Simultaneous extraction and preconcentration of Cu2+, Ni2+ and Zn2+ ions using Ag nanoparticle-loaded activated carbon: Response surface methodology

•A novel Ag-NP-AC was synthesized and characterized.•Metal ions preconcentration was significantly enhanced by combination of ultrasound and Ag-NP-AC.•RSM was used for experimental design for the adsorption of metal ions.•Novel chelation agent improve preconcentration performance.

A solid phase extraction (SPE) procedure for the simultaneous separation and preconcentration of trace amounts of nickel (Ni2+), copper (Cu2+) and Zinc (Zn2+) ions on Ag nanoparticle-loaded activated carbon(Ag-NP-AC) sorbent modified by (2-nitrobenzylidene)-2-(2-(2-nitrophenyl)imidazolidine-1-yl) ethaneamine (NBNPIEA) was applied. The chelating agents were used as efficient accumulating agents, which permit the achievement of higher selectivity following chelation. The efficient elution of retained metal ions by 5.0 mL of 2.2 mol L−1 nitric acid in acetone made it possible to monitor these analytes, accurately and repeatable from diluted and complicated matrices. Central composite design (CCD) under response surface methodology (RSM) was applied to investigate the individual and interaction effects of variables such as pH, amount of ligand, amount of Ag-NP-AC and the concentration of eluent on responses. At optimal conditions, the linear responses for Cu2+, Ni2+ and Zn2+ ions were found to be in the ranges of 0.01–0.16, 0.03–0.25 and 0.01–0.19 mg L−1, respectively. Their corresponding detection limits were found to be 3.7, 3.3 and 3.4 ng mL−1, respectively. The proposed method showed a preconcentration factor of 200, recoveries higher than 94% and reasonable relative standard deviation less than 5% with a high tolerance limit for foreign ions.

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