Adsorption performance of carboxylated multi-wall carbon nanotube-Fe3O4 magnetic hybrids for Cu(II) in water

Carboxylated multi-wall carbon nanotube (c-MWCNT)-Fe3O4 magnetic hybrids (c-MWCNTMCs) were prepared by mixing FeCl3·6H2O, sodium acetate, ethylene glycol and diethylene glycol with c-MWCNTs, followed by sonicating and heat treatment at 200 °C for 10 h. Results indicated that the c-MWCNTMCs showed a good dispersion stability, an acid and alkali resistivity, and magnetic properties in deionized water, and can be used as adsorbents for Cu(II) removal. The c-MWCNTMCs could be easily separated from water by a magnet and showed a high adsorption capacity for Cu(II). The adsorption of Cu(II) on the c-MWCNTMCs was quick and followed a pseudo-second-order model. The adsorption force between the c-MWCNTMCs and Cu(II) was of a chemical type and the saturated adsorbents can be regenerated at pH < 2.0. The magnetic Fe3O4 favored only the quick separation and had little contribution to adsorption. The low limit of Cu(II) in water that was removable with the hybrids was 1.29 μg/L.