Surfactant modified walnut sawdust as an alternative green support for efficient preconcentration of nickel ions from different real samples

A simple and relatively selective solid phase extraction system has been described and used for determination of trace amounts of Ni(II) ions in water, soil and split peas by sodium dodecyl sulfate (SDS)-coated microparticles of walnut sawdust modified with dimethylglyoxim. Scanning electron microscopy (SEM) and Fourier transformed infrared (FT-IR) techniques were used for characterization of the sorbent. Adsorption experiments were carried out using batch mode under various operating conditions. The effect of pH, contact time, ionic strength, volume and concentration of the eluent on the Ni(II) preconcentration were studied. The equilibrium time was found to be 30 min and the adsorbed ions were stripped from the solid phase by 10 mL of 3 mol L-1 nitric acid. The eluting solution was analyzed for the Ni(II) content by flame atomic absorption spectrometry (FAAS). The adsorption data were measured at room temperature and the yielded Langmuir monolayer capacity was 22.0 mg g(-1). The detection limit (LOD) and the relative standard deviation were 0.55 mu g L-1 and 3.1% (n = 5, concentration = 0.1 mg L-1), respectively. The accuracy of the method was examined with the determination of nickel ions in a certified reference material (CRM TMDW-500, drinking water).