活性炭吸附及离子交换富集分离-分光光度法测定水中痕量银

建立了用活性炭对水中痕量银进行预富集的新方法。结果表明,pH=1.0时,活性炭能对水中被抗坏血酸还原后的痕量银进行吸附富集,而Cu(Ⅱ)、Fe(Ⅲ)、Co(Ⅱ)、Ni(Ⅱ)、Pb(Ⅱ)、Zn(Ⅱ)、Mn(Ⅱ)、Al(Ⅲ)、Bi(Ⅲ)和Sb(Ⅲ)等常见阳离子不被吸附,用K2S2O8将吸附在活性炭上的单质银氧化解脱后,用Mg(NO3)2辅助置换洗脱,可用分光光度法测定。该法在8～50μg/L银(Ⅰ)范围内加标回收率为93.2～97.1%。同时还研究了活性炭对银的吸附行为,提出了活性炭表面上被氧化的Ag(Ⅰ)和Mg(Ⅱ)有离子交换作用。应用该法测定自来水中痕量银,结果令人满意。

SEPECTROPHOMETRIC DETERMINATION OF SILVER AFTER PRECONCENTRATION OF ELEMENTAL SILVER ON ACTIVATED CARBON

A simple, accurate, sensitive and selective method was described for rapid determination of ultra-trace quantities of silver. Ag(Ⅰ) was collected on activated carbon (AC) after reduction to elemental Ag by L-ascorbic acid at pH 1.0, However, familiar metal cations, such as Cu(Ⅱ)、Fe(Ⅲ)、Co(II)、Ni(Ⅱ)、Pb(Ⅱ)、Zn(Ⅱ)、Mn(Ⅱ)、Al(Ⅲ)、Bi(Ⅲ), Sb(Ⅲ) were not adsorbed under this condition. The collected silver was oxidized by Potassium peroxydisulfate, was exchanged by Mg~(2+) in sulfuric acid media and was determined by sepectrophometer. The Enrichment of Ag(Ⅰ) was 93.2～97.1% in the concentration of 8～50μg/L. This method was used to the determination of Ag(Ⅰ) in natural water with satisfactory results. The adsorption behavior of silver on activated carbon was studied. It showed that ion-exchange of Ag~+ and Mg~(2+) was existed on the surface of oxidized activated carbon.