Size and morphology of scorodite particles synthesized using ultrasound irradiation

Abstract

The synthesis of large scorodite particles (>10 µm) at low temperature (50-70 °C) with a short reaction time (3 h) using 200 kHz ultrasound irradiation was investigated. Large scorodite particles (>10 µm) were obtained using ultrasound irradiation at 70 °C. The growth of scorodite particles was confirmed by scanning electron microscopy (SEM). The precursor agglomerated at the early stage of the synthesis using ultrasound irradiation. Ultrasound irradiation was applied to agglomerate the precursor. Large scorodite particles were synthesized without fine particles using ultrasound irradiation for a short time at the early stage of the synthesis followed by oxidation using stirring and oxygen flow without ultrasound irradiation.

Synthesis of porous γ-Fe2O3 from scorodite synthesized using ultrasound irradiation and evaluation of its battery performance

“…In contrast, we previously reported the synthesis of large polyhedral scorodite particles with high crystallinity and a size larger than 10 μm at 70 °C, which is lower temperature than that of conventional stirring, using 200 kHz ultrasound irradiation for 3 h, while oxygen (O 2 ) gas is blown into a sulfuric acid solution of pH 2.0. [11][12][13][14][15] The reason for this is that the oxidation and agglomeration effects of the 200 kHz ultrasound promoted the precursor agglomeration and reduced the number of precursors in the early stages of synthesis, and in addition, the oxidants [e.g. OH radicals (OH•) and HO 2 radicals (HO 2 •)] generated by the ultrasound irradiation promoted the precursor oxidation which relates to crystallization.…”

The effect of precursor speciation on the growth of scorodite in an atmospheric scorodite synthesis

“…In addition, the particle size of scorodite is influenced by its precursor. Larger scorodite is synthesized when the size of the precursor is increased by agglomeration [19][20][21]. Even though the precursor plays a significant role in the growth of scorodite during atmospheric scorodite synthesis, the speciation of the precursor has not been characterized.…”

Synthesis of porous γ-Fe2O3 via alkaline treatment of size controlled scorodite particles synthesized using ultrasound irradiation and its evaluation as a cathode for lithium-ion battery

“…In a previous study, we synthesized polyhedral large-sized (>10 μm) scorodite particles using oxidation [5][6][7][8][9][10][11][12][13] and agglomeration effects 14) by applying 200 kHz ultrasound irradiation at 70 °C for 3 h in a sulfuric acidic solution at pH 2.0. [15][16][17] The contribution of ultrasound irradiation to the synthesis of the large scorodite particles is due to two important factors: (i) a decrease in the number of precursor particles by the agglomeration effect of ultrasound at an early stage of the experiment, and (ii) the enhancement of crystal growth with oxidation of the precursor to nuclei by oxidants [e.g., OH radicals (OH•) and HO 2 radicals (HO 2 •)] generated during ultrasound irradiation. Thus, large scorodite particles could be synthesized by increasing the amount of solute supplied per nuclei.…”