A Piezoelectric crystal detector for continuous monitoring of water evolved during thermal decomposition reactions.
A method for the continuous monitoring of water vapour evolved during thermal decomposition reactions is developed based on the reversible adsorption of water on a bare piezoelectric crystal with nickel electrodes. Gaseous decomposition products formed in the furnace chamber of the thermoanalytical equipment are collected and transported to the detector cell by the carrier gas. A linear relationship exists between the decrease in vibrational frequency of the crystal and the concentration of water in the carrier gas up to 900 mug/l. H(2)O [1200 ppm (v/v)]. The signal curve of the piezoelectric water monitor can be recorded simultaneously along with the TG, DTG and DTA curves and used to identify the decomposition step(s) in which water was formed. CO, CO(2) and low molecular weight hydrocarbons do not interfere. Condensable organic crack products can be removed by a suitable pretrap.
Kristóf
J
J
Department of Analytical Chemistry, University of Veszprém, H-8201 Veszprém, P.O. Box 158, Hungary.