• ETRI Journal
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• v.26 no.3
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• pp.252-256
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• 2004

We formed silver nanocrystallites by the thermal decomposition of a $Ag^{+1}$-oleate complex, which was prepared by a reaction with $AgNO_{3}$ and sodium oleate in a water solution. The resulting monodispersed silver nanocrystallites were produced by controlling the temperature (290$^{\circ}$C). Transmission electron microscopic (TEM) images of the particles showed a 2-dimensional assembly of the particles with a diameter of $9.5{\pm}0.7nm$, demonstrating the uniformity of these nanocrystallites. An energy-dispersive X-ray (EDX) spectrum and X-ray diffraction (XRD) peaks of the nanocrystallites showed the highly crystalline nature of the silver structure. We analyzed the decomposition of the $Ag^{+1}$-oleate complex using a Thermo Gravimetric Analyzer (TGA) and observed the crystallization process using XRD.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.389-396
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• 1991

The pre-concentration and determination of ultratrace arsenic in water samples was studied by the precipitate flotation technique. The arsenic in 1.0l of water sample, in which all suspended materials were filtered out, was coprecipitated together with La(OH)$_3$ precipitates at pH 8.5${\pm}$0.1. After the precipitate was made to be hydrophobic by adding mixed surfactant of 1 : 8 mole ratio of sodium oleate and sodium dodecyl sulfate, it was floated with the aid of tiny bubbles of nitrogen gas in a flotation cell. The floated precipitate was quantitatively collected on a micropore glass filter by the suction, dissolved with small volume of 1.0M sulfuric acid, and accurately diluted to 25.00ml with a de-ionized water. Total arsenic was spectrophotometrically determinated by forming silver diethyldithiocarbamate complex of arsine generated from arsenic in the concentrated solution. The calibration curve was linear up to 20ng/ml in the original solution. Analytical results showed that contents of arsenic in a campus wastewater and a river water were 8.2ng/ml and l.0ng/ml, respectively, and their recoveries were 93${\%}$ and 90${\%}$ in water samples which a given amount of arsenic was added into. From above result, it could be concluded that this method was applicable to the determination of arsenic in various kinds of water at low ng/ml levels.