3 Bio-nanotechnology Application in Wastewater Treatment
39
therapeutic utilizations. It has a surface Plasmon resonance and an extensive crossscattering section, making it ideal for use in molecular adhesives. Biosynthesis of
inorganic materials has been reported by many researchers, and it is recognized that
these methods are considered clean, inexpensive, and non-toxic to humans and the
environment. Interest in research and development has grown around silver nanoparticles due to its unique properties that can be applied to bio-nanotechnology (Fayaz
et al. 2011).
3.3 Synthesis Methods of Metallic Nanoparticles
There are two techniques used in the process of synthesizing nanoparticles, bottomup and top-down (Biswas et al. 2012). A bottom-up approach is a self-generated
nanomaterial engineering process where atoms, molecules, or clusters assemble to
form small-scale materials on a nanometer. The atoms and molecules are automatically generated in a process called self-assembly under certain conditions, but this
approach can consume much time. While in the Top-down approach, the process
begins with the use of bulk materials in multiple ways to obtain the smaller sizes
commonly used in the manufacture of microprocessors. In recent years, there has
been an increase in interest in the production of metallic nanoparticles, because of its
unique properties. In many applications, metallic nanoparticles are different metals,
each with a distinct function. There are several studies aimed at producing metallic
nanoparticles, and the most common methods of producing metallic nanoparticles
are the physical and chemical methods.
The physical method uses different processes for the synthesis of metal nanoparticles such as laser ablation, laser evaporation and radiofrequency plasma (Owens
and Poole 2008), epitaxy of sub-atomic shaft (Atkinson et al. 2006), and deposition
of Physical vapour. In Radio Frequency plasma technique, high voltage is being
utilized to produce nanoparticles (Gunnarsson 2018). The method of evaporationintensification includes the use of an oven at atmospheric pressure, where the required
materials are stored inside the boat located in the centre of the oven and evaporated in
the gas carrier (Kruis et al. 2000). The method of laser evaporation is where the highdensity package is placed on the surface of a metal plate to evaporate the atoms of
the metal and then cooled to obtain the nanoparticles using helium gas in the vacuum
(Turkki 1999). Physical methods have some major drawbacks such as great energy
consumption and take period to obtain thermic constancy (El-Nour et al. 2010).
Chemical methods are widely utilized methods for producing nanoparticles, for
example sol-gel and hydrolysis (Danks et al. 2016) and chemical vapour deposition
(Palgrave and Parkin 2008). Chemical vapour precipitation includes deposition on an
interaction material using vapour of phase precursors as chemical reaction (Khanna
2016). Chemical vapour precipitation has a disadvantage of gases of precursor been
liable to fire danger and corrosion (Lukaszkowicz and Dobrza´ nski 2008).
Given restriction of chemical and physical processes, researchers have paid keen
attention to improve a secure, eco-friendly, and inexpensive alternate process for
39
therapeutic utilizations. It has a surface Plasmon resonance and an extensive crossscattering section, making it ideal for use in molecular adhesives. Biosynthesis of
inorganic materials has been reported by many researchers, and it is recognized that
these methods are considered clean, inexpensive, and non-toxic to humans and the
environment. Interest in research and development has grown around silver nanoparticles due to its unique properties that can be applied to bio-nanotechnology (Fayaz
et al. 2011).
3.3 Synthesis Methods of Metallic Nanoparticles
There are two techniques used in the process of synthesizing nanoparticles, bottomup and top-down (Biswas et al. 2012). A bottom-up approach is a self-generated
nanomaterial engineering process where atoms, molecules, or clusters assemble to
form small-scale materials on a nanometer. The atoms and molecules are automatically generated in a process called self-assembly under certain conditions, but this
approach can consume much time. While in the Top-down approach, the process
begins with the use of bulk materials in multiple ways to obtain the smaller sizes
commonly used in the manufacture of microprocessors. In recent years, there has
been an increase in interest in the production of metallic nanoparticles, because of its
unique properties. In many applications, metallic nanoparticles are different metals,
each with a distinct function. There are several studies aimed at producing metallic
nanoparticles, and the most common methods of producing metallic nanoparticles
are the physical and chemical methods.
The physical method uses different processes for the synthesis of metal nanoparticles such as laser ablation, laser evaporation and radiofrequency plasma (Owens
and Poole 2008), epitaxy of sub-atomic shaft (Atkinson et al. 2006), and deposition
of Physical vapour. In Radio Frequency plasma technique, high voltage is being
utilized to produce nanoparticles (Gunnarsson 2018). The method of evaporationintensification includes the use of an oven at atmospheric pressure, where the required
materials are stored inside the boat located in the centre of the oven and evaporated in
the gas carrier (Kruis et al. 2000). The method of laser evaporation is where the highdensity package is placed on the surface of a metal plate to evaporate the atoms of
the metal and then cooled to obtain the nanoparticles using helium gas in the vacuum
(Turkki 1999). Physical methods have some major drawbacks such as great energy
consumption and take period to obtain thermic constancy (El-Nour et al. 2010).
Chemical methods are widely utilized methods for producing nanoparticles, for
example sol-gel and hydrolysis (Danks et al. 2016) and chemical vapour deposition
(Palgrave and Parkin 2008). Chemical vapour precipitation includes deposition on an
interaction material using vapour of phase precursors as chemical reaction (Khanna
2016). Chemical vapour precipitation has a disadvantage of gases of precursor been
liable to fire danger and corrosion (Lukaszkowicz and Dobrza´ nski 2008).
Given restriction of chemical and physical processes, researchers have paid keen
attention to improve a secure, eco-friendly, and inexpensive alternate process for