• Vol 10, No 6 (2019)
  • Metalurgy and Material Engineering

Investigation of Extraction Yields of Exfoliated Graphene in Deionized Water from Organic Solvents

A Arifutzzaman, A. F. Ismail, M. Zahangir Alam, Ahsan Ali Khan, Saidur Rahman

Corresponding email: arifrahat@sunway.edu.my

Cite this article as:
Arifutzzaman, A., Ismail, A.F., Alam, M.Z., Khan, A.A., Rahman, S., 2019. Investigation of Extraction Yields of Exfoliated Graphene in Deionized Water from Organic Solvents . International Journal of Technology. Volume 10(6), pp. 1251-1259
A Arifutzzaman Investigation of Extraction Yields of Exfoliated Graphene in Deionized Water from Organic Solvents
A. F. Ismail Department of Mechanical Engineering, Faculty of Engineering, International Islamic University Malaysia, Malaysia
M. Zahangir Alam Department of Biotechnology Engineering, Faculty of Engineering, International Islamic University Malaysia, Malaysia
Ahsan Ali Khan Department of Manufacturing and Materials Engineering, Faculty of Engineering, International Islamic University Malaysia
Saidur Rahman Department of Engineering, Lancaster University, Lancaster, LA1 4YW, UK
Email to Corresponding Author


Organic solvent is suitable for the exfoliation of graphene. However, for the end application of exfoliated graphene it needs to extract and re-disperse to the required media. Extraction of exfoliated graphene from organic solvents to a polar solvent is a crucial challenge in graphene synthesis. The principal objective of this study is to examine the concentration yields of exfoliated graphene extraction and make a comparison of the estimated percentage concentrations of graphene in between organic solvents and deionized water (DW). Exfoliated graphene from the solvents N-Methyl-2-Pyrrolidone (NMP) and N, N-dimethylformamide (DMF) were taken. The extraction of exfoliated graphene was conducted by membrane filter using a vacuum filtration system. Concentration of exfoliated graphene solvents were estimated using Beer’s law by preparing separate standard graphs. It is seen that concentrations of exfoliated graphene in DW from both NMP and DMF solvents for all the centrifugation was reduced. These reductions were found to be varied from ~ 21 to 25.5%. Morphology analysis using TEM and FESEM images reveals that the few layers of graphene staked in the sonication assisted liquid phase exfoliated (LPE) graphene in both of NMP and DMF solvents. Very minor levels of aggregation occurred and very slight sedimentation appeared after centrifugation of 30 days.

Concentration; Extraction; Graphene; Re-dispersion; Solvents


A one atom thick graphene sheet of ultra-thin carbon film with two-dimensional planer’s geometry was first discovered by Novoselov et al. (2004). Various chemicals and natural resources (Supriadi et al., 2017) have been used as precursor materials for the fabrication of graphene. This carbon based material has a vast application in nanofluids (Ahlatli et al., 2016). Various types of graphene have been processed using various methods, such as chemical vapor growth (Hu et al., 2012), molecular building blocks by annealing of SiC substrates (Palma & Samorì, 2011), bottom-up growth through the wet ball-milling method (Leon et al., 2011), and burning Mg metal in solid CO2 (dry ice) (Arifutzzaman et al., 2015). Due to their initial setup and very low final yielding limits, their wide implication of graphene fabrication (Ciesielski & Samorì, 2014), in this case green chemistry, could be a viable approach (Kusrini et al., 2015).

Commercially obtainable microcrystalline graphite flakes can be exfoliated into distinct graphene flakes by an interaction in a solvent (Kotov et al., 1996). To exfoliate the graphite flakes into separate layers, two different mechanical forces are required (Arao et al., 2016). One is normal force which changes the interlayer space, and the other is the lateral shared force which slides away from the sheets. Applying the shear force across the flake’s of graphite surfaces causes the exfoliation graphite into the separate graphene layers (Yang & Liu, 2014). This chemical or liquid exfoliation method possesses very modest and straight forward one-step processes to exfoliate graphene in the liquid solvents which is most widely used technique to produce graphene (O’Neill et al., 2011; Khan et al., 2012). The surface energy of the organic solvents NMP (40 m Jm-2) or DMF (37 m Jm-2) (Hernandez et al., 2008) perfectly matches the graphite (Zacharia et al., 2004) and fulfils the requirement for a successful exfoliation to graphene sheets (Compton et al., 2010). Sedimentation based centrifugation is used to separate the graphene (O’Neill et al., 2011). In this approach, a higher centrifugation rate (rpm) gives lower concentrations of the graphene (Khan et al., 2012).

An organic solvent is necessary for the exfoliation of graphite to get separate graphene sheets. However, for further application purposes, it may need to extract the graphene from the solvent produced and re-dispersed in to a required solvent. For example, organic solvents will be influenced highly on the thermal and electrical transport properties (Behabtu et al., 2010). Sometimes, it could have a high impact on the device performance. However, solvents with low boiling points, such as water, will be preferable because they are incompatible for exfoliation and very suitable for the end application, such as the preparation of the heat transfer of nanofluids (Ciesielski & Samorì, 2014).

Irin et al. (2015) analyzed the different techniques for removing solvents from graphene dispersion. They found that vacuum filtration was the most suitable way compared to the other techniques, such as dialysis and spray drying, to separate the graphene from the organic solvent dispersion, and re-disperse to other suitable media. After vacuum filtration, graphene flakes prevail with an ordered multi-layered film on the filter paper (Dikin et al., 2007). Due to the application of constant suction force by a vacuum pump to the graphene sheets at the interface of solid and liquid, sheets are placed parallel to the membrane filter (Yang et al., 2011). Repulsive force amongst the solvent and exfoliated graphene was sufficient in preventing the graphene sheets from the re-staking together before they touch the filters surface (Yang et al., 2011). For these reasons, most of the graphene sheets tend to prevail horizontally on the membrane filter surface during the suction by vacuum pump (Cheng & Li, 2013). Importantly, it was confirmed by Yang et al. (2011) that the chemically transformed graphene sheets never return to their graphite form farther in the created wet film on the membrane filter. Although, literature has found few reports on the analysis of graphene yields in different base liquids, and based on knowledge, there is no systematic investigation reporting on the analysis of extraction yields of exfoliated graphene from the exfoliating organic solvents into DW. Therefore, the objective of this research is to conduct a systematic investigation on the extracted exfoliate graphene concentration yields, and make a comparison among the percentage variation of concentration yields into two different organic solvents with DW.


Exfoliated graphene was effectively extracted from two different organic solvents, NMP and DMF, and re-dispersed into DW using a vacuum filtration process. From the investigation, it can be seen that concentrations of exfoliated graphene in DW from both solvents for all the centrifugation was found to be reduced. These reductions were found to be varied from ~21 to 25.5%. Morphology analysis using TEM and FESEM images reveals that, the few layers of graphene in the exfoliated graphene in both of solvents. Very minor levels of aggregation occurred and very slight sedimentation appeared after centrifugation of 30 days.


The authors acknowledge the lab facilities under the Manufacturing and materials Engineering Department in the International Islamic University Malaysia for conducting experiments reported in this work.

Supplementary Material
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