Abstract
The dispersion-flocculation behavior and the rheological properties of bentonite-water systems were measured on samples adjusted at different pH levels. The cation composition of equilibrium solution was also analyzed. The technique described in the previous paper was applied to estimste the probability of the existence of each interparticle linkage mode. The experimental results were interpreted in relation to the estimated existence of the particle linkage moles. The results were as follows:
1. In the sedimentation measurements, no linkage, EE (edge to edge) +EF (edge to face) linkage, EF linkage only were expected to exist at the ranges of >pH 9. 2, from pH 6. 7 to pH 9. 2 and <pH 6. 7, respectively. The impossibility of FF (face to face) linkage was expected.
2. With no linkage, the systems showed the dispersed state. In the presence of EE-FEF linkage, the systems showed flocculation.
3. The particle size fractions of <2μm, the 2-10μm and the 10-20μm dominated in the presence of no linkage (>pH 9. 2), EE-FEF linkage (between pHs 6. 7 to 8. 9) and EE linkage (<pH 6), respectively.
4. The plastic viscosity showed its maximum value under the conditions of no linkages of any kind (>pH 9. 2), and decreased adruptly between pHs of 9 and 7 with the appearance of EF linkage. The parameters of rigidity showed their maximum value in the presence of EF linkage (<pH 7), and decreased significantly with the decrease of the number of EF linkages.
In conclusion, experimental results were explained successfully by the concept of the expected existing modes of interparticle linkages. Therefore, the double layer theory and the hetero-coagulation theory applied in this manner were revealed to be useful in the semi-quantitative understanding of the dispersion-flocculation behavior and the rheological properties of bentonite water systems.
