Solid state systems for the potentiometric determination of CO 2

Abstract

In a survey of solid state systems for the potentiometric determination of CO(2) their different fundamentals, possibilities and problems are demonstrated. Experimental results are given, obtained from sensors in which Na(2)CO(3) reacts electrochemically with an oxide forming the sodium salt thermodynamically stable in contact with it. Sensors with Na(2)YZr(PO(4)) as solid electrolyte and MoO(3) or SiO(2) did not yield long-term stable signals, probably mainly because of chemical reactions between the oxides and the solid electrolyte. Satisfactory results were obtained with galvanic cells represented by the symbol. Their standard cell tensions U* (= -emf*) determined with different test gases are in relatively good agreement with values thermodynamically calculated.

The measurement of dissolved and gaseous carbon dioxide concentration

“…After several weeks of operation this time increases tenfold (150 ms) [61]. Solid electrolyte CO 2 sensors using the Ni/carbonate composite as a measuring electrode are suited for measurement of CO 2 in equilibrated water gases [62]. Some authors reported that Nasicon-based CO 2 sensors using mixtures of semi-conducting oxides and carbonates such as SnO 2 or ITO (indium tin oxide) [63] and In 2 O 3 [64] as electrodes are able to measure at room temperature.…”