Supported optically active poly(amide-imide) on magnetic graphene oxide/Fe 3 O 4 for Hg 2+ adsorption from aqueous solution

The ternary superparamagnetic nanocomposites consisting of graphene oxide (GO), Fe 3 O 4 nanoparticles, and optically active poly(amide-imide) (PAI) were fabricated in three steps consisting of a facile one-pot in situ growth of Fe 3 O 4 on GO, resulted in the preparation of the magnetic Fe 3 O 4 @GO, modification of Fe 3 O 4 @GO by 3-aminopropyltriethoxy silane to introduce amino groups on its surface, and subsequently its compositing by various levels of 5, 10, and 15 wt% with chiral PAI derived from 3,5-diamino- N-(4-(di(1H-indol-3-yl)methyl)phenyl)benzamide and N, N′-(4,4′-carbonyldiphthaloyl)-bis-l-phenylalanine diacid through ultrasonic irradiation. Characterization of the resulting nanocomposites was performed by Fourier transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometer, scanning electron microscope (SEM), and thermogravimetric analysis (TGA). The SEM analysis showed Fe 3 O 4 nanoparticles with 30 nm size successfully decorated the GO nanosheets. The TGA analysis established the expected thermal stabilities for PAI/Fe 3 O 4 @GO nanocomposites. Furthermore, incorporation of Fe 3 O 4 @GO in polymer matrix improved the mechanical properties substantially. PAI/Fe 3 O 4 @GO 10 wt% was used to evaluate the sorption properties of Hg 2+ at pH 7.