Sensitive colorimetric sensors for visual detection of carbon dioxide and sulfur dioxide

A series of highly efficient, solid-state sensors for direct colorimetric detection of gaseous CO sub(2) and SO sub(2) is described. The basic components of the sensors are a CO sub(2) and SO sub(2)-responsive, tertiary amino alcohol, such as triethanolamine, and a pH-indicator dye, e.g. cresol red, immobilized on a porous gamma -aluminum oxide support. These sensors show distinct visual responses to low levels of CO sub(2) and SO sub(2) present in air. A structure-performance relationship was also established for these sensors. To increase the shelf-life, tertiary amino alcohols were covalently attached to the porous alumina support. These porous alumina-supported tertiary amino alcohols also offer potential for use as adsorbents for acidic gases such as CO sub(2) and SO sub(2) with the ability to selectively release these under different conditions, allowing easy separation from a gas stream.