【摘要】 利用空化释放出的能量对过程进行强化是能量利用的新途径,羟自由基·OH产量直接反应了空化的强度和效果,为了提高·OH产量,寻求最优空化条件,对水力空化·OH产量的影响因素进行了实验研究。以多孔孔板作为空化的发生元件,采用亚甲基蓝作为·OH的捕捉剂,利用紫外-分光光度法间接测量·OH产量。分析了亚甲基蓝溶液浓度、入口压力、溶液温度、氧气混合速度和反应时间对·OH产量的影响规律。研究表明,亚甲基蓝溶液浓度在16～19μmol/L时对·OH的捕捉有较高的灵敏度和精确度;入口压力、溶液温度和氧气混合速度分别为0.2MPa、30℃和45L/h的条件时,OH产量最高;反应时间与·OH产量呈近似线性关系。更多还原

【Abstract】 The cavitation associated with the formation,growth and the collapse of micro-bubbles leads to the generation of very high pressures and temperatures locally,which can cause a series of physical and chemical reactions. The molecular link of hydrone in the solution is broken by the energy released from the high pressures and temperatures in hydrodynamic cavitation,which would generate the hydroxyl (·OH) radical. Therefore,the energy released in hydrodynamic cavitation can be used to enhance some chemical reaction,as a new approach of energy utilization. In addition,the production of hydroxyl radical reflects the strength and effect of cavitation. The influencing factors of ·OH production of hydrodynamic cavitation are investigated in this paper in order to increase the production of ·OH and find the best cavitation reaction conditions. Multi-hole orifices are used as the reactor of hydrodynamic cavitation. Methylene Blue (MB) is used as the catcher for hydroxyl radicals induced in hydrodynamic cavitation. An ultraviolet-visible spectrophotometer is used to measure the amount of induced hydroxyl radicals. The relations between ·OH production and MB solution strength,inlet pressure,solution temperature,mixing velocity of oxygen are analyzed. The experimental results show that the experimental method mentioned above is an efficient approach to quantitatively analyze the relationship between the production of ·OH and the cavitation intensity or the cavitation effect. The catching ratio to the ·OH is basically constant under the condition that the MB solution strength is in the range of 16 to 19μmol/L for the ideal sensibility and accuracy of catching ·OH. The production of ·OH is the highest under the condition that the inlet pressure is equal to 0.2MPa,the solution temperature is equal to 30℃ and the mixing velocity of oxygen is equal to 45L/h. In addition,under adequate structural parameters,the production ·OH is approximately linearly related with the reaction time of cavitation. The production of ·OH can be raised through adjusting the inlet pressure,solution temperature,mixing velocity of oxygen,reaction time and other macro-parameters,as in the optimal cavitation conditions.更多还原