海绵钛中氯含量测定的离子色谱分析方法

氯影响钛基材料性能，目前海绵钛中氯的测定方法存在着流程长、需要的试剂多或只可定性，无法定量等问题。本文将离子色谱法用于海绵钛中氯的测定，通过海绵钛试样处理方法研究、去除钛离子效果分析、梯度淋洗程序的确定、抗干扰实验等，考察了溶剂、酸度及色谱条件对测定结果的影响，优化了色谱条件，解决了氯与钛基体难以分离的技术难题，建立了海绵钛中氯量测定的离子色谱法。研究发现，氢氟酸会影响H型阳离子交换前处理柱（简称H柱）的使用效果；处理后的海绵钛溶液需先稀释而后过滤，这样除去重金属的效果较好；硫酸-硝酸处理海绵钛在加入硝酸后须加热去除二氧化氮；随着色谱柱使用时间变长，柱效降低，Cl^-与SO₄^2-及NO₃^-分离度降低，可通过改变梯度淋洗程序改善分离效果。使用H柱除去钛阳离子；采用梯度淋洗程序，以KOH溶液（1.0 mL/min）淋洗液，用抑制性电导检测，外标法定量测定氯。测定线性范围为0.005～2.0 μg/mL，检出限和定量检测下限分别为0.0039和0.013 μg/mL，相对标准偏差（RSD）不大于5.0%，样品加标回收率94%～110%，可以分析海绵钛中0.005%～2.0%的氯，较国标GB/T 4698.25-2017的测定范围0.010%～0.40%宽，测定结果与国标光度法吻合较好，可满足海绵钛中氯含量测定的要求。

Ion Chromatographic Method for the Determination of Chlorine Content in Titanium Sponge

Chlorine affects the properties of titanium-based materials. At present， the problems are that the analytical process of chlorine in titanium sponge is long， many reagents are required， and it is only qualitative. In this study， ion chromatography method was used for the determination of chlorine in titanium sponge. Through the study of the treatment method of titanium sponge， analysis of titanium removal effect， determination of gradient elution procedure， anti-jamming experiments， etc.， the effects of solvents， acidity and chromatographic conditions on the results were investigated， the chromatographic conditions were optimized， and the difficult technical problem of separating chlorine from titanium matrix was solved. An ion chromatography method for the chlorine content in titanium sponge was established. It is found that ①Hydrofluoric acid will affect the application effect of H-type cation exchange pretreatment column （H column for short）； ②The treated sponge titanium solution needs to be diluted first and then filtered， so the effect of removing heavy metals is better； ③After adding nitric acid， sponge titanium treated with sulfuric acid nitric acid must be heated to drive away nitrogen dioxide； ④As the use time of chromatographic column becomes longer， the column efficiency decreases， and the resolution of Cl^- with \mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} and \mathrm{N}{\mathrm{O}}_{\mathrm{3}}^{-} decreases. The separation effect can be improved by changing the gradient elution procedure. H column was used to remove titanium cations； The gradient elution procedure was used to elute the solution with KOH solution （1.0 mL/min）， the inhibitory conductivity detection was used， and the chlorine was quantitatively determined by external standard method. The limit of detection and limit of quantification of the methods are 0.0039 μg/mL and 0.013 μg/mL， respectively. The relative standard deviation （RSD） is not more than 5.0%， and the recovery of standard addition is 94%~110%. It can analyze 0.005%~2.0% chlorine in titanium sponge. It is wider than that of the national standard GB/T 4698.25-2017 （0.010%~0.40%）， and the results are in good agreement with those of the national standard photometry， which can meet the requirements of the determination of chlorine content in titanium sponge.