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In this work, a hydrophilic sandwich-like graphene oxide (GO) ion-imprinted polymer (IIP) was synthesized via the surface imprinting technique to develop a dispersive magnetic solid-phase extraction method for the preconcentration of Ni(II) by flame atomic absorption spectrometry (FAAS). In this imprinted polymer, allyl-rich amines (monomer) and ethylene glycol dimethacrylate (EGDMA) (cross-linker) act as platforms for Ni(II) recognition. Most importantly, the influence of other transition metals as well as alkali/alkaline earth metals in the samples was evaluated to compare the imprinting effect between IIP and nonimprinted polymer (NIP) as a control. The IIP for Ni(II) in a binary mixture provides >99% recovery with a good selectivity coefficient, whereas NIP could not recognize a specific metal ion from competitive ions due to the absence of imprinting effect. Moreover, the introduced specific binding sites with complementary shapes and sizes for Ni(II) recognition in IIP exhibited high adsorption capacity as compared to NIP and fast chemical kinetics with a pseudo-second-order model. The ease of separation from aqueous solutions by an external magnet is facilitated due to embedded Fe 3 O 4 nanoparticles. By utilizing nonlinearized isotherm modeling, two-parameter models (Langmuir, Freundlich, and Dubinin−Radushkevich) and three-parameter models (Redlich− Peterson and Sips) were analyzed with error analysis (reduced χ 2 , residual root-mean-square error (RMSE), and sum squares error (SSE)). Additionally, the structural modifications of GO were examined by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and atomic force microscopy (AFM). No significant difference was found in FTIR spectra of IIP and NIP. Accuracy was presented by SRM and recovery studies. The synthesized sorbent possesses high recognition ability even after seven regeneration cycles, illustrating potential applications for Ni(II) determination in various food and water samples.

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In this work, magnetic multiwalled carbon nanotubes‐silica binary composite (mCNT@APS) is synthesized via amide bond and utilized for the Pb(II) adsorption from aqueous solutions in batch mode. The composite is characterized using Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and point of zero charge (pHpzc) studies. Three levels and three factorial Box–Behnken design in response surface methodology is employed to assess and optimize the effects of influential parameters: pH, initial concentration, and contact time. Using the desirability function, the obtained optimum conditions are pH 5.4, feed concentration 757 µg mL−1 and contact time 4 min. The electrostatic attraction between the active binding sites of adsorbent and Pb(II) at pHpzc < pH results in higher saturation capacity (79.69 mg g−1) in accordance with the best fitted non‐linearized Langmuir isotherm model. The pseudo‐second‐order model fits well to the kinetic data implying chemisorption of Pb(II) onto mCNT@APS. The material can be regenerated up to 15 sorption–desorption cycles using 5 mL of 1.5 M HNO3. The adsorbent exhibits excellent Pb(II) removal efficiency (>98%) from industrial effluents and tap water samples.