3 Bio-nanotechnology Application in Wastewater Treatment
35
devices that are required in the area of medicine and vision service. Furthermore,
nanotechnology applications have gained widespread acceptance in the fields of
medicine, energy, biotechnology, agriculture, and environment (Saranyaadevi et al.
2014).
Development of nanomaterials researches focuses on the synthesis, modification,
and characterization of nanomaterials (Wang 2000). Nanomaterials can be divided
into two main types; the first type is all three dimensions within a nanometre range (1–
100 nm) called nanoparticle, maybe polymer, metallic, or metal oxide (Rotello 2004;
Gubin 2009). The second type has at least one dimension within the nanoscale range
and is called nanostructure (Han et al. 2012). They can be one external dimension
(1D) that is out of 100 nm range, such as nanorods and nanowires or two external
dimensions (2D) like Nano sheets and Nano films (Cao 2004).
Synthesizing of nanomaterials is divided into two approaches, the “top-down” and
the “bottom-up” approach. Top-down, where the size of the material is reduced to
obtain smaller materials started from bulk materials and processed through physical
and chemical methods. The synthesis from bottom-up is called self-assembly, where
materials are formed by assembling atoms or by clustering molecules to obtain bigger
nanomaterials. Nanoparticles have been prepared in the past years, using physical and
chemical methods such as thermal decomposition, laser evaporation, chemical and
physical vapour deposition (Iravani et al. 2014). The hazardous reagents, maximum
requirements are often involved in chemical and physical methods. High-density
lasers are used to evaporate the atoms and then cool them to form nanoparticles;
high-temperature helium gas and radiofrequency plasma are also used to produce
nanoparticles. The silver nanoparticles were prepared using the chemical method,
where silver salt was used as precursor and sodium borohydride as a reducing agent,
colloidal solution as a stabilizing agent (De Sio et al. 2015).
Recently, nanoparticles are produced by chemical and physical methods. These
methods produce nanoparticles in large quantities in a short time, but these methods
require high voltage, high temperatures, and use of non-degradable materials (Kruis
et al. 2000). The above methods are costly, require high energy, and produce a
toxic waste that can harm the environment in general and humans in particular.
The use of these products may be limited to different applications (Mahdieh and
Fattahi 2015). Today, there is a new approach that uses biological sources instead
of chemical and physical methods in producing nanoparticles, where the production
process is used from (bottom-up), and this is a new field that contributes to the
development of nanoscience and is called bio-nanotechnology (Singh et al. 2016;
Yashni et al. 2019b). Biotechnologies have become more attractive because they are
environmentally friendly, do not consume too much energy, and have high efficiency
in producing nanoparticles with unique properties (Kulkarni and Muddapur 2014).
Also, biogenic sources of plants (Njagi et al. 2010) and microorganisms (Hulkoti
and Taranath 2014) have shown their potential extensively in the green synthesis
of nanomaterials and have many applications. Plants possess different leaves that
are widespread on the ground. This includes large and small sizes and different
colours, some are considered as food for many organisms, while others are used in
the treatment of some diseases.
35
devices that are required in the area of medicine and vision service. Furthermore,
nanotechnology applications have gained widespread acceptance in the fields of
medicine, energy, biotechnology, agriculture, and environment (Saranyaadevi et al.
2014).
Development of nanomaterials researches focuses on the synthesis, modification,
and characterization of nanomaterials (Wang 2000). Nanomaterials can be divided
into two main types; the first type is all three dimensions within a nanometre range (1–
100 nm) called nanoparticle, maybe polymer, metallic, or metal oxide (Rotello 2004;
Gubin 2009). The second type has at least one dimension within the nanoscale range
and is called nanostructure (Han et al. 2012). They can be one external dimension
(1D) that is out of 100 nm range, such as nanorods and nanowires or two external
dimensions (2D) like Nano sheets and Nano films (Cao 2004).
Synthesizing of nanomaterials is divided into two approaches, the “top-down” and
the “bottom-up” approach. Top-down, where the size of the material is reduced to
obtain smaller materials started from bulk materials and processed through physical
and chemical methods. The synthesis from bottom-up is called self-assembly, where
materials are formed by assembling atoms or by clustering molecules to obtain bigger
nanomaterials. Nanoparticles have been prepared in the past years, using physical and
chemical methods such as thermal decomposition, laser evaporation, chemical and
physical vapour deposition (Iravani et al. 2014). The hazardous reagents, maximum
requirements are often involved in chemical and physical methods. High-density
lasers are used to evaporate the atoms and then cool them to form nanoparticles;
high-temperature helium gas and radiofrequency plasma are also used to produce
nanoparticles. The silver nanoparticles were prepared using the chemical method,
where silver salt was used as precursor and sodium borohydride as a reducing agent,
colloidal solution as a stabilizing agent (De Sio et al. 2015).
Recently, nanoparticles are produced by chemical and physical methods. These
methods produce nanoparticles in large quantities in a short time, but these methods
require high voltage, high temperatures, and use of non-degradable materials (Kruis
et al. 2000). The above methods are costly, require high energy, and produce a
toxic waste that can harm the environment in general and humans in particular.
The use of these products may be limited to different applications (Mahdieh and
Fattahi 2015). Today, there is a new approach that uses biological sources instead
of chemical and physical methods in producing nanoparticles, where the production
process is used from (bottom-up), and this is a new field that contributes to the
development of nanoscience and is called bio-nanotechnology (Singh et al. 2016;
Yashni et al. 2019b). Biotechnologies have become more attractive because they are
environmentally friendly, do not consume too much energy, and have high efficiency
in producing nanoparticles with unique properties (Kulkarni and Muddapur 2014).
Also, biogenic sources of plants (Njagi et al. 2010) and microorganisms (Hulkoti
and Taranath 2014) have shown their potential extensively in the green synthesis
of nanomaterials and have many applications. Plants possess different leaves that
are widespread on the ground. This includes large and small sizes and different
colours, some are considered as food for many organisms, while others are used in
the treatment of some diseases.