凹凸棒土应用于水样中铜和铅测定的研究

Study on the application of attapulgite to determination of Cu(Ⅱ)and Pb(Ⅱ)in water samples

本文以凹凸棒土为固相萃取剂,与火焰原子吸收光谱(FAAS)法联用,富集并检测样品中的痕量金属离子。研究了凹凸棒土对痕量Cu(Ⅱ)和Pb(Ⅱ)的吸附作用,考察了吸附时间、凹凸棒土加入量等影响其吸附和解吸的主要因素、并考察了静态饱和吸附容量,及共存离子的影响。结果表明,当pH 6.0、凹凸棒土用量为0.25 g时,凹凸棒土对Cu(Ⅱ)和Pb(Ⅱ)的吸附率达到90.3%和92.1%;用20 mL 0.1 mol.L-1的HNO3可将吸附在凹凸棒土上的Cu(Ⅱ)和Pb(Ⅱ)定量洗脱。凹凸棒土对Cu(Ⅱ)和Pb(Ⅱ)的静态饱和吸附容量分别为15.8 mg.g-1、23.7 mg.g-1;本法对Cu(Ⅱ)和Pb(Ⅱ)的检出限分别为2.80μg.L-1、0.25μg.L-1;相对标准偏差分别为1.9%和2.1%(Cu(Ⅱ)、Pb(Ⅱ):0.40μg.mL-1,n=5)。在优化的实验条件下,实测了水样中Cu(Ⅱ)和Pb(Ⅱ)的含量,加标回收率均在96%～105%之间,结果令人满意。

A method was established to determine the content of trace Cu（ Ⅱ）and Pb（ Ⅱ ）by combining enrichment and separation of attapulgite with flame atomic absorption spectrometry（FAAS） in this paper. The absorptive behavior of attapulgite to Cu（Ⅱ ）and Pb（ Ⅱ）was discussed while some problems were studied, including the static saturated adsorption capacity, the main factors influen- cing absorption and desorption,and the interference of coexisting ions. The absorption rates of Cu（ Ⅱ ）and Pb（Ⅱ）by 0. 25 g of at- tapulgite were 90. 3%and 92. 1%at pH 6. 0 and the metal ions could be quantitatively eluted from attapulgite with 20 mL of HNO3 （0. lmol· L-1 ）. Under the optimum conditions,the maximum static absorption capacity of attapulgite to Cu（ Ⅱ）and Pb（ Ⅱ ）were 15.8 mg · g-1 and 23.7 mg · g-1;the detection limits were 2. 80 μg · L-land 0.25μg · L-1 ;the relative standard deviations（RSD） were 1.9% and 2. 1% （Cu （ Ⅱ） ,Pb （Ⅱ） ：0.40 μg · mL-1, n = 5 ）. The method was applied to the determination of Cu （ Ⅱ ）and Pb （Ⅱ ） in water samples. The recoveries were 96% -105%.