萃取-分光光度法测定污水中汞的研究

Extraction-spectrophotometric determination of trace mercury in water samples

研究了萃取分光光度法测定污水中的汞．考察了萃取剂的种类、酸度及萃取试剂体积等因素对萃取率的影响。在pH为3．7的甲酸甲酸钠缓冲溶液中，HgI4^2-和[Fe（phen）3]^2＋以1：1的络合比络合生成具有较大疏水性的化合物，用甲基异丁酮萃取后，再用分光光度法测定有机相的吸光度，从而测定汞含量。结果表明，络合体系的最大吸收波长为512nm，汞的含量在O～2．71mg·L^-1范围内呈良好线性关系，摩尔吸光系数ε为2．5×10^4L·mol^-1·cm^-1，方法的检出限为0．030mg·L^-1。对4个样品测定的相对标准偏差为3．5％～5．2％，加标回收率为93.2％～106．7％，用于污水中汞的测定，有满意的结果。

Determination of Mercury in water samples was carried out using UV-spectrophotometric method. In a media of formic acid-sodium formate buffer solution of pH 3.7,KI,Hg（ I ） and [Fe（phen）3]^2＋ formed a hydrophobic complex, which can be extracted by MIBK. The effects of solvents, volumes of MIBK and pHs on the extractability of mercury was experimentally investigated. The mercury in water samples was quantitatively determined by a UV-spectrophotometer. The mercury complex showed a maximum absorption at 512 nm of wavelength. A dynamic linear relationship of mercury was obtained between 0～2. 71 mg·L^-1 The detection limit is 0. 030 mg·L^-1. An apparent molar absorptivity of 2. 5×10^4 L·mol^-1·cm^-1 was found for the mercury complex. The recovery rate of determining four samples was obtained within 93. 2%～106. 7% and the relative standard deviation was 3. 5%～5. 2%. This method shows a potential application to determine trace mercury in water.