300 kHz 조건에서의 초음파화학적 산화반응에 대한 연속식 가스 주입 효과

Abstract

The effect of gas sparging on sonochemical oxidation was investigated in a 300 kHz sonoreactor under various liquid height/volume conditions (5∼30λ, 3.4∼9.0 L), determined by the wavelength of the applied frequency. The electrical input power was maintained constant for all cases<repetition of input>. Sonochemical activity drastically decreased from 15λ and the liquid height of 10λ was suggested as the optimal height for 300 kHz without gas sparging. In our previous research, the sonochemical activity observed was five-times higher when air sparging was applied for 36 kHz. On the other hand, no enhancement was obtained at 10, 15, 25 and 30λ using air sparging (1, 3, and 6 L/min) for 300 kHz in this study <consider using a conjunction such as and when joining words or numbers in a sequence). Small enhancement by air sparging was observed only at 20λ and optimization of gas sparging was conducted at 20λ using various gases including air, Ar, O2, N2, and mixtures of Ar and O2. It was found that gas sparging using pure Ar or pure O2 resulted in lower sonochemical activity compared to that of air sparging due to the imbalance between the intensity of cavitation phenomena and the generation of oxidizing radical species. Consequently, the gas mixture of Ar: O2=80%:20% (DO saturation ≈ 100%) was suggested as an optimal gas sparging condition.