Selective Separation/Preconcentration of Silver Ion in Water by Multiwalled Carbon Nanotubes Microcolumn as a Sorbent

The present paper proposes the application of multiwalled carbon nanotubes (MWCNTs) as a solid adsorbent for selective separation/preconcentration of silver(I) in water samples prior to flame atomic absorption spectrometry. The procedure is based on the solid phase extraction of Ag(I)2-mercaptobenzothiazole chelate on MWCNTs. The elution step is carried out with 5mL of 2molL(-1) HNO3 in acetone solution at a flow rate of 1.0mLmin(-1). The influences of the various analytical parameters including pH of the solution, eluent type, sample volume, flow rates of eluent, matrix ions were investigated for optimization of the presented procedure. Tests of addition/recovery for analyte ion in real samples were performed with satisfactory results. Preconcentration factor and limit of detection for Ag(I) were 160 and 0.21 mu gL(-1), respectively. The synthesized MWCNT exhibited excellent stability in eluent solution and its adsorption capacity was 5.4mg of silver per gram of sorbent. The proposed method was successfully applied to trace silver determination in a variety of environmental water samples.