Citation: ZHU Wan-Jun, ZHAI Xiao-Ying, HUANG Ren-Yao, FENG Yong-Jun, YUAN Mao, CHEN Xu, YANG Wen-Sheng. Analysis of Trace Pb, Zn and Cu in Water Samples Based on Three-dimensional Flower-Shaped Magnesium Silicate as A Solid Sorbent and X-ray Fluorescence Spectrometry. Chinese Journal of Analytical Chemistry, 2018, 46(9): 1386-1392. doi: 10.11895/j.issn.0253-3820.181285 [复制]
Analysis of Trace Pb, Zn and Cu in Water Samples Based on Three-dimensional Flower-Shaped Magnesium Silicate as A Solid Sorbent and X-ray Fluorescence Spectrometry
X-射线荧光光谱（XRF）分析技术在自动化程度、分析成本和对环境的影响等方面具有明显优势，已被应用于现场快速检测中。但其用于直接测定水体中金属元素时，检出限过高，不能满足检测要求。本研究采用一步混合溶剂热法合成了三维花状结构硅酸镁（Three-dimensional flower-shaped magnesium silicate，3DFMS）纳米材料，以此材料作为吸附剂，选择性富集水中的Pb2+、Zn2+和Cu2+，使用便携式能量色散X射线荧光光谱（EDXRF）仪直接分析测定。通过电子显微镜、氮气吸-脱附等对3DFMS的形貌和结构进行表征，并对富集-EDXRF检测中的实验条件进行了优化。优化后的条件为：吸附剂用量为100 mg，水样体积150 mL，pH=4，吸附时间为10 min。在优化条件下，测定Pb2+、Zn2+和Cu2+的线性范围为2.0～240 μg/L，检出限分别为0.57、0.69和0.76 μg/L。对各金属离子浓度为100 μg/L的试样连续测定5次，相对标准偏差为3.8%～5.0%，用于测定实际水样中金属离子的回收率为88.0%～118.0%。本研究建立的3DFMS富集-便携式EDXRF法快速简便，无有机试剂污染，成本低，适用于水体中痕量Pb2+、Zn2+和Cu2+的现场快速检测。
X-ray fluorescence (XRF) spectrometry has been widely used for elemental analysis of a wide variety of samples due to its important features such as acceptable speed, economy and nondestructive for samples. Portable energy dispersive X-ray fluorescence spectrometry (EDXRF) is a key technology for on-site determination. However, the poor detection limits make the conventional XRF direct analysis unsatisfactory for liquid samples. Therefore, a proper pre-concentration procedure is needed to decrease the detection limit. In this study, we prepared a kind of three-dimensional flower-shaped magnesium silicate (3DFMS). Due to the high surface area, large pore size and hierarchical nanostructures, 3DFMS was employed as a solid sorbent for selective pre-concentration of Pb2+, Zn2+ and Cu2+. And then portable EDXRF was applied to directly quantify. The structure and morphology of 3DFMS were characterized by X-ray diffraction, scanning and transmission electron microscopes. The related adsorption and detect conditions have been optimized. Under the optimal conditions (100 mg of adsorbent dose, 150 mL of water, pH 4 and 10 min of sorption time), the detection limits (S/N=3) for Pb2+, Zn2+ and Cu2+ were 0.57, 0.69 and 0.76 μg/L, respectively. The linear range was 2.0-240 μg/L for three elements. Furthermore, the recovery of metal ions in the actual water sample was 88.0%-118.0%. The relative standard deviations for five successive measurements were 3.8%-5.0% for 100 μg/L metal ions. The actual water sample was also determined by the proposed method. This present method is rapid, simple, free of organic reagent pollution and low in cost, which is suitable for the rapid determination of trace lead, zinc and copper ions in water.
GB/3838-2002, Enviromental Quality Standard for Surface Water. National Standards of the People's Republic of China
地表水环境质量标准. 中华人民共和国国家标准. GB/3838-2002