研究目的
Investigating the crystallographic and magnetic changes of porous maghemite (PM) upon SO4^2? and CO3^2? adsorption.
研究成果
The electronegativity of adsorbed inorganic anions is critical for understanding their effects on the magnetic properties of PM. IAs with low electronegativity can increase Ms through decreasing surface spin disorder, while IAs with high electronegativity act oppositely. The study suggests that variation in χ is not a precise index for indicating the reaction of NFs, size distribution of NFs and IA adsorption are potential constraints.
研究不足
The study focuses on the effects of SO4^2? and CO3^2? adsorption on the magnetic properties of PM, but does not explore the effects of other inorganic anions. The magnetic changes are complex and influenced by multiple factors, including the size distribution of PM particles and the electronegativity of adsorbed anions.
1：Experimental Design and Method Selection:
A two-step calcination method was adopted to prepare PM. The first step is to prepare porous nanomagnetite by heating goethite in a reducing atmosphere. The second step involves calcining the prepared nanomagnetite under air atmosphere to oxidize all ferrous Fe.
2：Sample Selection and Data Sources:
Goethite was purchased from Zhenjiang Chemical Plant (China). Analytically pure Na2SO4 and Na2CO3 were used to prepare solutions containing each anion at 1 mol L?
3：List of Experimental Equipment and Materials:
Special homemade quartz tube, electric furnace, SGH-300 hydrogen generator, muffle furnace (SX-5-12), TEM (JEM 2100F), XRD (D/max-RB-type power diffractometer), FTIR (Bruker Vertex 70 FTIR spectrometer), XPS (Thermo Scientific ESCALAB 250Xi X-ray photoelectron spectrometer), SQUID magnetometer (Quantum Design MPMS XL-7).
4：7). Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: PM was dispersed into solutions containing SO4^2? and CO3^2?, and the magnetic susceptibilities were monitored regularly. After reaction, PM was extracted by filtration and washed with deionized water.
5：Data Analysis Methods:
XRD analysis, FTIR, TEM, XPS, and magnetic measurements were performed to analyze the crystallographic and magnetic changes of PM.
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