Preparation And Characterization Of Spinel Type Ferrite Minerals

Iron is the fourth most abundant element on Earth. Iron oxides and iron hydroxides arethe most common natural minerals. The harmful materials can be removed by the iron oxidesnanomaterials and iron hydroxides nanomaterials, which can participate in the complexformation and catalytical reactions. Therefore, it is of particular significance to explore theadsorption mechanism of iron minerals nanomaterials. Spinel ferrite nanocrystal is regardedas one of the most important inorganic nanomaterials, due to their unique physical andchemical properties, as well as technological applications in ferrofluids, biomedicine, andradar-absorbent materials.In this paper, spinel ferrite ZnFe₂O₄, NiFe₂O₄, MnFe₂O₄, CoFe₂O₄were synthesizedunder microwave irradation and characterized by X-ray diffraction （XRD）, Fouriertransforms infrared spectroscopy （FT-IR）, transmission electron microscopy （TEM）, N2adsorption-desorption measurement （BET）. The particle sizes of synthetisized ferritenanoparticles were between20-30nm and the specific surface areas were between70-200m2/g. The surface properties were studied by potentiometric titration technique. Theion-exchange model between surface fereous ions and protons in solution was establishedand the adsorption equilibrium constants were calculated by using computer softwareFITEQL. At last, ethyl xanthate was adsorbed by the spinel ferrite nanomaterals at differentpH conditions. The influence of pH on the adsorption was investigated in batch mode and theadsorption mechanism was briefly discussed. The efficiency of ethyl xanthate decreased withincreasing pH. The results provide an important reference for the surface properties of spinelferrite.In this paper, the solvothermal synthesis of L-cysteine coated Fe₃O₄nanoparticles usingFeCl₃and L-cysteine as precursors was completed. XRD, TEM, IR, and TG-DTA techniqueswere employed to characterize the morphology and structure properties of the sample. Thesurface properties were studied by performing zeta potential measurement and potentiometrictitrations. The results show that the formation of surface chemical bonds between L-cysteineand Fe₃O₄nanoparticles; the particle size of Fe₃O₄/L-Cys is between25-35nm; L-cysteine likely yields more negative charges for Fe₃O₄/L-Cys nanoparticles surface; Fe₃O₄/L-Cys pHbuffering capacity is stronger than that of Fe₃O₄.A gas sensors based on ZnFe₂O₄nanomaterial was prepared, and its gas sensitivecharacteristics to chlorinated benzene and methanol were tested. When the chlorinatedbenzene concentration is50ppm at the operating temperature of300°C, the response time is25s and the recovery time is75s. When the methanol concentration is50ppm at theoperating temperature of260°C, the response time is57s and the recovery time is62s.