Preconcentration of cobalt ions by a melamine-modified cellulose@MWCNT nanohybrid

Melamine functionalized cellulose@carbon nanotubes were prepared by the following method: (a) Cellulose was dissolved in a mixture of urea and NaOH solutions and then mixed with multiwall carbon nanotubes; (b) the MWCT-modified cellulose was precipitated by addition of water; (c) the MWCNTs were activated with thionyl chloride, and finally reacted with melamine. The resulting sorbent was used in preconcentration of Co(II) ions prior to their determination by flame atomic absorption spectroscopy. The sorbent was characterized by FTIR and field emission scanning electron microscopy. The effects of the pH value of the medium, contact time, and elution conditions were optimized. The calibration plot is linear in the 3 to 200 mu g center dot LaEuro3/4(1) Co(II) concentration range, the limit of detection is 0.8 mu g center dot LaEuro3/4(1), and the relative standard deviation (at a concentration of 100 mu g center dot LaEuro3/4(1)) is 3.5 %. The maximum sorption capacity is 167 mg center dot gaEuro3/4(1). The method was applied to the preconcentration of cobalt ions from (spiked) food and water samples and gave recoveries between 96 and 102 %.