Thermal decomposition of beta-FeOOH

beta-FeOOH particles were prepared by a forced hydrolysis of the 0.1 M FeCl3 + 5(.)10(-3) M HCl solution, whereas sulfated beta-FeOOH particles were prepared by forced hydrolysis of the 0.1 M FeCl3 solution containing 5.10(-3) M quinine hydrogen sulfate (QHS). beta-FeOOH particles, as well as sulfated beta-FeOOH particles, were thermally treated up to 600 degreesC. The samples were characterized using DTA, XRD, FTIR and TEM. beta-FeOOH particles showed a cigar-type morphology, whereas bundles of beta-FeOOH needles were obtained in the presence of QHS. Heating of beta-FeOOH particles at 300 degreesC and above yielded alpha-Fe2O3 particles. Specific adsorption of sulfate groups showed a strong effect on the thermal decomposition of beta-FeOOH particles. Upon heating of sulfated particles between 300 and 500 degreesC the formation of an amorphous phase and a small fraction of alpha-Fe2O3 were observed. Needle-like morphology of amorphous particles in these samples was preserved. At 600 degreesC, alpha-Fe2O3 particles were obtained; however, they were much smaller than those obtained by heating a pure beta-FeOOH. (C) 2003 Elsevier B.V All rights reserved.