Sulfonatocalix[6]arene-decorated magnetite nanomaterials for the removal of organic pollutants from water

The magnetite nanoparticles (Fe 3 O 4 NPs) have been modified with p -sulfonatocalix[6]arene by two different approaches (Calix-MNPs and Calix-Si-MNPs) and were used for the removal of crystal violet dye and carbofuran pesticide as model organic pollutants from aqueous solution. The Calix-Si-MNPs showed higher adsorption capacity than Calix-MNPs, signifying the positive impact of the modification carried out on the surface of magnetite nanoparticles through a spacer. The effect of different parameters such as concentrations of pollutants, the dosage of nanoadsorbent, temperature and pH on the adsorption has been evaluated. Langmuir and Freundlich isotherm models were studied to express the equilibrium isotherms; however, the Langmuir isotherm best defined the adsorption process, indicating a monolayer adsorption. Thermodynamic parameters such as enthalpy ( Δ H ) and Gibb’s free energy (Δ G ) indicated that adsorption is endothermic and spontaneous. The kinetic studies support a pseudo-second-order kinetic model. The nanoadsorbent can be easily recovered using a magnet and can be regenerated and reused for adsorption application. Graphical abstract