REMOVAL OF SAFRANIN FROM THE ENVIRONMENT BY USING GRAPHENE OXIDE PAPER

To

create interspace-enlarged and sites-exposed graphene-based adsorbents for

pollutant management, two-dimensional macrostructures were facilely constructed

via self-assembly of two-dimensional

graphene oxide nanosheets (2D GO). The flexible, free-standing GO paper

was prepared by vacuum filtration of GO dispersion. GO composite paper was characterized by using

Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS),

X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy.

GO paper was used as adsorbents for safranin. After the adsorption of safranin

on GO paper, it has been observed that the surface structure is very compact. Moreover, it was determined that with the

penetration of safranin between the GO layers, the distances between the plates

increased. The FTIR spectrum obtained after safranin is adsorbed on the GO, in

addition to the vibration peaks of GO, the peaks corresponding to the C=N

vibration in the phenazine ring occurred new peaks at around 1900 cm-1.

XPS spectrum of the GO paper before safranin adsorption revealed C (1s) and O (1s) peaks, while that

after adsorption exhibited the N (1s) peak beside the C (1s) and O (1s) peaks. Raman

measurements were also performed to determine the microstructure of GO paper before and after safranin adsorption. GO paper

displays two peaks at 1345 and 1650 cm-1, corresponding to the

well-documented D and G bands, respectively. The intensity ratios of the D and

G bands (ID/IG) are calculated to determine the surface

defects of graphene-based paper ID/IG for the safranin absorbed GO paper (0.75)

decreases in comparison with that of the GO paper (0.92), confirming the

adsorption of safranin species to disordered regions of GO surface. This composite paper exhibited superior adsorption

capabilities for safranin (8.1 mg cm-2). The adsorption capacity of

GO paper for safranin is higher than other two-dimensional conventional

adsorbents reported; this can be attributed to electrostatic attraction and π−π interactions between GO and

safranin. We propose a super graphene-based adsorbent that is competitive and scalable for water

purification.<o:p></o:p>