Analysis of the stability behaviour of colloids obtained from different smectite clays

In stability tests, upon Na addition and consequent particle aggregation, an increase of the ζ-potential was observed, which is not in agreement with the double layer theory. Furthermore, the sample (Na)-SBId-1, which developed the highest surface potential, was the less resistant to aggregation. These results are a clear indication that the ζ-potential, alone, is not a very significant parameter to indicate or predict smectite colloid stability.