A Metal-Ion Adsorbent Based on Composite of Graphene Oxide/Poly (1-(3-aminopropyl) Pyrrole)

A novel metal-ion adsorbent was developed based on graphene oxide (GO) and poly (1-(3-aminopropyl) pyrrole. Firstly, GO was covalently functionalized by 1-(3-aminopropyl) pyrrole (APP) monomer by an esterification reaction between the carboxyl groups of GO and the amine groups of APP. Subsequently, a GO/poly (1-(3-aminopropyl) pyrrole) (poly (GO-APP)) composite was prepared by in situ crosslinking polymerization.

The chemical structure of poly (GO-APP) composite was determined by a series of characterization methods, such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and Thermogravimetric analysis (TGA).

The poly (GO-APP) was a hard solid material like a coal (Figure a), which is due to the crosslinked polymerization between GO and polymer. In this composite system, the GO is a crosslinking agent like a polyfunctional monomer, which can turn the linear polymer into crosslinked network polymer to increase the stiffness, strength and stability of poly (GO-APP).

This poly (GO-APP) composite is used for the adsorption of metal ions. As shown in Figure b, the absorption capacity of poly (GO-APP) was much larger than that of GO. The sorption of metal ions is based on both nitrogen and oxygen functional groups. The oxygen-containing functional groups in GO and the protonated amine groups in APP can bind to cations easily. Moreover, the chemical affinity of metal ions for amine groups is stronger than that for oxygen-containing functional groups. Therefore, the absorption capacity increases with the content of APP monomer.

Besides, the poly (GO-APP) showed a conducting property due to the conjugated π-π system in the main chain of copolymer, which will greatly expand the application fields of poly (GO-APP) composite.