Stability of Colloidal Hematite in the Presence of Sodium Taurodeoxycholate and Sodium Dodecylsulphate

The stabilization and flocculation effects of sodium taurodeoxycholate (NaTDC) and sodium dodecylsulphate (NaDS) were investigated with a hematite dispersion. The turbidity method was used for determination of rate constants of aggregation process from which the stability coefficients were calculated. The experiments were performed in both acidic and basic media. The effect of neutral electrolyte was also examined. The electrokinetic behaviour and wettability were also investigated. The results were discussed in terms of steric contribution to the activation energy of the aggregation process. NaTDC showed effects similar to the classical ionic surfactants NaDS, the difference being in the somewhat higher NaTDC concentration required for the same effect. In the basic region both surfactants stabilized the dispersion despite the electrolyte addition, while in the acidic region charge neutralization caused the flocculation by bridging mechanism. At high surfactant concentrations the systems were completely stable despite the addition of electrolyte.