A Way of Measuring the Surface Tension of a Suspension of Bentonites

摘要

Results are presented from pendant and sessile drop measurements of the dependence of surface tension sigma of aqueous suspensions of bentonites on the period of surface formation. It is established that the sedimentation of particles is the most important factor affecting the accuracy and reproducibility of measurements of sigma in suspensions of bentonites. A procedure is proposed that neutralizes the effect this factor has on the value of sigma. Ways of measuring sigma in which sedimentation is directed differently relative to the surface are used. Sedimentation is thus directed to the surface in the pendant drop approach, and away from the surface in the sessile drop technique. Measuring sigma in these ways and averaging the results considerably reduces the error caused by sedimentation. Analysis of the concentration dependence of sigma on the suspensions of bentonite shows that the sedimentation factor is almost completely eliminated when using this procedure.