A facile approach for grafting ion imprinted polymer onto magnetic multi-walled carbon nanotubes for selective removal and preconcentration of cadmium in food and wastewater samples prior to atomic spectrometric determination

A 3D Fe3O4@MWCNT-CdIIP was synthesized by the oxidizing surface of multi-walled carbon nanotubes with carboxylic acid end groups and its subsequent termination with an ion imprinted polymer. An artificial neural network manifests better predictability than the central composite design methodology for optimising the adsorption procedure. The adsorption capacity was 109 mg g-1 (2.5 times more than non-imprinted polymer) under optimized conditions (pH; 5.6, time; 15 min, concentration; 800 mu g mL-1 temperature; 25 degrees C), which was in accord with Toth isotherm. Fractal-like pseudo-second-order kinetics was found reasonably fast, with 66 % adsorption in 5 min. Solid phase extraction coupled Flame atomic absorption spectrometry method provides selective recognition towards Cd(II), with limit of detection; 1.13 mu g/L, limit of quantification; 3.21 mu g/L after preconcentration (preconcentration factor; 50) and good robustness. The developed method was applied for Cd (II) determination in food (tea, coffee, bread, tobacco, radish, spinach), water and wastewater (>99 % removal as well). Cd(II) loaded IIP was further utilized to remove anionic dyes with >95 % removal.

Automated summary

A 3D Fe3O4@MWCNT-CdIIP was synthesized by oxidizing the surface of multi-walled carbon nanotubes and then terminating it with an ion-imprinted polymer. The artificial neural network outperformed the central composite design methodology in predicting the optimal adsorption conditions. Under the optimized conditions (pH 5.6, time 15 min, concentration 800 μg/mL, temperature 25 °C), the adsorption capacity of Cd(II) was 109 mg/g (2.5 times higher than non-imprinted polymer) according to the Toth isotherm. The developed solid phase extraction method coupled with flame atomic absorption spectrometry showed selective recognition towards Cd(II), with a limit of detection of 1.13 μg/L and a limit of quantification of 3.21 μg/L after preconcentration (preconcentration factor 50), and demonstrated good robustness. The method was successfully applied to determine Cd(II) in various food samples, water, wastewater, and also showed efficient removal (>95%) of anionic dyes using Cd(II) loaded IIP.