离子液体双水相体系分离-火焰原子吸收光谱法测定铁尾矿中铁

利用［Bmim］BF₄离子液体-NaH₂PO₄双水相萃取分离体系对铁尾矿中铁进行萃取，采用火焰原子吸收光谱法测定了样品中铁的含量。考察了盐用量、温度、pH值等因素对萃取率的影响。结果表明，该离子液体双水相体系萃取铁离子的最佳条件如下：［Bmim］BF₄离子液体为1.5 mL，NaH₂PO₄·2H₂O为3.5 g，邻二氮菲溶液为2.0 mL，控制反应温度为70 ℃，pH值为6.0。方法的线性范围为0.002～60 μg/mL，校准曲线方程为A=0.104 5ρ+0.0165 2，相关系数为0.999 8，检出限为0.008 9 μg/mL，加标回收率在95%～98%之间。方法用于实际样品分析，测得结果与电感耦合等离子体原子发射光谱法一致，相对标准偏差（RSD，n=6）为4.2%~4.5%。使用后的离子液体经NaOH处理回收，其红外谱图与使用前基本一致，表明回收的离子液体可重复使用。

Determination of iron in iron tailings by ionic liquid aqueous two-phase system separation-flame atomic absorption spectrometry

After the extraction with ［Bmim］ BF₄ ionic liquid-NaH₂PO₄ aqueous two-phase extraction system, iron in iron tailing samples was determined by flame atomic absorption spectrometry. Effects of the factors like salt consumption, temperature and pH on the extraction rate were investigated. The results showed that the opitimal condition for the extraction of iron ions with the ionic liquid aqueous two-phase system at pH 6.0 was as follows:［Bmim］BF₄ ionic liquid of 1.5 mL, NaH₂PO₄·2H₂O of 3.5 g, phenanthroline solution of 2.0 mL and reaction temperature of 70 ℃. The linear range of this method was 0.002-60 μg/mL. The calibration curve equation was A=0.104 5ρ+0.0165 2 with correlation coefficient of 0.999 8. The detection limit was 0.008 9 μg/mL, and the recoveries were 95%-98%. This method was used for real sample analysis, and the results were consistent with those obtained by inductive coupling plasma atomic emission spectrometry with relative standard deviation (RSD, n=6) of 4.2%-4.5%. The ionic liquids after use was recovered by NaOH treatment, and it was found that its IR spectrum was basically the same as that before use, indicating that the recovered ionic liquid could be reused.