EFFECTS OF SURFACTANTS ON THE PRECIPITATION AND PROPERTIES OF COLLOIDAL PARTICLES FROM FORCED HYDROLYSIS OF FECL3-HCL SOLUTION

The forced hydrolysis of FeCl3-HCl solution in the presence of surfactants such as sodium dodecyl sulphate (SDS), cetyltrimethyl ammonium chloride (CTAC), polyoxyethylene (20) nonylphenyl ether (NP-20) and po ly(oxyethylene-oxypropylene) (PE-64) has been carried out and the precipitated particles were characterized by various techniques. No effect on the morphology of the precipitates was observed for CTAC and NP-20. The addition of a small amount of PE-64 progressed the particle growth but PE-64 yielded small lemon-shape alpha-Fe2O3 particles at high concentration. On the other hand, the morphological uniformity of alpha-Fe2O3 particles was impaired and they changed to needle- or rod-like alpha-FeOOH particles with increase in the SDS concentration. The alpha-Fe2O3 particles formed with SDS showed a high selective adsorption of H2O and CO2, although alpha-FeOOH particles have no such selectivity. The alpha-FeOOH particles thus prepared exhibited a low porosity on the heat treatment in vacuo.