1. Department of Metallurgy and Chemical Engineering, Jiyuan Vocational and Technical College, Jiyuan 459000, China; 2. Jiyuan Center for Disease Control and Prevention, Jiyuan 459000, China
摘要 Pb2+作为一种具有生物蓄积毒性的重金属离子,严重危害着环境和人体健康,微痕量Pb2+的分离富集工作一直是研究热点。固相萃取技术虽能够获得较高的富集率,但材料的制备较为繁琐,应用上受到了限制。实验利用钼酸铵作为微痕量Pb2+的沉淀剂,建立了一种以微晶酚酞作吸附剂分离富集微痕量Pb2+的方法。分别考察了钼酸铵溶液的用量、酚酞溶液用量、酸度、盐的类型及用量、吸附温度、吸附时间、Pb2+的初始浓度对富集率的影响。结果表明,当体系中Pb2+的含量为100 μg时,控制体系的pH=3~7,加入1.0 mL 5.0×10-4 mol/L钼酸铵溶液,1.0 g 硝酸铵,0.3 mL 70 g/L酚酞乙醇溶液,震荡摇匀后,静置10 min,Pb2+与钼酸铵反应生成的离子缔合物被定量吸附到微晶酚酞表面上,从而实现了微痕量Pb2+的分离富集。方法成功应用于合成水样中微痕量Pb2+的定量分离,富集率在95%～105%,能够满足微痕量Pb2+的分离富集要求。
Abstract：As a kind of heavy metal ion with bioaccumulation toxicity, Pb2+ is severely harmful to the environment and human health. Therefore, the separation and enrichment of trace Pb2+ has been paid much attention. Solid phase extraction technology usually can obtain high enrichment rate, but the preparation of materials is often complex,which limits its application.A method for the separation and enrichment of trace Pb2+ using microcrystalline phenolphthalein as the adsorbent was established. Ammonium molybdate was selected as the precipitant of trace Pb2+ in experiments. The effects of ammonium molybdate solution dosage, the amount of phenolphthalein solution, the acidity, the type and the amount of salt, the adsorption temperature, the adsorption time, and the initial concentration of Pb2+ on the enrichment rate were investigated. The results showed that the separation and enrichment of trace Pb2+ could be realized under the following experimental conditions: the content of Pb2+ in system was 100 μg; the pH of system was controlled at 3-7; 1.0 mL of 5.0×10-4 mol/L ammonium molybdate solution, 1.0 g of NH4NO3, and 0.3 mL of 70 g/L phenolphthalein ethanol solution were added; after shaking and standing for 10 min, the ionic associate formed by Pb2+ and ammonium molybdate could be quantitatively adsorbed on the surface of microcrystalline phenolphthalein. The proposed method was successfully applied for the quantitative separation of trace Pb2+ in the synthetic water samples, and the enrichment rates were between 95% and 105%, which could meet the separation and enrichment requirements of trace Pb2+.
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