Magnetic-responsive CNT/chitosan composite as stabilizer and adsorbent for organic contaminants and heavy metal removal

Abstract

The unprecedented development of global industrialization has accelerated the discharge of wastewater, organic pollutants and heavy metals in which pose great threats to human health and ecosystem due to their high toxicity and poor decomposition. In this work, a facile magnetic-responsive CNT/chitosan composite for multiple contaminants removal was constructed through a two-step approach, which exhibits impressive adsorption capacity toward organic contaminants and heavy metals, the adsorbed composite can be conveniently collected by applying an external magnetic field. Surface morphology and microstructure of the fabricated CNT/chitosan composite were characterized using scanning electron microscopy, scanning electron cryomicroscopy, and transmission electron microscopy. Fourier transform infrared spectroscopy, zeta potential, Thermogravimetric analysis, and X-ray diffraction were employed to investigate the modification mechanism and the interaction within the functional groups; the magnetic responsiveness of the composite is verified by the vibrating sample magnetometer. The prepared composite displayed better adsorption to organic Rhodamine B than to methyl orange due to the strong π-π electron-donor-acceptor interaction between the benzene ring of RhB and CNT. The adsorption capacity for heavy metals followed the order Fe3+>Cu2+>Pb2+>Zn2+, the organic contaminants and heavy metals removal by CNT/chitosan composite fit the pseudo-second-order kinetic model well, the preferable adsorption could be ascribed to the synergy of the π–π stacking and hydrophobic interaction of CNT and chelation interaction of chitosan. Recyclability of CNT/chitosan composite displays its great potential in multiple contaminants elimination from aqueous solutions.