Extraction of polycyclic aromatic hydrocarbons with a magnetic sorbent composed of alginate, magnetite nanoparticles and multiwalled carbon nanotubes

The article describes a magnetic composite sorbent for the extraction of traces of polycyclic aromatic hydrocarbons (PAHs) from water samples. The composite was prepared by caging Fe3O4 nanoparticles (NPs) and MWCNTs into calcium alginate beads. The large surface area of the MWCNTs and their pi-interactions with the aromatic rings of PAHs obviously facilitate strong adsorption. The hydrophilicity of the calcium alginate cage, in turn, enhances the dispersibility of the sorbent in the water sample. Finally, the use of magnetic NPs facilitates a simple and fast separation of the sorbent. The composite sorbent was successfully applied to the extraction of PAHs from (spiked) water samples. PAHs were quantified by HPLC with fluorescence detection. Under optimized experimental conditions, the calibration plot is linear in the range of 5 to 50 mu ga (TM) L-1 for benzo[a]anthracene and benzo[a]pyrene, and 10 to 50 mu ga (TM) L-1 for benzo[b]fluoranthene. Other figures of merit include a limit of detection of 5 nga (TM) L-1 for benzo[a]anthracene and benzo(a)pyrene, and of 10 nga (TM) L-1 for benzo[b]fluoranthene, recoveries ranging from 92.0 to 97.7 %, and relative standard deviations of < 5 %. The method has several attractive features including an easily prepared and eco-friendly sorbent, a convenient and fast extraction procedure, and a high extraction efficiency.