疏水力作为胶体物理化学及生物大分子体系中重要作用力,具有典型的多尺度作用程特征,其中亚稳态液膜空化气泡桥接诱发长程疏水力和固液界面水分子重排熵效应诱导短程疏水力假说占据着当前学术主流,但仍缺少系统理论研究.为进一步阐明基...疏水力作为胶体物理化学及生物大分子体系中重要作用力,具有典型的多尺度作用程特征,其中亚稳态液膜空化气泡桥接诱发长程疏水力和固液界面水分子重排熵效应诱导短程疏水力假说占据着当前学术主流,但仍缺少系统理论研究.为进一步阐明基于亚稳态液膜空化的长程疏水力作用机制,借助原子力显微镜(AFM)及分子动力学模拟对全氟辛基三氯硅烷疏水化颗粒与表面间长程疏水力进行了系统研究.AFM力测试结果表明:长程疏水力作用程随接近次数增加而逐渐增大并逐渐趋于稳定,第十次接触时进针曲线跳入黏附距离达到502.01 nm,退针曲线中观察到了预示空化气泡毛细桥断裂的台阶.此外,发现经典毛细力数学模型可以较好地拟合进针曲线,通过计算得到毛细桥体积约为0.30μm^(3),从理论角度直接验证了亚稳态液膜空化气泡毛细桥的存在.进一步借助GROM ACS(GROningen M A chine for Chemical Simulations)大尺度牵引分子动力学模拟从分子尺度探索疏水颗粒分离过程中空化气泡毛细桥产生、演化过程与力学行为的内在关联机制,结果表明:疏水颗粒从基板表面跳出分离瞬间,产生的局部压降吸引氮气分子向液膜内部扩散从而形成空化气泡毛细桥,同时,在毛细桥断裂时刻在计算弹簧势力曲线中观察到了力跳跃行为.最后研究了溶液气体含量对长程疏水力的影响规律,发现气体分子含量和空化气泡毛细桥体积增长速率与毛细桥拉伸断裂长度呈现正相关关系,进一步表明了长程疏水力的气体浓度依赖效应.基于亚稳态液膜空化的长程疏水力作用机制的揭示有助于进一步完善胶体物理化学及生物大分子间相互作用理论体系,同时对调控实际矿物浮选过程具有重要指导意义.展开更多
We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recentl...We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recently(Z.Zheng,Journal of Fluid Mechanics,950,A17,2022).Based on the assumption of vertical gravitational-capillary equilibrium,the saturation distribution and profile shape of the invading fluid can be obtained by solving a nonlinear integral-differential equation.The capillary pressure curves p_(c)(s)can then be constructed by systematically varying the injection rate.Together with the relative permeability curves k_(rn)(s)that are already obtained.One can now provide quick estimates on the overall behaviours of interfacial and unsaturated flows in vertically-heterogeneous porous layers.展开更多
two equations for the calculation of surface tension of pure liquids are derived based on statistical thermodyanics by expressing the intermolecular potential as lennard-Jones pair potential.This method is simple,accu...two equations for the calculation of surface tension of pure liquids are derived based on statistical thermodyanics by expressing the intermolecular potential as lennard-Jones pair potential.This method is simple,accurate and easy to use.The calculation results for the 22 pure liquids show that these equations are superior to the empirical forula and other theoretical equations.The average relative deviations for these two equations are within 5% and 1.5% respectively.展开更多
文摘疏水力作为胶体物理化学及生物大分子体系中重要作用力,具有典型的多尺度作用程特征,其中亚稳态液膜空化气泡桥接诱发长程疏水力和固液界面水分子重排熵效应诱导短程疏水力假说占据着当前学术主流,但仍缺少系统理论研究.为进一步阐明基于亚稳态液膜空化的长程疏水力作用机制,借助原子力显微镜(AFM)及分子动力学模拟对全氟辛基三氯硅烷疏水化颗粒与表面间长程疏水力进行了系统研究.AFM力测试结果表明:长程疏水力作用程随接近次数增加而逐渐增大并逐渐趋于稳定,第十次接触时进针曲线跳入黏附距离达到502.01 nm,退针曲线中观察到了预示空化气泡毛细桥断裂的台阶.此外,发现经典毛细力数学模型可以较好地拟合进针曲线,通过计算得到毛细桥体积约为0.30μm^(3),从理论角度直接验证了亚稳态液膜空化气泡毛细桥的存在.进一步借助GROM ACS(GROningen M A chine for Chemical Simulations)大尺度牵引分子动力学模拟从分子尺度探索疏水颗粒分离过程中空化气泡毛细桥产生、演化过程与力学行为的内在关联机制,结果表明:疏水颗粒从基板表面跳出分离瞬间,产生的局部压降吸引氮气分子向液膜内部扩散从而形成空化气泡毛细桥,同时,在毛细桥断裂时刻在计算弹簧势力曲线中观察到了力跳跃行为.最后研究了溶液气体含量对长程疏水力的影响规律,发现气体分子含量和空化气泡毛细桥体积增长速率与毛细桥拉伸断裂长度呈现正相关关系,进一步表明了长程疏水力的气体浓度依赖效应.基于亚稳态液膜空化的长程疏水力作用机制的揭示有助于进一步完善胶体物理化学及生物大分子间相互作用理论体系,同时对调控实际矿物浮选过程具有重要指导意义.
基金by the Program for Professor of Special Appointment(Eastern Scholar,No.TP2020009)at Shanghai Institutions of Higher Learning。
文摘We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recently(Z.Zheng,Journal of Fluid Mechanics,950,A17,2022).Based on the assumption of vertical gravitational-capillary equilibrium,the saturation distribution and profile shape of the invading fluid can be obtained by solving a nonlinear integral-differential equation.The capillary pressure curves p_(c)(s)can then be constructed by systematically varying the injection rate.Together with the relative permeability curves k_(rn)(s)that are already obtained.One can now provide quick estimates on the overall behaviours of interfacial and unsaturated flows in vertically-heterogeneous porous layers.
文摘two equations for the calculation of surface tension of pure liquids are derived based on statistical thermodyanics by expressing the intermolecular potential as lennard-Jones pair potential.This method is simple,accurate and easy to use.The calculation results for the 22 pure liquids show that these equations are superior to the empirical forula and other theoretical equations.The average relative deviations for these two equations are within 5% and 1.5% respectively.
