Abstract
Graphene oxide (GO) nano-sheets were synthesized using a modified Hummers’ method from graphite powder. The Raman spectrum of GO displayed a D-band at 1359 cm−1 and a G-band at 1594 cm−1. The ID/IG value of GO was calculated to be 0.97, suggesting the formation of new sp2 clusters upon reduction. A method was designed to investigate the assembly of the GO/montmorillonite (MMT) composite. After the addition of GO, the typical peaks of montmorillonite in FT-IR spectra shifted, indicating the assembly between GO and MMT. The D-band and G-band reduced sharply in the GO/MMT composite. More importantly, the D-band (1344 cm−1) and G-band (1574 cm−1) shifted significantly and the ID/IG value of the GO/MMT composite was calculated to be 1.13, showing a change in the GO structure. In the addition of 0.04 wt% GO to MMT, the value of interlayer space (d) was up to 13.0 Å measured by XRD due to the insertion of GO into MMT. The evident increases in contents of carbon atoms (26.59%) and nitrogen atoms (3.44%) indicate that GO was successfully combined with MMT. The nano-pores and clay sheets were not observed in the SEM image of GO/clay, but obvious wrinkles, while flexible sheets were observed in the typical scanning electron microscopy images of GO. This further proves that GO was combining with clay. The TEM image shows that the GO nano-sheets were tiled on the surface of MMT sheets. This observation suggests that a stable assembly structure was formed between GO sheets and MMT sheets. The change in particle size of MMT with the addition of GO shows that interaction occurred between GO sheets and MMT sheets, which was further confirmed by the results of zeta potential. Adsorption and insertion were the main mechanisms to assemble GO and MMT.
Highlights
With economic development and increasing demand for energy, as well as the depletion of conventional oil and gas reserves, more and more attention has been paid to unconventional oil and gas resources (Rajnauth 2012)
The graphene oxide nanosheets were adsorbed on the surface of montmorillonite
The Raman spectrum and FTIR spectra of Graphene oxide (GO)/MMT showed that interaction occurred between GO sheets and MMT sheets
Summary
With economic development and increasing demand for energy, as well as the depletion of conventional oil and gas reserves, more and more attention has been paid to unconventional oil and gas resources (Rajnauth 2012). Shale gas is considered to be an unconventional source due to shale’s typically low porosity and low permeability. Shale gas has been produced at industrial scale in the USA, and the shale gas revolution has swiftly erupted around the world. It has been estimated that the drilled formations are Edited by Yan-Hua Sun. Petroleum Science (2018) 15:366–374 segments aggravate wellbore instability during drilling shale formations due to the swelling of clay minerals. Montmorillonite is a member of the smectite group, and smectite and montmorillonite are often not distinguished. Controlling the swelling of montmorillonite is an effective solution to instability of shale formations
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