水力空化与臭氧联合降解罗丹明B

针对超声空化处理量小、水力空化处理效果不够理想及臭氧虽然有较好的水处理效果,但臭氧容易从液体中冒出,造成臭氧的浪费的问题,探讨了增强水力空化的方法并采用水力空化与臭氧联合以提高臭氧利用率.首先研究不同通气量的臭氧单独作用时,对罗丹明B的降解率；其次研究臭氧与水力空化先后参与对罗丹明B降解时的降解率；最后将臭氧与水力空化进行联合,详细分析了1 mm孔径与2 mm孔径的两个穿孔板在固定条件下产生的水力空化与臭氧联合的降解效果,并改变孔径、孔数、进口压强等参数进行实验,研究不同条件下的降解效果.结果显示,臭氧对罗丹明B具有很强的降解作用,水力空化与臭氧先后降解对降解率提高不大,不同的穿孔板在不同的条件下产生的水力空化都可以大大提高臭氧的降解效果,水力空化使臭氧能够基本全部利用,避免了臭氧的浪费,同时臭氧分解成的微小气泡也增强了水力空化效应.     

超声化学原位合成Al2O3（p）/Al纳米复合材料的组织及其机理（英文）

采用超声化学原位反应,以Al-K2ZrF6-Na2B4O7为反应体系,制备Al2O3(p)/Al纳米复合材料。利用扫描电镜和透射电镜,研究高能超声对复合材料组织和颗粒收得率的影响及加入K2ZrF6对反应过程以及增强颗粒与铝基体的界面的影响。X射线衍射(XRD)、扫描电镜(SEM)与透射电镜(TEM)结果表明:所制备的复合材料增强颗粒为Al2O3,Al2O3颗粒在基体中分布均匀,其形貌为近球形,尺寸20~100nm,界面干净且无界面产物。利用经过二次开发的Image-J软件对Al2O3颗粒收得率进行分析,结果表明,Al2O3颗粒收得率随着超声功率的增大呈现出先增大后减小的变化规律。当超声功率达到0.4kW时,颗粒分布最好且数量最多。并对其反应机理也进行了探讨。     

功率超声波在食品工艺中的应用

超声波具有多种物理和声化学效应 ,在各行各业中应用广泛。该文主要介绍功率超声波在食品加工方面的应用。除了能从正反两方面影响活细胞的生长和酶的活性外 ,作为一种辅助加工手段 ,功率超声波还能用于提取、结晶、解冻、乳化、过滤 ,干燥以及精加工过程     

Relationship between sound pressure and reaction rate in sonochemical reaction

Relationship between sound pressure in a sonochemical reactor and degradation rate of organic compounds, p‐chlorophenol and p‐nitrophenol, was investigated. Reaction rates were analyzed as first‐order reaction. As a result, linear relationship was shown for each compound. Slope indicating the first reaction rate constant was remarkably affected by the position of the reaction flask. The sound pressure profile was measured and the relationship between the averaged pressure in a flask and the rate constant was shown. The relation was found to be remarkably different between the two. The threshold values were observed as 67kPa for p‐chlorophenol and 22kPa for p‐nitrophenol, respectively. From these results, it was shown that nature of compounds affects the dependency on sound pressure.     

Enhanced Antibacterial Activity of Nanocrystalline ZnO Due to Increased ROS‐Mediated Cell Injury

An innovative study aimed at understanding the influence of the particle size of ZnO (from the microscale down to the nanoscale) on its antibacterial effect is reported herein. The antibacterial activity of ZnO has been found to be due to a reaction of the ZnO surface with water. Electron‐spin resonance measurements reveal that aqueous suspensions of small nanoparticles of ZnO produce increased levels of reactive oxygen species, namely hydroxyl radicals. Interestingly, a remarkable enhancement of the oxidative stress, beyond the level yielded by the ZnO itself, is detected following the antibacterial treatment. Likewise, an exposure of bacteria to the small ZnO nanoparticles results in an increased cellular internalization of the nanoparticles and bacterial cell damage. An examination of the antibacterial effect is performed on two bacterial species: Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive). The nanocrystalline particles of ZnO are synthesized using ultrasonic irradiation, and the particle sizes are controlled using different solvents during the sonication process. Taken as a whole, it is apparent that the unique properties (i.e., small size and corresponding large specific surface area) of small nanometer‐scale ZnO particles impose several effects that govern its antibacterial action. These effects are size dependent and do not exist in the range of microscale particles.     

Hydrodynamics and mass transfer of oscillating gas‐liquid flow in ultrasonic microreactors

Ultrasonic microreactors were used to intensify gas‐liquid mass‐transfer process and study the intensification mechanism. Fierce surface wave oscillation with different modes was excited on the bubble. It was found that for slug bubbles confined in smaller microchannel, surface wave oscillations require more ultrasound energy to excite due to the confinement effect. Cavitation microstreaming with two toroidal vortices was observed near the oscillating bubble by a streak photography experiment. Surface wave oscillation at the gas‐liquid interface increases the specific surface area, while cavitation microstreaming accelerates the interface renewal and thus improves the individual mass‐transfer coefficient. With these two reasons, the overall mass‐transfer coefficient was enhanced by 3–20 times under ultrasonication. As for gas‐liquid flow hydrodynamics, ultrasound oscillation disturbs the bubble formation process and changes the initial bubble length and pressure drop. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1294–1307, 2016     

硬磁／软磁纳米复合颗粒的声化学制备

利用超声波使金属有机化合物Fe（CO）5在低温和惰性气氛环境中分解生成纳米尺寸Fe颗粒，并使其包覆在硬磁颗粒表面，制备出Sm-Fe-N，Fe和Nd-Fe-B／Fe纳米复合粉末。透射电子显微镜及能谱分析表明，Fe（CO）5声化学分解得到了纯净的Fe颗粒，其尺寸约为5nm；运用场发射扫描电子显微镜对包覆产物的显微形貌进行了观察，结果显示Fe在两种永磁颗粒表面可以实现均匀包覆，且包覆的Fe含量可调；能谱分析表明，超声化学包覆过程中未生成其他副产物。此外，讨论了纳米Fe颗粒的包覆制备工艺条件和机制。     

超声技术在工业废水处理中的现状与进展

讨论了单频超声降解有机废水和多频（二维正交和三维正交）超声降解有机废水，后者具有明显的增强效应。并根据研究现状和实验研究，提出研究方向：（1）深化声化学的反应机理研究，并研究超声与其它氧化技术的联合作用，寻求工业实践中有效、可行、能提高处理效率的途径；（2）探索不同频率的声化学效应，特别是多种频率超声的协同作用机理；（3）从技术和经济的角度，着力探究超声技术和设备在处理工业有机废水中的实施方法，为超声在工业中的广泛应用提供依据。     

超声技术在无机材料合成与制备中的应用

介绍了超声作用的基本原理，综述了超声技术在悬浮液处理、SiO2声凝胶制备和无机复合粉体均匀分散中的应用。以及声化学在无机材料合成中的应用。利用超声技术和声化学制备粉末，有希望制备出均匀的纳米粉末，有利于改善加工特性和材料的最终性能，以及制备出新的材料。