有机-无机介孔材料分离富集痕量铅及其火焰原子吸收光谱法测定

Separation and Enrichment of Trace Amounts of Lead with Organo-inorganic Mesoporous Material and Its Determination by FAAS

以正辛胺及γ-巯丙基三乙氧基硅烷在氯化钾溶液中反应,制得一种有机-无机介孔材料,并应用于分离富集痕量铅,试验了溶液pH值、温度、洗脱条件及干扰离子对铅(Ⅱ)分离富集的影响,结果发现该材料对铅(Ⅱ)的吸附具有较高的选择性和较大的吸附容量。在pH 6.0、试验温度为(20±1)℃条件下,铅(Ⅱ)可被该材料定量吸附。其静态饱和吸附容量为26.37 mg·g^(-1)。吸附的铅(Ⅱ)可用0.2 mol·L^(-1)硝酸-0.5 mol·L^(-1)乙酸混合酸溶液洗脱,再用火焰原子吸收光谱法测定。该方法测定铅(Ⅱ)的检出限(3s/k)达到1.5μg·L^(-1),线性范围在0.80 mg·L^(-1)以内。此法应用于环境水样中痕量铅的测定,加标回收率在96.7%～105.0%之间。测定值的相对标准偏差(n=7)在1.66%～2.05%之间。

An organo-inorganic mesoporous material was prepared by the reaction of n-octylamine withγ-mercaptopropyltriethoxysilane in KCl solution,and the product obtained was used for separation and enrichment of trace amounts of Pb（Ⅱ） ions by adsorption.It was found that the organo-inorganic mesoporous material show quantitative adsorption toward Pb（Ⅱ） ion with relatively high selectivity from a solution buffered at pH 6.0 and at the temperature of（20±1）℃.The value of static saturated adsorption capacity attained to 26.37 mg·g^-1. Lead（Ⅱ） adsorbed on the mesoporous material was desorbed with a mixed solution of 0.2 mol·L^-1 HNO3 and 0.5 mol·L^-1 HOAc,and its content determined by FAAS under prescribed condition.Linear relationship between values of absorbance and mass concentration of Pb（Ⅱ） was kept in the range within 0.80 mg·L^-1,and the detection limit（3s/k） of the method was found to be 1.5μg·L.Tests for recovery and precision were made by adding standard Pb（Ⅱ） solution at 3 different concentration levels,to waste water samples and analyzed by the proposed method,values of recovery found were in the range of 96.7%to 105.0%,with values of RSD＇s（n=7） in the range of 1.66%-2.05%.