Ionic liquid-modified Fe3O4 nanoparticle combined with central composite design for rapid preconcentration and determination of palladium ions

In this work, magnetic Fe3O4 nanoparticles (NPs) were synthesized by ultrasonic chemical co-precipitation method. Then hydrophobic ionic liquid (IL), as a green coating agent, was deposited on the surface of synthesized NPs in order to improve their extraction capability toward Pd(II) ions as diethyldithiocarbamate (DDTC) complex. Scanning electron microscopy, thermogravimetric analysis, X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Fourier transformed infrared (FTIR) techniques were used for characterization of the adsorbent. The adsorption rate was fast and the equilibrium time was achieved within 4min due to the strong interaction of Pd-DDTC complex with the IL and the absence of internal diffusion resistance. The separation of the adsorbent from aqueous bulk was achieved after about 2min by a magnet, so no centrifugation or filtration was required. The effective parameters such as pH, concentration of ligand, amount of adsorbent, and the extraction time were inspected by using a central composite design in order to identify the most important parameters and their interactions. Under optimum conditions, the detection limit was 0.82ngmL(-1) and the relative standard deviation (n=10) was 2.8% for 100ngmL(-1) of Pd(II). The proposed method was applied for the preconcentration of Pd(II) from road dust, liver, and water samples, and it was found that the amounts of palladium ions in dust and liver samples were 104 and 8.7ngmL(-1), respectively.