Open Access Review Article
Arora et al., J Pet Environ Biotechnol 2014, 5:2
DOI: 10.4172/2157-7463.1000170
Volume 5 • Issue 2 • 1000170
J Pet Environ Biotechnol
ISSN: 2157-7463 JPEB, an open access journal
Abstract
The increasing demand of fossil fuels resources and their continuous consumption has created a necessity for
exploring the alternative resources of energy like gas hydrates. Gas hydrates exist under oceans and in permafrost
regions. They are also known as methane hydrates or methane clathrates. These are stable at high pressure and
low temperature. These are formed when methane gas comes in contact with sediments saturated with water.
Pseudomonas aeruginosa and Bacillus subtilis were found in gas hydrates samples investigations from Gulf of
Mexico and these microbes generated biosurfactants like Rhamnolipid and Surfactin. The current paper reports the
effects of biosurfactants such as Rhamnolipid, Surfactin, Snomax, Emulsan, Phospholipids, Hydroxystearic acid etc.
on Gas Hydrate formation.
Effects of Biosurfactants on Gas Hydrates
Amit Arora
1
, Swaranjit Singh Cameotra
2
*, Rajnish Kumar
3
, Pushpendra Kumar
4
, Chandrajit Balomajumder
1
1
Department of Chemical Engineering, Indian Institute of Technology, Roorkee, India
2
Institute of Microbial Technology, Chandigarh, India
3
Chemical Engineering and Process Development Division, National Chemical Laboratory, Pune, India
4
Keshav Dev Malviya Institute of Petroleum Exploration, Oil and Natural Gas Corporation (ONGC), Dehradun, India
Keywords: Gas hydrates; Rhamnolipid; Surfactin; Snomax; Emulsan;
Hydroxystearic acid; Phospholipid
Introduction
Gas hydrates belong to a class of inclusion compounds and are
known as clathrates. In these class of compounds host molecules like
water encapsulates the guest molecules like methane, ethane, propane,
CO
2
etc. and forms a molecular cage. In these types of compounds
only intermingling of molecules takes place and there is no chemical
reaction occurs as such. Water molecules form hydrogen bonding and
forms a polyhedral cavity and the guest molecules occupies the void.
Te CO
2
sequestration can help in releasing the methane captured
in gas hydrates below the sea foors. Te amount of energy released
when CO
2
gas hydrates gets formed is more than the amount of energy
required to dissociate methane gas hydrates, So, CO
2
sequestration in
gas hydrates can achieve two objectives at one time i.e. it can reduce the
global warming and give the energy [1].
Te gas hydrate reserves around the globe have organic carbon
contained in them almost double than the amount contained in all
fossil fuels on Earth as shown in Figure 1.
Molecular Structure
Te common structure formed by gas hydrates is structure I which
is formed by gases like methane and molecules like propane, natural gas
form structure II.
Te Structure I consist of 2 small cages made up by 12 pentagonal
surfaces called “5
12
” and 6 larger cages of again 12 pentagonal and two
hexagonal surfaces called 5
12
6
2
[3].
Te unit cell consists of water molecules = (12x5
12
+2x5
12
6
2
= 46)
[4].
Structure II consist of 16 small cages made up by 12 pentagonal
surfaces called “5
12
” and 8 larger cages of again 12 pentagonal and four
hexagonal surfaces called 5
12
6
4
[3].
Te unit cell consists of water molecules = (16x5
12
+8x5
12
6
4
= 136)
[4].
Te hydrate cavities of structure I and structure II as shown in
Figure 2.
For methane hydrate in structure I complete flling of both the
large (5
12
6
2
) and small (5
12
) cavities by methane molecules will give
hydrate i.e. CH
4
•5.75H
2
O. However complete flling of occupancy is not
possible which leads to a hydrate ratio of around 1:6 (i.e. CH
4
•6H
2
O),
which is equivalent to 96% cage occupancy [5,6], based on this 1 m
3
of
methane gas hydrate can occupy 167 m
3
of methane at STP.
Physical Properties of Gas Hydrates
Gas Hydrates are non-stoichiometric compounds Gas Hydrates
*Corresponding author: Swaranjit Singh Cameotra, Senior Principal
Scientist, Institute of Microbial Technology, Sector 39A, Chandigarh
-160036, India, Tel: +91-9041036750; E-mail: ssc@imtech.res.in
Received March 14, 2014; Accepted April 17, 2014; Published April 25, 2014
Citation: Arora A, Cameotra SS, Kumar R, Kumar P, Balomajumder C (2014)
Effects of Biosurfactants on Gas Hydrates. J Pet Environ Biotechnol 5: 170.
doi:10.4172/2157-7463.1000170
Copyright: © 2014 Arora A, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited.
Soil
7.45%
Dissolved
OM in
water
5.21%
Land biota
4.41%
Peat
2.66%
Others
0.37 %
Fossil Fuels
26.62%
Gas
Hydrates
53.24%
Figure 1: Distribution of organic carbon on Earth (Total 18,777 Gt) [2], Gt =
Giga tonne.
Journal of Petroleum &
Environmental Biotechnology
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ISSN: 2157-7463