温差法制备纳米气泡及温度的影响

Investigation on the temperature difference method for producing nanobubbles and their physical properties

通过一系列的实验建立了利用冷水(4±0.1℃)和热水(25～40℃)进行替换即温差法制备界面纳米气泡的方法.原子力显微镜(AFM)观察显示:温差法也能在疏水的高序热解石墨(HOPG)表面上产生稳定的纳米气泡.统计结果显示:热水温度在25～38℃范围内,产生纳米气泡的数量随着热水温度的升高而增多,当热水温度为38℃左右时达到最大值,之后随着热水温度的升高反而减少;每平方微米纳米气泡气体的总体积在37℃时达到最大值;温差法也能产生纳米气层和双层结构,其性质与前人发现的一致.

For producing interfacial nanobubbles, a systematic experiment, called temperature difference method, was carried out by replacing low temperature water （LTW） with high temperature water （HTW） at the highly oriented pyrolytic graphite （HOPG） - water interface. When LTW （4 ± 0.1 ℃ ） mixed with HTW （25 -40℃ ）, nanobubbles were observed by atomic force microscope（AFM）and their size, number and total volume per square micrometer were measured. The result showed that when the temperature of HTW was lower than 38℃, the number of nanobubbles increased with the increase of temperature and reaches its maximum at 38℃. When the temperature of HTW was above 38℃, the number of nanobubbles decreased with the in- creasd of temperature. The maximum average total volume was obtained at 37℃, and then the volume decreased with further increasing temperature due to the gas outflow during the replacement process. The coexistence of nanobubbles and pancake-like gas layers were also found by using temperature difference method. The characteristics and reasons for the formation were consistent with earlier research.