Colorimetric polymer film sensors for dissolved carbon dioxide

✍ Scribed by Andrew Mills; Qing Chang

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 648 KB
• Volume: 21
• Category: Article
• ISSN: 0925-4005
• DOI: 10.1016/0925-4005(94)80008-1

✦ Synopsis

Plasticized and unplasticized polymer calorimetric film sensors for gaseous COz, containing the dye m-cresol purple, are tested as sensors for dissolved CO,. The plasticized polymer m-cresol purple 6lm sensor develops a measurable degree of opacity when exposed to aqueous solution, especially in neutral, compared with alkaline, solution. However, it is shown that a presoaked, fogged plasticized polymer m-cresol purple film does function as a quantitative sensor for dissolved COz over the range a%

COz. An unplasticixed polymer m-cresol purple film remains largely clear upon exposure to aqueous solution and also functions as a quantitative sensor for dissolved CO2 over the range @4% CQ. However, in both types of films the dye interacts with electrolytes present in solution; invariably the dye appears to be converted from its initial deprotonated form (blue) to its protonated form (yellow) and the rate of this process appears to increase with increasing ionic strength, anionic charge and decreasing pH. The 90% response gnd recovery times for an unplasticized tilm are determined as 19 s (COz:O+5%) and 21 s (CO,:5 +3.6%), respectively.