Thermal properties of aminopolycarboxylic acid solutions in the temperature range 20–80°C

Abstract

The thermal properties (thermal conductivity, thermal diffusivity, and volumetric heat capacity) of aminopolycarboxylic acids, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diet hylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), 1,2-diaminocyclohexanetetraacetic acid (DCTA), and ethyleneglycol-bis-(2-aminoethylether) tetraacetic acid (EGTA), in dilute solutions of sodium hydroxide were measured in the temperature range 20–80°C. The measurements were performed with a hot-wire (strip) technique. The results show that the values of the thermal properties depend on the number of nitrogen atoms and the number of carboxyalkyl groups, which are bounded to the nitrogen atom, of the aminopolycarboxylic acid and also on the concentration of the investigated compounds in the medium and the temperatures. The mechanism of heat transfer is discussed and the role of convection is taken into consideration.