Modification of halloysite nanotubes by hydroxyl terminated triazine-based dendritic polymer for efficient adsorptive removal of Cd (II) from aqueous media

In the present study, the hydroxyl terminated triazine-based dendritic polymer was synthesized and grown on the halloysite nanotubes surface (HNT-G2) to efficiently remove the Cd (II) ions from aqueous solution. The nano-adsorbent morphology and structure were determined through transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analyzer, Brunauer-Emmett-Teller isotherm, and energy dispersive X-ray spectroscopy analysis methods. The adsorption of Cd (II) has resulted a maximum of 105.26 mg g(-1) at 298 K at optimal pH 6. As research revealed the adsorption kinetic followed the pseudo-second-order model, while the adsorption isotherms corresponded the Langmuir model. Accordingly, it could be inferred that the Cd (II) was a single-layer adsorption occurring on the adsorbent surface, and further, the rate-controlling step was denoted chemical adsorption. Also, the thermodynamic results showed that the adsorption process could occur spontaneously; therefore, it was considered as an endothermic reaction. Surprisingly, the adsorption and desorption efficiency after four cycles was high, while the Cd (II) adsorption mechanism affecting the adsorbent was basically via chelation through the O atoms. Hence, it can be concluded that the HNT-G2 was effective in efficiently removing of Cd (II) from the aqueous solution, having high applicability significance.