高温裂解-离子色谱法测定煤中卤素的含量

Determination of Halogens in Coal by Ion Chromatography Coupled with High Temperature Pyrolysis Pretreatment

建立高温裂解-离子色谱联用技术检测煤中卤素含量的方法。煤样30.0~40.0 mg在350 mL·min^(-1)富氧条件下经1 100℃高温裂解处理后,含卤素组分转化成气体形式被20 mmol·L^(-1)氢氧化钠溶液5 mL吸收后,采用离子色谱电导检测器和IonPac AS18柱测定吸收液中氟、氯和溴的含量,采用离子色谱安培检测器和Ionpac AS11-HC柱测定吸收液中碘离子的含量。结果表明,氟、氯、溴和碘的质量浓度在一定范围内与其峰面积呈线性关系,检出限(3s)分别为3.03,2.47,0.80,8.85 mg·kg^(-1)。精密度试验结果显示测定值的相对标准偏差(n=9)均小于5.0%。按标准加入法对煤样进行回收试验,回收率在83.6%~105%之间。

A method was proposed for determination of the halogens in coal using high temperature pyrolysis pretreatment and ion chromatography. The coal sample （30. 0--40. 0 rag） was treated by pyrolysis at 1 100 ℃ in the oxygen of 350 mL ·min^-1 , and then the gas products of pyrolysis were absorbed in 5mL of 20 mmol · L^-1 NaOH solution. F^-, Cl^- and Br^- in the absorption solution were determined by ion chromatography with suppressed conductivity detector and IonPac AS18 column, and I^- in the absorption solution was determined by ion chromatography with integrated amperometric detector and Ionpac AS11-HC column. As shown by the results, linear relationships between values of peak area and mass concentration of F^- , Cl^- , Br^- and I^- were found in definite ranges, with detection limts （3s） of 3.03 mg · kg^-1 for F^-, 2.47 mg · kg^-1 for Cl^-, 0. 80 mg · kg^-1 for Br^- and 8. 85 mg · kg^-1 for I-. Values of RSD （n=9） for precision test were all less than 5. 0%. Test for recovery was made by standard addition method for the coal sample, giving results in the range of 83. 6%-105%.