Application And Research Of The Dissolved Gases And Hydrophobic Interface Of Nanobubbles

The statement that nanobubbles possibly exist at solid/water interface was originated from the study of the mechanism of long-range attractive force between hydrophobic surface.The measurements of surface force apparatus indicated that the presence of nanobubbles maybe related to the hydrophobic force.Then the results from colloid probe AFM provided more sophisticate features of the hydrophobic force and supported that the force may be caused by the nanobubbles at the interface.Meanwhile,there was a flurry of reports that the hydrophobic force is closely related to the amount and the kind of dissolved gas. Additionaly, the existence of nanobubbles was supported by the IR spectroscopy and the relvant studies on the interaction between colloids. But all of the above evidence could just prove the presence of nanaobubbles in an indirect way. The evidence searching made a breakthrough in 2000 and 2001 when AFM images of nanobubbles were published.After that, the presence of nanobubble was proven further by the measurements of neutron reflectivity.The accumulation of gas at the water/solid interface on the nanometers cale has great implications on many fields, for example, the adhesion on the surface, the stability of colloidal system, and the behaviors of biomolecules or cells at the interface.And the aggregation of gas at the solid-water interface has been reported to lead to the fluid slippage. Such effects may reduce the resist force on the fluid, which will inevitably have a great impact on the hydrodynamics on micoscopic scale. However, presently there are few people to do research about of nanobubbles. Therefore we do some preliminary research of nanobubbles applications at bioscience and applied surface science. It has been systematically studied and some interesting results were obtained as follows.(1) In this thesis, the effect of dissolved gas and nanobubbles on mosquito-fish which at the extreme hypoxic environment are studied. The impact of degassing to nano- bubbles which at solid-liquid interface is observed by AFM. The results showed that 1) The existence of nanobubbles at solid-liquid interface; 2) Degassing process can make nanobubbles disappeared at solid-liquid interface; 3) Particulate dispersion system can provide adequate nano-gasbubbles which mosquito-fish can be used highly efficiently. It is inferred that the nanobubbles in water and at the surface of particles can provide enough oxygen for mosquito-fish to survival. The ability of different materials particles formed nanobubbles on the surface are also different.(2) For obtaining well dispersed sol with over saturated concentration of hydrophobic particles, the particles and water solvent were treated using deeply degassing process. The characterization of the sol was performed by Tyndall effect and conductivity measurement. In the sol, Tyndall scattering results showed that deeply degassed samples (DDS) had more uniform distributions than those non-treated. In comparison with same samples, the conductivity measurements for DDS also presented much higher values up to 30 to 80 percent. Turbidity tests show that the deeply degassing method can improve the stability of colloidal dispersion. The turbidity value can be increased to 2-3 times than the original.