Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/26938
- Water-in-oil emulsion foaming by thiourea nitrosation: reaction and mass transfer
da Silva, Gabriel;
Dlugogorski, Bogdan Z.;
Kennedy, Eric M.
- A study has been undertaken into the chemical production of gas bubbles within a concentrated water-in-oil emulsion, typical of those used as emulsion explosives. Chemical foaming was initiated by the introduction of a concentrated sodium nitrite solution to the emulsion, and the measurement of the decreasing emulsion density with time served to estimate the rate of nitrogen production. A conversion of emulsion density to nitrite ion concentration facilitated a kinetic analysis of the data. The change in nitrite ion concentration follows a rate equation which indicates that the rate-limiting reaction step corresponds to the N-nitrosation of thiourea by ON⁺, with an apparent rate constant of 0.22 M⁻¹ s⁻¹ at 25 °C. Tests over a temperature range of 25 to 50 °C yielded an activation energy of 59 kJ mol⁻¹. A mass-transfer model describing the rate of diffusion between aqueous droplets is presented. This model suggests that chemical kinetics, rather than molecular diffusion, is the rate-limiting phenomenon in the foaming of emulsions. Supporting this finding, the kinetic experiments in emulsion returned very similar results to previous experiments performed in aqueous media under similar conditions.
- AIChE Journal Vol. 52, Issue 4, p. 1558-1565
- Publisher Link
- American Institute of Chemical Engineers - Wiley Interscience
nitrite ion concentration;
chemical production of gas bubbles
- Resource Type
- journal article