相互作用力及液膜排液动力学研究进展

颗粒气泡间相互作用力及液膜薄化破裂动力学是揭示浮选黏附机理的核心,也是近年来浮选胶体化学领域的研究热点。为深入明晰浮选黏附机理,对当前颗粒气泡间相互作用力及液膜排液动力学模型理论研究进展进行了系统综述。对于颗粒气泡间相互作用力,疏水引力可克服颗粒气泡间范德华力和静电斥力,诱发黏附。不同作用程范围内疏水力的来源机制不同:长程疏水力(20 nm)主要源于固液界面亚微米/纳米气泡桥接,而短程疏水力(20 nm)则主要源于固液界面水分子重排效应。由于疏水力强烈的吸引性和气液界面变形,颗粒气泡间疏水力的定量表征仍存在较大的挑战。对于颗粒气泡间液膜排液动力学模型,最具代表性的有Stefan-Reynolds平坦膜模型,Taylor模型和Stokes-Reynolds-Young-Laplace(SRYL)模型。Stefan-Reynolds及Taylor模型并未考虑排液过程中气泡表面曲率的变化,其应用存在着较大的局限性。SRYL模型则在描述液膜薄化速率的同时,兼顾了气泡表面在流体力和表面力等外力作用下的变形行为。在给定起始与边界条件下,SRYL模型通过数值迭代法与液膜排液试验测试结果对比,可以计算出颗粒气泡间的相互作用力信息;也可通过与相互作用力试验结果对比获得液膜排液数据。在今后的研究中,应重点将SRYL模型与试验测试相结合,对颗粒气泡间疏水力进行定量表征,揭示浮选黏附机理。

Advance in the interaction force between bubble and particle and the thinning dynamics of thin liquid film

Interaction force and the thinning rupture dynamics between bubble and particle is the key to reveal the attachment mechanism of coal flotation.It is also a research hotspot in the field of flotation colloid chemistry in recent years.To understand the underlying mechanism of flotation,the recent development in the interaction force between bubble and particle and the hydrodynamic drainage models of the thin liquid film were reviewed systematically.For the interaction force,the hydrophobic force is the fundamental driving force overcoming the repulsive DLVO force between bubble and particle,inducing successful attachment.The origin mechanism of the hydrophobic force is not the same at different regimes.The long ranged hydrophobic force (>20 nm) is mainly attributed to the bridge of submicron bubbles or nano bubbles,while the short ranged hydrophobic force (<20 nm) is mainly attributed to the re arrangement of the interfacial water molecules.Due to the strong attraction characteristics of the hydrophobic force and the deformation effect of the gas liquid interface,the quantitative characterization of the hydrophobic force between bubble and particle is experimentally challenging.For the hydrodynamic drainage model,the most representatives are Stef an Reynolds model,Taylor model,and the Stokes Reynolds Young Laplace (SRYL) model.Variations in bubble surface curvature during film thinning are not taken into consideration in Stefan Reynolds and Taylor models,and hence their applications have great limitation.However,the SRYL model describes not only the film thinning dynamics between bubble and particle,but also the air water interface deformation under surface forces and hydrodynamic force.Under a given initial and boundary condition,the force information can be obtained through iterative method when the theoretical film profile is consistent with experimental results.Also the film drainage profile could be obtained using SRYL model by comparing with experimental force results.In the future investigations,SRYL model should be combined with experimental tests to quantify the hydrophobic force between bubble and particle,revealing the mechanism of flotation attachment.