Study of the interaction between graphene oxide and humic acid by synchrotron radiation circular dichroism spectroscopy

Abstract

Background: Graphene Oxide (GO) was a type of two-dimension carbon nanomaterial with promising environmental application due to its good soly. in water, high absorbability and catalytic activity. Humic Acid (HA) was the main component of Natural Org. Matter (NOM) in water, which could be adsorbed on the surface of GO nanosheets via 蟺-蟺 interaction and then affect the physicochem. properties of GO in aq. system. Purpose: Investigating the interaction between GO and HA would provide some insights for environmental application of GO. Methods: We employed Synchrotron Radiation CD spectroscopy (SRCD), UV-Visible spectroscopy (UV-Vis) and Fourier Transform IR spectroscopy (FTIR) to explore the interaction between GO and HA under different mass ratio of HA to GO, environmental pH and temp. Results & Conclusion: UV-Vis spectroscopy of GO-HA showed that the intensity of the absorption peak at 228 nm gradually increased when the mass ratio of HA to GO increased to 4:1 from 1:4 and the FTIR C-O stretching vibration shifted and decreased, indicating the strong 蟺-蟺 interaction and hydrogen bonding between GO and HA. GO showed a broad peak at about 240 nm in SRCD spectra which origin from its surface O-contg. functional groups, folding or curl of the nanosheets. SRCD indicated the interaction between GO and HA could change the dispersion behavior of GO and then affect CD activity of GO-HA, depending on the mass ratio of HA to GO, environmental pH and temp. GO-HA showed higher CD activity with the increased pH and decreased temp. (4掳C) due to the increase of folding state. [on SciFinder(R)]