Polyamidoamine dendrimers functionalized magnetic carbon nanotubes as an efficient adsorbent for the separation of flavonoids from plant extraction

Abstract

In this study, amine terminated polyamidoamine dendrimer (PAMAM)-functionalized magnetic multi-walled carbon nanotubes (PAMAM@MCNTs) were prepared as an efficient adsorbent for the separation of flavonoids from plant extraction. The obtained PAMAM@MCNT nanoadsorbents were characterized in detail. Rutin was chosen as a model molecule of flavonoids to investigate the adsorption efficiency of PAMAM@MCNTs. The main influences of several parameters, including contact time, initial solution concentration, pH value, and temperature, were optimized to determine the optimum adsorption conditions. Furthermore, the adsorption kinetic and isotherm models were performed to elucidate the adsorption process. The results showed that PAMAM and Fe3O4 were successfully grafted to the surface of carboxylated CNTs (CNTs-COOH) by characterization via several techniques, such as scanning electron microscopy (SEM), X-ray diffraction spectrometry, vibrating sample magnetometry, and Fourier transform infrared spectra. The PAMAM@MCNTs exhibited high efficiency for the rutin at solution pH = 8.0 and room temperature. Adsorption process could be effectively described by Langmuir adsorption isotherm, and the maximum adsorption capacity was calculated as 56.48 mg/g, whereas a pseudo-second-order model was suitable to explain the kinetics of adsorption. The PAMAM@MCNTs can be effectively regenerated by alkaline dimethyl sulfoxide and reused to at least threefold. Moreover, PAMAM@MCNTs demonstrated potential in various applications as an efficient adsorbent for separating flavonoids from plant extraction. The above-mentioned results provided references for further separation of bioactive components from plant extracts using magnetic nanomaterials.