报告题目： Water and Wastewater Treatment by Acoustic Cavitation using High Frequency Transducers（详见附件）
报 告 人： Michael R. Hoffmann 教授，加州理工研究生学院院长
（James Irvine Professor & Dean of Graduate Studies，California Institute of Technology）
报告时间： 2006-07-24 下午
报告地点： 环境系馆

Water and Wastewater Treatment by Acoustic Cavitation using High Frequency Transducers

by

Dr. Michael R. Hoffmann

James Irvine Professor of Environmental Science

Dean of Graduate Studies

Engineering & Applied Science

California Institute of Technology

Pasadena, CA 91125

Abstract

The chemical and physical effects of electrohydraulic cavitation induced by ultrasonic irradiation over the frequency range of 15 to 1000 kHz will be discussed.  Ultrasonic irradiation appears to be an effective method for the rapid destruction of organic and selected inorganic chemical contaminants present in water.  The degradation of chemical compounds by acoustic cavitation is shown to involve three distinct chemical pathways: 1) oxidation by hydroxyl radical formed during the vapor phase decomposition of water, 2) pyrolytic decomposition in transient collapsing cavitation bubbles due to high localized temperatures (e.g., 5000 K) and pressures (e.g., 1000 atm), and 3) due to supercritical water (T ³ 647 K and P ³ 220 atm) reactions. 

Detailed reaction mechanisms and mathematical models for the degradation of halogenated hydrocarbons, surfactants, and perfluoro compounds such as perfluorooctane sulfonate, perfluorooctanoic acid, and perfluor-alcohols will be presented.  The reaction rate dependencies on frequency, applied power, temperature, dissolved gases, substrate solubility, and multiple wave harmonics will be discussed.  Potential environmental applications, reactor design considerations, optimization, limitations, and scale-up of this physicochemical water treatment technology will be addressed.