The properties of FeOOH precipitates formed in CTAB-rich FeCl3 solutions at various pH and ethanol contents

Abstract

Iron oxyhydroxides as an important adsorbent, catalyzer, or electrode material can be commonly prepared in surfactant-rich ferric solutions. Herein in this work, we investigated influences of pH and the ethanol/water volume ratio on iron precipitates produced in FeCl3 solutions with cetyltrimethyl ammonium bromide (CTAB) at 40 °C. The resulting iron oxyhydroxides were characterized and their properties were also analyzed. Results consistently indicated that mineral phases and crystallinities of the products in CTAB-rich FeCl3 solutions were mainly influenced by pH, and the unstable phase of ferrihydrite was favorable to transform to goethite as the pH values increased. Ethanol addition could have a negative impact on phases and crystallinities of the formed iron oxyhydroxides and also inhibit aggregation of the product particles resulting from CTAB action. Differences in particle morphologies and sizes could be mainly attributed to phases and crystallinities of the formed FeOOH, as well as presence of CTAB and ethanol.