Supported optically active poly(amide-imide) on magnetic graphene oxide/Fe3O4 for Hg2+ adsorption from aqueous solution

Abstract

The ternary superparamagnetic nanocomposites consisting of graphene oxide (GO), Fe3O4 nanoparticles, and optically active poly(amide-imide) (PAI) were fabricated in three steps consisting of a facile one-pot in situ growth of Fe3O4 on GO, resulted in the preparation of the magnetic Fe3O4@GO, modification of Fe3O4@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 Fe3O4 nanoparticles with 30 nm size successfully decorated the GO nanosheets. The TGA analysis established the expected thermal stabilities for PAI/Fe3O4@GO nanocomposites. Furthermore, incorporation of Fe3O4@GO in polymer matrix improved the mechanical properties substantially. PAI/Fe3O4@GO 10 wt% was used to evaluate the sorption properties of Hg2+ at pH 7.