engleski

The impact of dextran sulfate on the radiolytic synthesis of magnetic iron oxide nanoparticles

Iron(III) chloride deoxygenated alkaline aqueous colloidal solutions in the presence of 2-propanol and dextran sulfate were γ- irradiated with doses of 36 and 130 kGy. The dose rate was ∼31 kGy h−1. The samples isolated by washing with water mainly consisted of γ- FeOOH (lepidocrocite), δ-FeOOH and schwertmannite. The samples isolated by washing with ethanol contained mainly α-FeOOH (goethite), δ-FeOOH (feroxyhyte) and iron(III) hydroxide sulfate. At lower dose (36 kGy) magnetite (Fe3O4) was formed. The samples isolated by admixing glycerol consisted of the intermediate phases Fe(OH)2, GR(SO42−) and non- stoichiometric FeS1-x (mineral name mackinawite). The amounts of Fe(II) in glycerol-isolated solid samples were 60.5% and 82.6% as determined by Mössbauer spectroscopy at doses of 36 and 130 kGy, respectively. The amount of Fe2+ in the acidified solutions containing dissolved γ-irradiation products was determined using potassium permanganate titration. The amounts of Fe2+ in acidified solutions were 72.0% and 92.0% at doses of 36 and 130 kGy, respectively. Thus, although the conventionally isolated powders consisted exclusively of Fe(III) products, the high reducing conditions upon γ-irradiation were confirmed by capturing the Fe(II) intermediate phases and by quantitative determinations of ferrous ions in the solid samples and solutions containing dissolved γ-irradiation products.

iron oxides ; gamma-irradiation ; dextran sulfate ; green rust ; iron(II) hydroxide ; feroxyhyte ; mackinawite

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