensed into and aspirated out of the cuvet. The cuvet is rinsed several times with deionized water and dried by vacuum or pressurized air. Optical clarity is verified automatically in most systems (usually while the cuvets contain the water). If performance is unsatisfactory, the operator is alerted to replace individual cuvets. If the cuvets are not replaced promptly, the system cannot be used for analysis until they are replaced, the results for the unsatisfactory cuvets will be flagged. 

For water deionization, a combination of an ion exchanger Alter with a packing of a weak alkaline anion exchanger following the Alter, with a cation exchanger in its H form in the system and equipped with a ventilation tower for COo removal is recommended. 

In a three-necked flask equipped with a mechanical stirrer, the tetraamine and solvent PPA were added. The solution was stirred at 110°C under nitrogen atmosphere for about 1.5 h to get a homogeneous solution. An equimolar amount of diacid was added to the solution, and the reaction was continued for 12h at 140 °C. Then a catalytic amount of phosphorus pentoxide and triphenyl phosphite (TPP) were added into the system. The solution became brownish and viscous. It was heated to about 230 °C for another 24 h and then poured into the water, washed with deionized water several times, and neutralized by alkaline solution. Finally, the polymer was dried under vacuum for 24h [15,16]. 

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