Stable Suspension of Mixed Iron Oxide/Manganese Oxide Nanoparticles in Aqueous Surfactant Solutions and Their Use for Mixer Studies in Liquids Feeds

Nanoparticles combining iron oxide (higher 92%) and manganese oxide (below 8%) have been prepared by mixing aqueous solutions of ferrous sulfate, ferric chloride, manganese chloride and ammonium hydroxide following by continued stirring and heating the forming colloidal Mn-containing magnetite. After addition of oleic acid solution in heptane and stirring the upper organic layer was drawn off and formed ferromagnetic liquid was dispersed in 4% aqueous solution of ammonium oleate. This leads to preparation of stable suspension of nanoparticles with medium size below 90 nm. The content of manganese in prepared samples (about 80mg /liter) was evaluated by spectrophotometric analysis of ferromagnetic material retrieved from suspension by neodymium magnet and dissolved in hydrochloric acid. For determination of Mn- concentration the mixture of ferrous chloride and manganese chloride was oxidized by potassium periodate and absorbance at 526 nm  was measured.  Results for testing prepared suspension of mixed iron oxide/manganese oxide nanoparticles as tracers for evaluation of mixer efficiency for liquid animal feed will be discussed.