International Journal of Membrane Science and Technology, 2022, 9, 1-12 1
E-ISSN: 2410-1869/22 © 2022 Cosmos Scholars Publishing House
Synthesis and Characterization of Reduced Graphene Oxide from
Indigenous Coal: A Non-Burning Solution
Saud Hashmi
1
, Asim Mushtaq
1,*
, Rafiq Ahmed
1
and Zaeem Uddin Ali
2
1
Polymer and Petrochemical Engineering Department,
2
Chemical Engineering Department, NED University of
Engineering & Technology, Karachi, Sindh, Pakistan
Abstract: A great deal of research has been made into producing graphene or graphene oxide by utilizing graphite as a
starting material. An alternate method of producing graphene is using low-grade coal as a starting material. Due to the
abundance of coal in Pakistan and increased environmental concern from Government bodies and environmental
agencies alike, increased awareness is being made to move over to non-burning solutions to fossil fuels. Experiments
were performed on two ranks of coal in parallel; lignite and sub-bituminous. Coal was pretreated first to remove the
undesired impurities, which could hinder the graphene synthesis later on. Acid washing with multiple waters was done,
followed by carbonization in the furnace. After the pretreatment, the Hummers method was chosen as a chemical
process for synthesizing graphene. It is a less complex method, can be easily performed with available resources, and is
comparatively cheaper and environmentally friendly. The resulting sample was tested with SEM and EDS, and graphene
oxide was confirmed. It was followed by a water-based reduction method to produce reduced graphene oxide from
graphene oxide. This modified hydrothermal method was chosen for its eco-friendliness. The final sample was dried and
tested with XRD, SEM, FTIR, and RAMAN to authenticate the type of graphene produced. Graphene has remarkable
properties, including very high tensile modulus, extremely high thermal conductivity, and charge carrier mobility
exceeding 200,000 cm
2
V
-1
s
-1
. Such properties are reason enough to explore low cost, environment friendly, and scalable
means of graphene production. Potential graphene applications in various medical, chemical and industrial processes
are enhanced or enabled by using new graphene materials.
Keywords: Coal, Graphene graphite, Hummers method, Hydrothermal method, Water-based reduction method.
INTRODUCTION
Since graphene’s discovery in 2004, graphene has
been of great attraction to the scientific community.
Graphene catches scientific attention due to its
fascinating electronic, thermal, mechanical, catalytic,
optical, and magnetic properties with great potential in
various applications ranging from energy storage,
nanocomposite to biomedical materials. It has led to
significant interest in the large-scale production of
graphene. Many methods have been proposed,
including electrochemical exfoliation, graphite
exfoliation via intercalates, graphite solvation, arc
discharge, unzipping carbon nanotubes, epitaxial
growth, chemical vapor deposition, as well as other
techniques of chemical oxidation based on the
Hummers method [1, 2]. Most of these methods utilize
graphite as a starting material because it’s rich in
carbon content and high purity make it most suitable for
graphene synthesis. Undoubtedly, high-quality
graphene can be obtained from a graphitic base,
making it expensive. There is a need for alternate base
material for graphene synthesis, which is relatively
cheap and readily available in nature [3, 4].
*
Address correspondence to this author at the Department of Polymer and
Petrochemical Engineering, NED University of Engineering & Technology,
Karachi, Sindh, Pakistan. Tel: +92-99261261 Ext: 2419;
E-mail: engrasimmushtaq@yahoo.com
Coal is the oldest carbon source known to
humankind, extensively used as a solid fuel worldwide,
and has the most significant global fossil fuel reserves.
The burning of coal is malignant to the environment
and the living things, but because coal is so copious
and inexpensive, many people are reluctant to give it
up as a fuel source. One of the significant downsides of
burning coal is that it releases toxins. Coal contains
sulfur and other elements, including dangerous metals
such as mercury, lead, and arsenic that escape into the
environment when it is burned. Burning coal unleashes
substantial amounts of carbon dioxide and oxides of
sulfur into the atmosphere. These emissions have been
shown to increase the greenhouse effect in the
atmosphere and global. The reality is that coal is not
going away, nor is the growth that spurs its
consumption. The challenge is how to utilize coal
without these disastrous emissions. Due to the
abundance of coal in Pakistan and increased
environmental concern from Government bodies and
environmental agencies alike, increased awareness is
being made to move over to non-burning solutions to
fossil fuels [5-7].
The high carbon content and solubilization of
minerals in coal can potentially utilize the inherently
dirty solid fuel to a source of prestigious carbon
nanomaterials such as graphene, graphene quantum
dots, or carbon nanotubes. The coal is constituted of