The Effects of Different Coagulation Conditions on the Aggregation Mechanism of Colloidal Haematite
RIS ID
55750
Abstract
In this work, both photon correlation spectroscopy and forward light scattering are used to measure the kinetics of haematite (α-Fe{2}O{3}) aggregation and flocculation which is induced by alum (Al{2} (SO{4}){3} 18H{2}O). At pH 3, the aggregation is induced by double layer compression and charge neutralisation. The critical coagulation concentration at pH 3 is about 85 ppm of alum. At pH 7, the flocculation is induced by either sweep flocculation and/or adsorption destabilisation. Aggregation kinetics induced by sweep flocculation is fast and by adsorption destabilisation is slow. The oxy-hydroxide flocs formed are fragile and can be broken up with continuous agitation to an equilibrium size which depends on the shear force applied. The oxy-hydroxide flocs can be characterised by a fractal dimension of 2.2 which is independent of the shear force applied.
Publication Details
Ng, K. W.K., Amal, R., Raper, J. & Waite, T. 1993, 'The Effects of Different Coagulation Conditions on the Aggregation Mechanism of Colloidal Haematite', Process Industries Power the Pacific Rim: Sixth Conference of the Asia Pacific Confederation of Chemical Engineering; Twenty-first Australasian Chemical Engineering Conference; Official Proceedings of Combined Conference 1993, Institution of Engineers, Australia, Barton, ACT, pp. 75-81.