Silver modified magnetic carbon nanotubes composite as a selective solid phase extractor for preconcentration and determination of trace mercury ions in water solution

摘要

A magnetic composite of silver/iron oxides/carbon nanotubes (Ag/Fe_3O_4/CNTs) was synthesized and used as an adsorbent for the preconcentration of mercury ions in water solutions at room temperature (25℃) in this study. The silver nanoparticles were supported on the magnetic CNTs. The modification enabled the composite had not only a high adsorption capacity for mercury ions (Hg~(2+)) but also the magnetic isolation properties. A fast, sensitive, and simple method was successfully developed for the preconcentration and determination of trace amount of Hg~(2+) in water using the synthesized nanocomposite as adsorbent. The mercury concentration was determined by an atomic fluorescence spectrometer (AFS). The experimental conditions such as pH value, extraction temperature, extraction time, sample volume, eluent composition and concentration, sorbent amount, and coexisting ions were investigated for the optimization. A 500 mL of sample volume resulted in a preconcentration factor of 125. When a 200 mL of sample was employed, the limit of detection for Hg~(2+) was as low as 0.03 ng mL~(-1)with relative standard deviation of 4.4% at 0.1 ng mL~(-1) (n = 7). The ease of synthesis and separation, the good adsorption capacity, and the satisfactory recovery will possibly make the composite an attractive adsorbent for the preconcentration of ultratrace Hg~(2+) in waters.