Particle Separations by Nonuniform Electric Fields in Liquid Dielectrics, Batch Methods
Particle Separations by Nonuniform Electric Fields in Liquid Dielectrics, Batch Methods
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液体电介质中非均匀电场的颗粒分离，批量方法
DOI：
10.1149/1.2427704
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发表时间：
1960
影响因子：
3.9
通讯作者：
J. P. Schwar
中科院分区：
文献类型：
--
作者：
H. A. Pohl;J. P. Schwar
液体介质中悬浮固体在非均匀电场中的运动称为介质电泳。本文报道了固体介质电泳行为的一些定量方面。在圆柱形电池中，随着施加电压的增加，析出固体的产率上升，直到达到临界电压或“脱落”电压。在1 ~ 50% v/v范围内，随着悬浮物体积分数的增加，收率降低。产率取决于电压梯度、外加电位、电池尺寸以及固体和液体的相对介电常数。在给定尺寸的粒子中，观察到产率直接依赖于介电常数。水分的影响虽小，但显而易见。正如预期的那样，介电泳行为的数量和特征与施加电场的方向无关。在此过程中观察到的电流范围可达约20 ~a，并且表明在粒子存在的情况下发生了一种新的传导方法。这是由于液体介质中通常的电流使粒子的离子充电，然后粒子通过旋转帮助电流流动和能量消耗（介电损耗）。由不均匀电场引起的悬浮固体运动称为“介电电泳”（1-3）。极性最强的物质向磁场强度最大的地方移动。与电泳不同，这种方法不需要带电粒子。相反，它取决于在非均匀场中所有极性材料所感受到的力。它可以被描述为由电场的正向和反向对粒子中产生的偶极子施加的不相等的拉力引起的。磁场的反转不会改变各向同性极化粒子的拉力方向。先前对更定量的实验方面的研究表明，场强、电极尺寸、电池尺寸和颗粒尺寸是影响圆柱形电池中中心电极保持的材料产量的重要参数。场强，电极尺寸和颗粒尺寸显示临界。在一定的上限电压、小的中心电极直径和小的颗粒尺寸下，所有的沉淀似乎都是被禁止的。这里描述的工作是对其他此类因素的持续研究。本文报道了粉末介电常数、系统干燥度、极性和粉末浓度的变化对其性能的影响。本研究中使用的仪器和处理方法基本上与前面报道的相同。由简化理论（1,2）可知，该效应应与液体介质和粉末介质的介电系数之差成正比
The motion of suspended solids in nonuniform electric fields in liquid dielectrics is called dielectrophoresis. Some of the quantitative aspects of dielectrophoretic behavior of solids is reported herein. The yield of precipitated solids is seen to rise with applied voltage in cells of cylindrical geometry, until a critical or "sluff-off" voltage is reached. The yield is seen to decrease with increase of volume fraction of suspended solids in the range of 1 to 50% v/v. The yield depends on voltage gradient, applied potential, cell dimensions, and relative dielectric constants of solid and liquid. In particles of given size, yield is observed to be directly dependent on the dielectric constant. Moisture is shown to have a small but demonstrable effect. As expected, the amount and character of dielectrophoretie behavior is observed to be independent of the direction of the field applied. Current flow during the process was observed to range up to about 20 ~a, and to indicate that a new method of conduction takes place with the particles present. It is suggested that this is due to ionic charging of the particles by usual current flow in the liquid dielectric, with the particles then aiding current flow and energy consumption (dielectric loss) by rotating. The motion of suspended solids caused by nonuniform electric fields is called "dielectrophoresis" (1-3). The most polar material moves toward the place of greatest field intensity. Unlike electrophoresis, this does not require charged particles. Instead, it depends on the force felt by all polar material when in a nonuniform field. It may be described as arising from the unequal pulls exerted by the forward and backward direction of the electric field on the dipole produced in the particle by the field. Reversal of the field produces no change in the direction of the pull on isotropically polarizable particles. Prior work on the more quantitative experimental aspects has shown that the field strength, electrode size, cell size, and particle size are important parameters affecting the yield of material held by the central electrode in a cell of cylindrical geometry. Field strength, electrode size, and particle size show criticality. At certain upper limiting voltages, small central electrode diameters, and small particle sizes, all precipitation appears to be prohibited. The work described here is a continued study of other such factors. The effects of varied dielectric constant of the powder, of the dryness of the system, of the polarity, and of the powder concentration are reported. The apparatus and handling methods used in this study are essentially those as reported earlier. Ef fec t of D ie lect r ic C o n s t a n t of the Powder As shown in the simplif ied theory ( 1 , 2 ) , the effect should be p ropor t iona l to the difference in the dielectr ic cons tan t s of the l iqu id dielectr ic and the