Use of an automated tension cell to measure physical properties of colloidal systems

Abstract

A tension cell device is described which is able to automatically collect outflow data and maintain constant loads (2 cm to 18 cm 1-120 ) for flow systems involving water saturated, deformable porous media. Using the theoretical apparatus presently available for analyzing such systems, various flow parameters are obtained: k, permeability; ce, coefficient of bulk compressibility; and Din, the material diffusivity. The flow parameters are a function of a variety of structural factors, which are controlled to a large extent by the nature of the forces operating between particles. Thus, the values for k, ce and D m are applied to the problem of understanding structure in relatively dilute colloidal systems. Two different aluminum hydroxycarbonate materials are examined, each having a pH dependent surface charge but different in surface area. Because of their particular properties, structural differences between cohesive particle networks (occurring at the point of zero charge (pzc)) and swelling type systems (at pH values much different than pzc) may be examined.