초음파에 의한 염소계 화합물의 분해특성 연구

Abstract

Currently the environmental remediation research with ultrasound has been actively accomplished. The processes using ultrasound treat various contaminants and they are also used in the advanced oxidation processes. The reaction mechanisms in ultrasound consist of direct pyrolysis and radical reaction in cavitation bubbles. The purpose of this research is to investigate the effect of temperature, power intensity, and saturated gas on degradation mechanisms in ultrasound applied processes. The effects of the physico-chemical properties of the target materials are also studied. The experiments are conducted with TCE solutions at different temperatures, power intensities, and saturated gases. The TCE degradations are assumed to be 1st order reactions. The degradation rates were increased under lower temperature conditions. This may be due to the ‘cushion effect’ The degradation rate was increased with higher power intensities. It has been shown that the maximum temperatures in cavitation bubbles were affected by saturated gas components. The reactions were fastest with the solutions in which argon gas has been saturated. The reaction rate was fast in the order of solutions with argon, air, and nitrogen. The pH decreased from pH 7 to pH 3 for 120-minute reaction. The production of H+ caused the pH to drop. In the case of CT the degradation rate was faster with high vapor pressure than with TCE and 1, 2, 3 - TCP. The order is CT > TCE > 1, 2, 3 TCP. While volatile compounds such as TCE and CT are mainly degraded inside of cavity bubbles, non-volatile compounds such as 1, 2, 3 - TCP hardly react at low frequency (20 kHz).