International Journal of Engineering Trends and Technology (IJETT) – Volume 26 Number 5- August 2015
Biosynthesis and measurement of thermal conductivity of ZnO
material
B. Gopal Krishna*1, M. Jagannadha Rao2,
1
HLDEPP Laboratory, School of Studies in Physics and Astrophysics, Pt.
Ravishankar Shukla University, Raipur 492008, India.
2
Department of Geology, Andhra University, Visakhapatnam 530003, India.
Abstract - Microbes like bacteria, algae, fungi and
virus play an important role to catalyst chemical
reactions. In Nature, ores or minerals of different
compounds are formed due to microbial environment
and other factors like weathering. Microbial
environment is also instrumental in forming calcium
containing silicate minerals. Chemical reactions occur
under microbial environment because microbes have the
ability to control or modify different factors like pH,
chemical potential and temperature during reactions. In
this paper, synthesis of zinc oxide using zinc in presence
of atmospheric oxygen under microbial environment in
a laboratory is being adopted to produce the required
material. XRD technique is used to confirm the
formation of zinc oxide (ZnO).Thermal conductivity of
zinc oxide material is studied using composite wall
apparatus.
Keywords - Zinc, ZnO composite, thermal conductivity,
microbes, atmospheric O2, XRD.
I.
Three major forms of transformations have been
observed in the cycling of elements in nature:
Introduction
Zinc oxide, with its unique physical and chemical
properties, such as high chemical stability, high
electrochemical coupling coefficient, broad range of
radiation absorption and high photostability, is a
multifunctional material [1,2]. In materials science, zinc
oxide is classified as a semiconductor in group II-VI,
whose covalence is on the boundary between ionic and
covalent semiconductors. A broad energy band (3.37
eV), high bond energy (60 meV) and high thermal and
mechanical stability at room temperature make it
attractive for potential use in electronics, optoelectronics
and laser technology [3,4]. The piezo and pyroelectric
properties of ZnO mean that it can be used as a sensor,
converter, energy generator and photocatalyst in
hydrogen production [5,6]. Because of its hardness,
rigidity and piezoelectric constant it is an important
material in the ceramics industry, while its low toxicity,
biocompatibility and biodegradability make it a material
of interest for biomedicine and in pro-ecological
systems [7–9].
Microbial environment induce certain chemical
reactions in the formation of metal oxide materials. The
ISSN: 2231-5381
synthesis of ZnO material is induced using microbial
environment under laboratory conditions in our
research. The microbes such as Stenotrophomonas
maltophilia, Pseudomonas putida, Pseudomonas
aeroginosa, Enterobacter cloacae, Staphylococcus sciuri,
Acinectobacter cacloaceticus, Pantoeau agglomerans,
and Flavobacterium spp. have been used in the chemical
process to synthesize ZnO material. All these microbes
were concentrated together in the experimental container
at the same time during the synthesis of the material.
The biotechnology utilizes microbial environment to
produce required chemical reactions. Chemical reactions
take place as a result of interaction of physical, chemical
and biological components with each other. These
interactions play an important role for the molecule or
an element to modify its physicochemical form. This
process is called transformation. However, the change is
not one way, environment also plays vital role in the
modification of temperature/ chemical reaction
(pH)/conductivity etc.
1. Physical transformations which include fixation,
dissolution, precipitation and volatilization.
2. Chemical transformations which include precipitation
and solubilization of minerals and other
molecules.
3. Biochemical transformations in which the physical
and chemical changes are brought about by the living
microbial processes. For example, the microbial process
is involved in fixation and transformations during
biosynthesis or biodegradation.
Besides these, certain other processes such as „Spatial
translocations‟ of materials (from water column to
sediments or from soil to atmosphere) and changes in
the physical environment such as pressure due to piling
may also be involved [10-21].
In this paper, the synthesis of ZnO material has been
carried out by using Zinc and atmospheric oxygen under
microbial environment. As stated above, we can surmise
that microbes such as bacteria, virus, algae and fungi
etc. are capable of transformations or perform chemical
reactions.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 26 Number 5- August 2015
II. Objectives
1.
2.
Biosynthesis of ZnO material has been carried
out by using Zinc in presence of atmospheric
O2 in the laboratory utilizing microbial
environment.
Measurement of thermal conductivity of ZnO
material.
III. Experiment
In our research, ZnO is synthesized in the laboratory.
To synthesize the required material, zinc plate was taken
in a cylindrical container made up of non magnetic
material. The atmospheric O2 plays an important role in
this
experiment.
The
microbes
such
as
Stenotrophomonas maltophilia, Pseudomonas putida,
Pseudomonas aeroginosa, Enterobacter cloacae,
Staphylococcus sciuri, Acinectobacter cacloaceticus,
Pantoeau agglomerans, and Flavobacterium spp. were
concentrated together around the Zn plate in the
presence of atmospheric oxygen inside the container.
The experimental container which contained the zinc
plate and microbes was kept under low magnetic field of
around 10-2 Tesla. Under magnetic field, it was observed
in some research paper that microbes move along a
specific direction and they show some unique
characteristics [22, 23]. The experiment was carried out
for 12 hours at room temperature 27◦C. After 12 hours
the sample was taken out from the experimental
container. Then XRD was carried out on the prepared
sample which confirmed the formation of ZnO material .
The microbial system concentrated around the zinc plate
played an important role to combine the molecules of Zn
and atmospheric oxygen to form ZnO material. These
microbes controlled the temperature, pH value, chemical
potential of the reaction and various other parameters
like physical environment to carry out chemical reaction
[24,25]. The systematic arrangement of the experiment
is shown in the fig. 1.
The reaction between Zinc and atmospheric O2
involved the following steps in microbial environment
Zn O2
2ZnO
(1)
IV. XRD analysis
The x-ray diffraction analysis was carried out on xray diffractrometer. The synthesized ZnO composite
sample, which was analyzed on XRD, consisted of x-ray
tube with Cu k-Alpha. The chart depicted had peaks
which ran from 5˚ to 90˚ for Zn and synthesized ZnO
material consuming current of 30mA and voltage of 40
kV at temperature 25˚C. The XRD chart was given
numbers coinciding the numbering of the sample peaks.
V. Thermal conductivity of ZnO material
For one-dimensional and rectilinear heat flow, the
steady-state heat transfer in polymeric materials can be
described by the Fourier‟s law of heat conduction:
q
k
dT
dx
(2)
where q is the heat flux (i.e., the heat transfer rate per
unit area normal to the direction of flow), x is the
thickness of the material,
dT
is the temperature
dx
gradient per unit length, and the proportionality constant
k is known as the thermal conductivity. The units for
thermal conductivity
k are expressed as W cmK in
SI units.
The thickness of the zinc oxide material is 0.3 cm
with area 19 cm2. The temperature difference dT is
3K . The heat measured by the help of composite wall
apparatus is 333 watt.
From equation 2, the thermal conductivity k of the
synthesized bulk zinc oxide material was found out to be
1.75 W cmK .
VI. Results
Fig. 1 Experimental arrangement for ZnO synthesis
ISSN: 2231-5381
The synthesis of ZnO composite material using Zn,
atmospheric oxygen and microbes was carried out
successfully under laboratory conditions at room
temperature 27˚C. The formation of ZnO material was
confirmed by XRD analysis. The XRD pattern of Zn and
ZnO are shown in fig. 2 and fig. 3.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 26 Number 5- August 2015
microbes have the ability to control or change chemical
potential, free energy, pH value, temperature, oxidationreduction process and physical environment like
pressure required for proper chemical reaction between
two or more molecules [24,25].
This experimental result concludes that microbes have
the ability to carry out chemical reaction between zinc
and O2 to transform them into ZnO material in
laboratory conditions. Thermal conductivity of the
synthesized material was 1.7 W cmK which is nearly equal
Fig. 2 XRD Pattern of Zn
to the thermal conductivity of bulk ZnO material[29].
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VII. Conclusions
Microbes carry out oxidation-reduction reactions in
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