Flocculation of SDS micelles with Fe3+

This paper describes the behaviour of Fe3+ as an alternative to Al3+ in adsorptive micellar flocculation (AMF), using SDS as surfactant. The results indicate that the more acidic solutions of Fe3+ (pH around 2) present a number of setbacks when compared with those of Al3+ (pH around 3): long term contact with the surfactant hydrolyses it, the minimum Fe3+ concentration is higher, and also higher is the residual SDS concentration. The fact that sufficiently high concentrations of pollutant may cause considerable disruption of AMF when Fe3+ is the flocculant as suggested an interesting alternative which is tentatively described: the use of surfactant below its Kraft point. Compounds with acidity constants significantly higher than the pH of the solution, like phenol, are not removed by Fe3+ flocculates, although they are removed to a significant extent by Al3+ flocculates.