Jarlbring Mathias, Gunneriusson Lars, Hussmann Björn, Forsling Willis
Department of Chemical Engineering and Geosciences, Division of Chemistry, Luleå University of Technology, SE-971 87 Luleå, Sweden.
J Colloid Interface Sci. 2005 May 1;285(1):212-7. doi: 10.1016/j.jcis.2004.11.005.
The acid-base properties of the maghemite (gamma-Fe2O3)/water and hematite (alpha-Fe2O3)/water interfaces have been studied by means of high precision potentiometric titrations and the experimental results are evaluated as surface complexation reactions. Synthetic maghemite and hematite were prepared and characterized using a combination of SEM, FT-IR and XRD. The specific surface area of the minerals was determined by the BET method. The titrations were performed at 25.0+/-0.2 degrees C within the range 2.8<pH<8.5, NaNO3 ionic medium giving total ionic strengths of 0.10 and 0.50 mol dm(-3) in both systems. Experimental data were evaluated using the constant capacitance model. The total proton exchange capacities of the solids were determined by saturation of the surfaces with excess acid. The number of protonated surface sites per nm2 was found to be 0.81+/-0.05 and 1.03+/-0.04 for maghemite, at I=0.10 and 0.50 mol dm(-3), respectively. The IEP for maghemite was determined from the zeta-potential using a Zetasizer 4 instrument.
通过高精度电位滴定法研究了磁赤铁矿（γ-Fe₂O₃）/水和赤铁矿（α-Fe₂O₃）/水界面的酸碱性质，并将实验结果评估为表面络合反应。制备了合成磁赤铁矿和赤铁矿，并结合扫描电子显微镜（SEM）、傅里叶变换红外光谱（FT-IR）和X射线衍射（XRD）对其进行了表征。采用BET法测定了矿物的比表面积。滴定在25.0±0.2℃下进行，pH范围为2.8<pH<8.5，在两个体系中，NaNO₃离子介质的总离子强度均为0.10和0.50 mol dm⁻³。使用恒电容模型评估实验数据。通过用过量酸使表面饱和来测定固体的总质子交换容量。在I = 0.10和0.50 mol dm⁻³时，磁赤铁矿每nm²质子化表面位点的数量分别为0.81±0.05和1.03±0.04。使用Zetasizer 4仪器通过zeta电位测定磁赤铁矿的等电点。
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