Sedimentation Volume and Viscosity of Pure Clay Minerals and their Mixtures as Influenced by the Addition of Quaternary Ammonium Compounds

In view of the high adsorbability of quaternary ammonium compounds by the colloidal clays the interaction between them as been studied in considerable details particularly in relation to: (i)absorption, (ii) stability of the colloidal clays, (iii) electrochemical and electrokinetic properties, (iv) sedimentation volume, and (v) viscosity changes. Large-sixe alkyl quaternary ammonium molecules arc absorbed as such in addition to those that enter by exchange reactions. The smaller quaternary cations behave in the same way as the inorganic cations. The sedimentation volume of the clay minerals attains a maximum value (MSV) at a concentra­tion of quaternary ammonium compounds equivalent to 75-80% of the bale change capacity of the clay. Further addition after the maximum leads to charge-reversal as shown by the zeta potential measurements. At this point the flocculated mass begins to deflocculate. The value of MW follow the order: montanorilonite>illite> mica> kaolinite. For a binary mixture of kaolinite and montmorillonite, MSV is propor­tional to the content of montmorillonite. The viscosity of aqueous clay suspensions increases on the addition of quaternary ammonium compounds reaching a maximum corresponding to nearly 80% b.e.c. The possibility of separation of binary mixture, of clay minerals based on the above observation' has been indicated