1.The dioxouranium(VI) cation (uranyl, UO 2 2+ ) can be separated and identified
ID: 853171 • Letter: 1
Question
1.The dioxouranium(VI) cation (uranyl, UO22+) can be separated and identified using the Procedure described in this experiment. The spot test results for this cation with the following test reagents are:
K4Fe(CN)6 red-brown
KSCN/acetone no reaction
DMG/NH3 pale yellow
(a)Based on these data, what would be the best test reagent for UO22+?
(b)The Rf value of UO22+ in the solvent system used in this module is 0.68. Explain which of the other cation tests used in this experiment it would interfere with, what alternate test reagent you would therefore use to identify that other cation, and which of the two tests should be performed first.
Explanation / Answer
Herein, a simple wet-chemical pathway has been demonstrated for the synthesis of silver nanoparticle conjugated reduced graphene oxide nanosheets where dimethylformamide (DMF) is judiciously employed as an efficient reducing agent. Altogether DMF reduces both silver nitrate (AgNO3) and graphene oxide (GO) in the reaction mixture. Additionally the presence of polyvinylpyrolidone (PVP) assists the nanophasic growth and homogeneous distribution of the plasmonic nanoparticle Ag (0). Reduction of graphene oxide and presence of aggregated Ag NPs on reduced graphene oxide (rGO) nanosheets are confirmed from various spectroscopic techniques. Finally the composite material has been exploited as an intriguing platform for surface enhanced Raman scattering (SERS) based selective detection of uranyl (UO22+) ion. The limit of detection has been achieved to be as low as 10 nM. Here the normal Raman spectral (NRS) band of uranyl acetate (UAc) at 838 cm-1 shifts to 714 cm-1 and 730 cm-1 as SERS bands for pH 5.0 and pH 12.0, respectively. This distinguished Raman shift of the symmetric streching mode for UO22+ ion is indicative of pronounced charge transfer (CT) effect. This CT effect even supports the higher sensitivity of the protocol towards UO22+ over other tested oxo-ions. It is anticipated that rGO nanosheets furnish a convenient compartment to favor the interaction between Ag NPs and UO22+ ion through proximity induced adsorption even at low concentration.
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