The Conductivity of Aqueous K₂CO₃ at Elevated Temperatures and Pressures, Measured using the AC van der Pauw Technique

Abstract

Conductivity measurements of aqueous K2CO3 were performed using the van der Pauw method and a specially designed sample holder with Pt wires as electrodes. The resistance was measured using alternating current. The conductivity of 10-50 wt% aqueous K2CO3 was measured at room temperature and ambient pressure. The conductivity was found to increase with concentration up to 30-40 wt%, and decline at higher concentrations. Furthermore, the conductivity of 5-30 wt% aqueous K2CO3 was measured up to 180-200 °C at 30 bar. The highest conductivity measured was 1.34 S/cm at 172 °C for 30 wt% K2CO3 (aq). The conductivity was found to increase with concentration and also temperature for 5-15 wt%. For 20 and 30 wt% K2CO3 (aq) the conductivity also increased with temperature up to a certain point and then a drop was seen at 150 and 180 °C, respectively. The activation energy was also obtained by fitting the data to a modified Arrhenius equation. The activation energy was found to be in the range 0.14-0.17 eV and did not appear to be concentration dependent.

High temperature and pressure electrochemical test station

“…The electrochemical cell holder for measuring the conductivity of a liquid electrolyte using the van der Pauw technique 11,12 is shown in Figure 5(a). Pt black coated Pt wires are placed on the sides of a PTFE beaker and kept in place by a PTFE pellet at the bottom and a PTFE wire at the outer top of the electrochemical cell holder.…”