**5.1 Nanofibers application as catalysis**

Highly porous and large surface area bearing electrospun nanofibers prominently used as solid supports in catalysts. Nanofibers of some materials having excellent semiconducting property make them suitable in photo-catalysts for removing

**29**

*Green Synthesis of Nanofiber and Its Affecting Parameters*

**5.2 Nanofibers application in energy technology**

lignin nanofiber network showed has surface area of 1670m<sup>2</sup>

specific electrical double layer capacitance at low cost [68].

**5.3 Nanofibers application in environmental science**

*5.3.1 Nanofiber-based membrane for filtration*

lent specific gravimetric capacitance of ~240 F per gram that was better than many nanostructured carbon or metal oxides [67]. The carbon based nanofibers have high

Electrospun ceramic nanofibers membranes are able to remove suspended particulate matter from air and other impurities dissolved in water. The highly

per gram and excel-

organic molecules from air flow or aqueous solution. The extent of catalysis and its efficiency is governed by surface area of the catalyst. Ceramic nanofibers possess extraordinarily high specific surface area are nice materials for their application as catalyst for chemical reaction. The ceramic nanofibers mats of Titanium dioxide (TiO2), zirconium dioxide (ZrO2) and tin dioxide (SnO2) have been employed as support material for loading noble metal nanostructures catalysis in different applications [60]. The membranous catalytic system have distinctive benefit over other process in terms of its operation in a continuous flow mode, relatively short reaction time and even more importantly it need not separation of product after completion of reaction. In addition to large surface area, the support material should also be stable and good conductor of electron. The nanoparticles catalyst of noble-metal Pt, Pd, Rh etc. are homogeneous spread on solid support of carbon black for maximizing possible surface site availability [61]. The Pd-coated Titanium dioxide (TiO2) nanofibers performed well in cross-coupling reaction [62]. It is interesting that the ceramic nanofiber substrate can pointedly influence noble-metal catalyst deposition [63].

Energy shortage is one of the most serious issues of the 21st century because of limited natural energy resources like crude oil, natural gas, coal and uranium that are fulfilling the energy need for everyday life at presented. For rapid economic growth, will require subsequent increase in energy demand mean but the rate of oil production will no longer be adequate. This is evident from the rising price of crude oil. Presently, large volumes of carbon dioxide emitted by industrial burning of fossil fuels are deteriorating climate of the globe. So, it is necessity of the time to identify alternate environmentally friendly new sources of energy that are able to replace current energy supply. The people are trying to converse energy from renewable sources such as the sun, wind, and tides. The most promising energy conversion/storage devices likely to fulfill the need are based on photovoltaic cells, lithium batteries, and fuel cells. For example, Mai and colleagues demonstrated high performance lithium ion battery electrode based on electrospun vanadium oxide nanofibers [64]. They were able to prepare ultra-long hierarchical vanadium oxide nanowires of fine diameter (100–200 nm) and several millimeters using the low-cost starting materials by ES combined with annealing. The 1D characteristic of electrospun ceramic nanofibers have been widely explored as a new class of promising building blocks for fabricating the devices. Energy storage devices are becoming a very common in everyday life of public due to exponential expansion of digitization. Many devices need stored energy for their functions are electronic mobile, autonomous sensors and various kind of vehicle. So, the reliable energy storage devices with high power density and structural integrity are in demand for their use in various devices [65, 66]. Green flexible network of carbon nanofiber can be deriving from abundantly available but underutilized bioresources lignin. The PVA

*DOI: http://dx.doi.org/10.5772/intechopen.94539*

**Figure 4.** *Basic applications of nanofibers.*

*Green Synthesis of Nanofiber and Its Affecting Parameters DOI: http://dx.doi.org/10.5772/intechopen.94539*

*Nanofibers - Synthesis, Properties and Applications*

feature are schematically represented in **Figure 3**.

**4.4 Calcinations of green nanofibers**

crystallization of Cu-Ce oxide.

**5. Potential utilizations of nanofibers**

**5.1 Nanofibers application as catalysis**

below. The basic nanofiber application shown in **Figure 4**.

environmental condition fluid jet ejected continuously from the nozzle and accelerated jet moved towards the collector plate. During this movement of jet the solvent get evaporated leaving ultra thin fibers on the collector plate. The ES process continued until all the solution in the syringe was exhausted. The complete sequence of spinning solution preparation and nanofiber synthesis, its calcination and final morphological

To complete the formation of CuO/CeO2 nanofibers, the composite fibers prepared as above were left exposed to ambient moisture for 5 hr. to allow complete hydrolysis, then electrospun polyvinyl pyrrolidone (PVP) /cerium nitrate hexahydrate (CN)/copper acetate monohydrate (CA) fiber mats were removed from the aluminum foil. These composite fibers were placed on a ceramic crucible able to withstand high temperature and consequently calcined (500°C, 3 hr) in a muffle furnace in presence of air for eliminating the organic constituents and activating

Now a days, scientists and researchers have shown strong interest to develop the electrospun ceramic nanofibers in different field. The most significant characteristic of nanofibers are their long length, high porosity and large surface area. The features are makes them widely applicable in electric and optical devices, optoelectronic components, optical waveguides, gas storage units, fluidic devices, tissue engineering scaffolds and bioreactors. In this century, exciting and important research areas for nanofibers application are in energy technology, catalysis and environmental science [59]. Such applications of nanofibers are briefly discussed

Highly porous and large surface area bearing electrospun nanofibers prominently used as solid supports in catalysts. Nanofibers of some materials having excellent semiconducting property make them suitable in photo-catalysts for removing

**28**

**Figure 4.**

*Basic applications of nanofibers.*

organic molecules from air flow or aqueous solution. The extent of catalysis and its efficiency is governed by surface area of the catalyst. Ceramic nanofibers possess extraordinarily high specific surface area are nice materials for their application as catalyst for chemical reaction. The ceramic nanofibers mats of Titanium dioxide (TiO2), zirconium dioxide (ZrO2) and tin dioxide (SnO2) have been employed as support material for loading noble metal nanostructures catalysis in different applications [60]. The membranous catalytic system have distinctive benefit over other process in terms of its operation in a continuous flow mode, relatively short reaction time and even more importantly it need not separation of product after completion of reaction. In addition to large surface area, the support material should also be stable and good conductor of electron. The nanoparticles catalyst of noble-metal Pt, Pd, Rh etc. are homogeneous spread on solid support of carbon black for maximizing possible surface site availability [61]. The Pd-coated Titanium dioxide (TiO2) nanofibers performed well in cross-coupling reaction [62]. It is interesting that the ceramic nanofiber substrate can pointedly influence noble-metal catalyst deposition [63].

#### **5.2 Nanofibers application in energy technology**

Energy shortage is one of the most serious issues of the 21st century because of limited natural energy resources like crude oil, natural gas, coal and uranium that are fulfilling the energy need for everyday life at presented. For rapid economic growth, will require subsequent increase in energy demand mean but the rate of oil production will no longer be adequate. This is evident from the rising price of crude oil. Presently, large volumes of carbon dioxide emitted by industrial burning of fossil fuels are deteriorating climate of the globe. So, it is necessity of the time to identify alternate environmentally friendly new sources of energy that are able to replace current energy supply. The people are trying to converse energy from renewable sources such as the sun, wind, and tides. The most promising energy conversion/storage devices likely to fulfill the need are based on photovoltaic cells, lithium batteries, and fuel cells. For example, Mai and colleagues demonstrated high performance lithium ion battery electrode based on electrospun vanadium oxide nanofibers [64]. They were able to prepare ultra-long hierarchical vanadium oxide nanowires of fine diameter (100–200 nm) and several millimeters using the low-cost starting materials by ES combined with annealing. The 1D characteristic of electrospun ceramic nanofibers have been widely explored as a new class of promising building blocks for fabricating the devices. Energy storage devices are becoming a very common in everyday life of public due to exponential expansion of digitization. Many devices need stored energy for their functions are electronic mobile, autonomous sensors and various kind of vehicle. So, the reliable energy storage devices with high power density and structural integrity are in demand for their use in various devices [65, 66]. Green flexible network of carbon nanofiber can be deriving from abundantly available but underutilized bioresources lignin. The PVA lignin nanofiber network showed has surface area of 1670m<sup>2</sup> per gram and excellent specific gravimetric capacitance of ~240 F per gram that was better than many nanostructured carbon or metal oxides [67]. The carbon based nanofibers have high specific electrical double layer capacitance at low cost [68].

#### **5.3 Nanofibers application in environmental science**

#### *5.3.1 Nanofiber-based membrane for filtration*

Electrospun ceramic nanofibers membranes are able to remove suspended particulate matter from air and other impurities dissolved in water. The highly porous membrane structures, formed by entanglements of nanofibers facilitate material transport without causing resistant to gaseous stream flow or flow of aqueous solution; can be utilized for environmental applications. Dai et al. [50] prepared a hierarchically structured potassium manganese oxide (KxMnO2) / Titanium dioxide (TiO2) mats for filtering Congo red dye from waste water. The membranes not only performance well but also showed high filtering efficiency and robustness survival against strong sheer force of solution flowing through it. In another investigation, Song and co-workers reported synthesis of ultrafine porous carbon nanofibers membrane efficiently removing sulfur dioxide (SO2) from stream of gases. Doping of membranes with minute quantity of nitrogen is likely to improve their capacity, efficiency and durability [69].

#### *5.3.2 Nano-sensors*

Detection of threats to the environment is a key feature of environmental management strategy. The contaminants posing environmental threat could be detected with the help of sensors. Some semiconducting materials like Titanium dioxide (TiO2), SnO2, zinc oxide (ZnO), tungsten oxide (WO3), molybdenum oxide (MoO3) have been shown to detect trace level of gaseous species in the parts per million levels [70]. The sensing ability of such materials could be enhanced by increasing specific surface area and porosity. The 1D architectures of nanofiber facilitate fast mass transfer near molecular interaction region and traverse of barriers by charge carriers. Nanofibers of Titanium dioxide (TiO2), iron oxide (Fe2O3), SnO2, ZnO/SnO2, lithium chloride (LiCl)/TiO2, Titanium dioxide (TiO2)/ZnO, potassium chloride (KCl)-doped-ZnO, and Co-doped-ZnO are successfully employed in sensing and enhanced limit of detecting gaseous species. The gases or vapors notably detected are hydrogen (H2), carbon monoxide (CO), O2, nitrogen dioxide (NO2), ammonia (NH3), H2O, methanol (CH3OH), ethanol (C2H5OH) and toluene. Wang and colleagues reported very quick response of electrospun orthorhombic-phase WO3 nanofiber's high sensitivity to different concentrations NH3 [71]. The superior sensing performance of the material was attributed to high purity, preparation method, high surface area per unit volume and porosity for good accessibility of the gas. The electrospun ceramic nanofibers not only function as sensing materials, but also act as good support material for other sensing bodies derived from noble metal.

#### *5.3.3 As photo-catalysts*

Current environmental issue of air and water pollution motivate for sustained fundamental and applied research for remediation of different polluted ecosystem. The steadily growing field of nanoscience research is engaged in synthesizing nanostructured ceramics as photo-catalyst. The low cost and environmental friendliness compounds, ZnO and Titanium dioxide (TiO2), have showed high catalytic activity are promising photocatalytic material. These small sized and extremely high surface area containing ceramic nanofibers provide channels for quick charge transfer due to its 1D nanostructure. Such ceramics nanomaterial could be potentially used in photo catalysis. Zhang and coworkers synthesized hybrid Fe-Titanium dioxide (TiO2) /tin dioxide (SnO2) nanofibers having high photo-catalytic activity and ferromagnetic properties at room temperature. It is supposed that this hybrid nanofiber can act new generation of visible light-excitable photo catalyst with easy recyclable and its potential predictable applications in water purifying and other pollution treatment [72]. Recently, Yoshikawa and colleagues showed Titanium dioxide (TiO2) nanofibers potentially application as photo-catalysts for H2 production [73]. The novel structured highly crystalline nanomaterial might be able to

**31**

*Green Synthesis of Nanofiber and Its Affecting Parameters*

reduce lattice defects to facilitate the electron transport for reactions with water adsorbed on their surface. During synthesis and producing of dyes, about 16% of the total global productions are lost with wastewater [74]. A variety of bioremediation techniques are utilize for dye elimination such as Enzymes, Microbiological decolorization. The common pollutants (organic/inorganic) present in aquatic atmosphere are due to the discharge of wastewaters from households as well as from the manufacturing sectors. These contaminants, organic molecules might be found in the land and surface water. The elimination of carcinogenic, non-biodegradable organic dyes and other chemicals from the surroundings is a central environmental

Pollution of ground and surface water across the world is now critical issue. Heavy metals are the important pollutants that affect physiology of lining entities significantly. The heavy metals frequently reported in the polluted water bodies are As, Cu, Hg, Cd and Pb. The elements are released in industries waste that are discharged and distribution in the environment and finally enter in water. e.g. Smelting of copper release high quantities of Cd in its industrial wastewater. It is nearly impossible to eliminate some metals contaminants from water using conventional water purification procedure. The nanotechnology has greatly advanced water and wastewater treatment potential. They facilitate improved safe use of unconventional water sources. The limited surface area containing conventional adsorbents bear less active sites and also lack of selectivity. In contrast nano sorbents with enhancement specific surface area and large number of available sorption sites, small intra-particle diffusion distance, tunable pore size and surface chemistry facilitate better adsorption. In future, suitable polymer nanofibers functionalized ceramic membranes can be used for fabricating affinity membranes for treating heavy metal containing industrial waste water [76, 77]. The discharge of heavy metals like arsenic, cadmium, chromium, cobalt, nickel, copper, silver, tin, titanium, lead and zinc, into the environment of textile production is an immense concern all over the global because these metals pose unfavorable effects on the

Green synthesis of composite nanofibers can be successfully prepared using sol–gel and ES technique using polymer solutions. Some of the characteristics of the synthesized green composite nanofibers are their controlled average diameter distribution in desired range, remarkably straight fiber over several micrometers of length, uniform and smooth surface. Generally, viscosity of the casting solution plays the most important role in the fiber morphology and diameter. The green syntheses of nanofibers are affected by solution parameters, process parameters and ambient parameters. The nanofibers are at the forefront of nanotechnology due to their merits and suitability to wide range of applications in the field of healthcare, biotechnology, energy storage, environmental engineering, defense and security.

The authors acknowledge Birla Institute of technology, Mesra, Ranchi, Jharkhand and Indian Institute of Technology (BHU), Varanasi for characterization

human being health, natural atmosphere and aquatic living.

*DOI: http://dx.doi.org/10.5772/intechopen.94539*

*5.3.4 Water and wastewater treatment*

problem [75].

**6. Summary**

**Acknowledgements**

#### *Green Synthesis of Nanofiber and Its Affecting Parameters DOI: http://dx.doi.org/10.5772/intechopen.94539*

*Nanofibers - Synthesis, Properties and Applications*

*5.3.2 Nano-sensors*

*5.3.3 As photo-catalysts*

porous membrane structures, formed by entanglements of nanofibers facilitate material transport without causing resistant to gaseous stream flow or flow of aqueous solution; can be utilized for environmental applications. Dai et al. [50] prepared a hierarchically structured potassium manganese oxide (KxMnO2) / Titanium dioxide (TiO2) mats for filtering Congo red dye from waste water. The membranes not only performance well but also showed high filtering efficiency and robustness survival against strong sheer force of solution flowing through it. In another investigation, Song and co-workers reported synthesis of ultrafine porous carbon nanofibers membrane efficiently removing sulfur dioxide (SO2) from stream of gases. Doping of membranes with minute quantity of nitrogen is

Detection of threats to the environment is a key feature of environmental management strategy. The contaminants posing environmental threat could be detected with the help of sensors. Some semiconducting materials like Titanium dioxide (TiO2), SnO2, zinc oxide (ZnO), tungsten oxide (WO3), molybdenum oxide (MoO3) have been shown to detect trace level of gaseous species in the parts per million levels [70]. The sensing ability of such materials could be enhanced by increasing specific surface area and porosity. The 1D architectures of nanofiber facilitate fast mass transfer near molecular interaction region and traverse of barriers by charge carriers. Nanofibers of Titanium dioxide (TiO2), iron oxide (Fe2O3), SnO2, ZnO/SnO2, lithium chloride (LiCl)/TiO2, Titanium dioxide (TiO2)/ZnO, potassium chloride (KCl)-doped-ZnO, and Co-doped-ZnO are successfully employed in sensing and enhanced limit of detecting gaseous species. The gases or vapors notably detected are hydrogen (H2), carbon monoxide (CO), O2, nitrogen dioxide (NO2), ammonia (NH3), H2O, methanol (CH3OH), ethanol (C2H5OH) and toluene. Wang and colleagues reported very quick response of electrospun orthorhombic-phase WO3 nanofiber's high sensitivity to different concentrations NH3 [71]. The superior sensing performance of the material was attributed to high purity, preparation method, high surface area per unit volume and porosity for good accessibility of the gas. The electrospun ceramic nanofibers not only function as sensing materials, but also act as good support material for other sensing bodies derived from noble metal.

Current environmental issue of air and water pollution motivate for sustained fundamental and applied research for remediation of different polluted ecosystem. The steadily growing field of nanoscience research is engaged in synthesizing nanostructured ceramics as photo-catalyst. The low cost and environmental friendliness compounds, ZnO and Titanium dioxide (TiO2), have showed high catalytic activity are promising photocatalytic material. These small sized and extremely high surface area containing ceramic nanofibers provide channels for quick charge transfer due to its 1D nanostructure. Such ceramics nanomaterial could be potentially used in photo catalysis. Zhang and coworkers synthesized hybrid Fe-Titanium dioxide (TiO2) /tin dioxide (SnO2) nanofibers having high photo-catalytic activity and ferromagnetic properties at room temperature. It is supposed that this hybrid nanofiber can act new generation of visible light-excitable photo catalyst with easy recyclable and its potential predictable applications in water purifying and other pollution treatment [72]. Recently, Yoshikawa and colleagues showed Titanium dioxide (TiO2) nanofibers potentially application as photo-catalysts for H2 production [73]. The novel structured highly crystalline nanomaterial might be able to

likely to improve their capacity, efficiency and durability [69].

**30**

reduce lattice defects to facilitate the electron transport for reactions with water adsorbed on their surface. During synthesis and producing of dyes, about 16% of the total global productions are lost with wastewater [74]. A variety of bioremediation techniques are utilize for dye elimination such as Enzymes, Microbiological decolorization. The common pollutants (organic/inorganic) present in aquatic atmosphere are due to the discharge of wastewaters from households as well as from the manufacturing sectors. These contaminants, organic molecules might be found in the land and surface water. The elimination of carcinogenic, non-biodegradable organic dyes and other chemicals from the surroundings is a central environmental problem [75].

## *5.3.4 Water and wastewater treatment*

Pollution of ground and surface water across the world is now critical issue. Heavy metals are the important pollutants that affect physiology of lining entities significantly. The heavy metals frequently reported in the polluted water bodies are As, Cu, Hg, Cd and Pb. The elements are released in industries waste that are discharged and distribution in the environment and finally enter in water. e.g. Smelting of copper release high quantities of Cd in its industrial wastewater. It is nearly impossible to eliminate some metals contaminants from water using conventional water purification procedure. The nanotechnology has greatly advanced water and wastewater treatment potential. They facilitate improved safe use of unconventional water sources. The limited surface area containing conventional adsorbents bear less active sites and also lack of selectivity. In contrast nano sorbents with enhancement specific surface area and large number of available sorption sites, small intra-particle diffusion distance, tunable pore size and surface chemistry facilitate better adsorption. In future, suitable polymer nanofibers functionalized ceramic membranes can be used for fabricating affinity membranes for treating heavy metal containing industrial waste water [76, 77]. The discharge of heavy metals like arsenic, cadmium, chromium, cobalt, nickel, copper, silver, tin, titanium, lead and zinc, into the environment of textile production is an immense concern all over the global because these metals pose unfavorable effects on the human being health, natural atmosphere and aquatic living.

### **6. Summary**

Green synthesis of composite nanofibers can be successfully prepared using sol–gel and ES technique using polymer solutions. Some of the characteristics of the synthesized green composite nanofibers are their controlled average diameter distribution in desired range, remarkably straight fiber over several micrometers of length, uniform and smooth surface. Generally, viscosity of the casting solution plays the most important role in the fiber morphology and diameter. The green syntheses of nanofibers are affected by solution parameters, process parameters and ambient parameters. The nanofibers are at the forefront of nanotechnology due to their merits and suitability to wide range of applications in the field of healthcare, biotechnology, energy storage, environmental engineering, defense and security.
