Regenerative Trace Contaminant Control: New Test Method for Effects on Solid Amine

Tests using the Thermogravimetric Analysis (TGA) techniques showed this approach to be a relatively simple and rapid method for assessing the affinity of trace contaminants for a solid amine, CO₂ sorbent. Regenerative CO₂ sorbents are applicable to many space systems air revitalization applications for removal of CO₂. Sorbents may be chemically non-specific as regards reversible adsorption-desorption, chemicals other than CO₂ can be regeneratively removed from spacecraft air. These other chemicals, present in trace amounts, may also interfere with the primary CO₂ removal function. TGA test procedures were developed to determine adsorption-desorption behavior of trace contaminants on a regenerative solid amine sorbent: Hamilton Standard, material - C (HS-C). Seven trace contaminants were tested; the TGA test procedures:

• Evaluated the TGA method for studying sorbent materials in air revitalization systems
• Determined the adsorption/desorption characteristics of the HS-C to CO₂
• Detailed the adsorption/desorption effects of trace contaminants on CO₂ removal
  The tests showed trace contaminants to be in one of three classes:
• Regeneratively adsorbed and desorbed
• Inert, no effect
• Poison - interferes with CO₂ removal.

Trace contaminants which poison the sorbent can then be identified and design provisions in air revitalization systems made. Acetone, in dry air at 1% concentrations, bonds irreversibly to the HS-C material. With the exception of acetone, the other six trace contaminants effected a slight reduction in the CO₂ adsorption/desorption function. Methanol, Freon 21, and Freon 13B1 were adsorbed and fully desorbed, indicating the possibility of regenerative removal of these contaminants.