Rational design of ordered porous nanoparticles for selective extraction of nitrobenzene compounds

The presence of nitrobenzene compounds (NBCs) in the environment has imparted severe threats to public health. Herein, highly selective extraction of polar NBCs from aqueous samples is achieved by rational design of novel extractants. The extraction efficiencies to NBCs are much higher than other analytes (e.g., BTEX, phenols) with subtle differences in structures and molecular dimensions. This extractant (termed as PF-CROSS) was designed by constructing micropores in nanoparticles and reserving electron-donating phenolic hydroxyl groups within the hydrophobic cavities. Owing to the shielding of the phenolic hydroxyl groups from water by the hydrophobic cavities, the polar interactions and 7C-7C electron donor-acceptor specific interactions between the NBCs and PF-CROSS presented, which were confirmed based on Fourier transform infrared (FTIR) spectroscopy, and were further demonstrated to play important roles in selective extraction of NBCs through theoretical modeling. Moreover, the steric effect provided by the micropores further enhanced the extraction selectivity. By fabricating PF-CROSS into solid-phase microextraction fibers, the detection limits of developed method reached as low as 0.32-5.39 ng L-1 for NBCs in water samples. This study provides an efficient and cost-effective extraction phase for highly sensitive detection of NBCs, which is also promising for the recycling of NBCs in the future.