Principles of action of polymeric flocculants

Abstract

Abstract The relationship of flocculation by water‐soluble polymers to the classical phenomena of colloid chemistry is pointed out and the contributions of electrostatic and non‐electrostatic forces are discussed. Modern flocculants have a high degree of polymerization (e.g. c. 50 000) and an extremely extended configuration when dissolved in a favourable solvent; this factor explains qualitatively some of the peculiarities of flocculation by polymers and indicates the need for rational control of their use if optimum results are to be achieved. It is concluded, however, that a quantitative theory of specific flocculant systems is not possible at present. Future developments in flocculation technology will almost certainly include introduction of cheaper or more selective flocculants, improved control through the use of auxiliary reagents and more sophisticated consideration of the surface chemistry of materials that have to be flocculated.