Abstract
A technique is proposed to improve the collection efficiency of a small amount of volatile organic compounds, especially explosive materials, in the gas by impinger, which is generally used as gas collection device for analysis. Eugenol was used as a simulated substance of explosives. The sample gas containing specific amount of eugenol was collected in pure water by the impinger. The concentration of eugenol in water was measured by gas chromatography. The experimental results show that the collection efficiency of eugenol by the impinger increased as the water level (volume) increased. The bubble motion in the impinger observed by high-speed photography indicates that the averaged values of equivalent diameter and rising velocity of bubbles were reduced as the water level increased. This reduction yields the increase of the resident time of bubble per unit volume of water, which enhances the dissolution of eugenol. On the basis of these characteristics, small glass beads were stuffed into the impimger to increase the resident time per unit volume. The collection efficiency per unit volume of water was greatly improved by stuffing the glass beads. Finally, the cleaning-in-place process of the impinger was also achieved by intermittent gas supply under the continuous water supply.
