Chapter-2 Review of literature

School of Chemistry 25

REVIEW OF LITERATURE

Nanotechnology has been used to develop nanomaterials, nanodevices and various

nanosystems. The nanomaterials are the most advanced in scientific knowledge as

well as in commercial applications. Reduction in the size of nanoparticles brings

significant changes in their physical properties in comparision to bulk materials (Rana

and Kalaichelvan, 2013).

2.1. Different Methods for the Synthesis of Nanomaterials

It has been observed that each micelle in the microemulsion as a “nano-reactor”

(Ganguli et al., 2010). Wongpisutpaisan et al., (2011) used copper nitrate trihydrate,

sodium hydroxide, polyvinyl alcohol as starting precursors for synthesis of copper

oxide nanoparticles. Zinc oxide nanoparticles were fabricated from zinc acetate

solution in aqueous methanol and isopropanol. The rod like particles of size in the

range between 21 and 28 nm were observed (Banerjee et al., 2012). Darrouudi and

coworkers (2012) studied the formation of silver nanoparticles from silver nitrate and

hydrochloric acid. The effect of different parameters on the particle size has been

investigated. It has been observed that the size of the Ag-NPs decreased with the

ultrasonic amplitude and increases with ultrasonic time. Well-dispersed spherical Ag-

NPs with particle size of 3.5 nm were formed.

Zhu and coworkers (2004) synthesized copper nanoparticles using copper sulphate as

a precursor and sodium hypophosphite as the reducing agent in ethyl glycol under

microwave irradiation. They studied the effect of some parameters like concentration

of reducing agent and microwave irradiation time on the copper nanoparticles. The

size of copper nanoparticles was abserved to be 10 nm. Recently, Sutradhar et al.

(2014) reported the synthesis of copper oxide nanoparticles using tea leaf and coffee

powder extracts under microwave irradiations at 540 W with in 7–8 min. Barreto et

al. (2013) prepared zinc oxide nanoparticle via microwave irradiation at different

temperature 80, 100, 120, or 140°C using sodium di-2-ethylhexyl-sulfosuccinate

aqueous solution, NaOH, KOH and NH4OH as precursor salt. Ha et al., (2013) used

microwave irradiation approach for the synthesis of ZnO nanopowders in mixture of

Chapter-2 Review of literature

School of Chemistry 26

zinc acetate and propanol. Blosi et al. (2004) reported the microwave-assisted polyol

synthesis of crystalline particles of size removed from 90 nm to 260 nm.

Gold, platinum, silver and palladium nanoparticles have been studied extensively via

laser ablation method (Singh et al., 2012). The change in shape of gold nanoparticles

was observed from spherical to elliptical. Kubiliute et al. (2013) has reported a

change in the shape of the gold nanoparticles by laser ablation method. Zinc

nanoparticles were prepared using laser ablation of metal plate in an aqueous solution

and average particles size obtained was 14⋅7 nm (Singh et al., 2007). Gondal et al.

(2011) applied laser ablation method for the growth of nano metal oxides such as

ZnO, ZnO2, SnO2, Bi2O3, NiO and MnO2. Maneeratanasarn et al. (2013) reported the

fabrication of α-Fe2O3 in ethanol, water and acetone medium. Laser ablation of the

iron oxide target in ethanol and acetone yields crystalline maghemite (γ-Fe2O3)

nanoparticles, while in distilled water yields amorphous hematite (α-Fe2O3).

Antimony oxide nanoparticles were prepared via laser ablation of an antimony plate

placed on the bottom of quartz vessel filled with double distilled deionized water. The

particles diameter was observed 59 nm (Khalef et al., 2013). Iwamoto et al. (2013)

reported the use of poly(N-vinyl-2-pyrrolidone) as a protective reagent for the

synthesis of different phases iron oxide nanoparticles such as Fe, Fe3O4, and Fe2O3 in

water.

Piriyawong and his coworkers (2012) have studied the formation of

Al2O3 nanoparticles using laser ablation of an aluminum target. SEM images showed

spherical shape particle size less than 100  nm. Furthermore, it was observed that the

particle size increased with the increasing laser energy.

Khan et al. (2008) have reported the generation of NiO nanoparticles in presences of

anionic surfactant sodium dodecyl sulfate. The results revealed the formation of NiO

nanoparticles in water with an average size of 12.6 nm. The addition of anionic

surfactant sodium dodecyl sulfate reduced the size of NiO nanoparticles upto 10.4 nm.

Iron carbide nanoparticles were synthesized in pentane, hexane, or decane solvent.

TEM images showed that the spherical shape nanoparticles with diameters ranged

from 10 to 100 nm (Matsue et al., 2011).

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School of Chemistry 27

Kaatz et al. (1991) has reported the formation of Mo nanoparticles using a sputtering

process with a target-substrate distance of about 9 cm. Carbon nanoparticles were

synthesized via sputtering in a high vacuum. The morphology was studied according

to the positive biasing of a substrate holder. At the bias voltage lower than or equal to

30 V, only nanoribbon-like structures were observed (Bouchat et al., 2011). Asanithi

and coworkers (2012) prepared silver nanoparticles with average particles sizes of

5.9, 5.4 and 3.8 nm via sputtering process. Au nanoparticles were fabricated by

focused ion beam bombardment of thin gold films. Results showed formation of Au

particles with size about 2 nm (Zhou et al., 2009).

Fe3O4 nanoparticles were synthesized via co-precipitation from ferric and ferrous salts

under the N2 gas. TEM image of the Fe3O4 showed particles size of 5-20 nm (Hariani

et al., 2013). Mascolo and his co-worker (2013) prepared magnetite nanoparticles

with particles size of 11.0 nm using NaOH, KOH, (C2H5)4NOH and FeCl2·4H2O

mixture. Arora and Ritu, (2013) synthesized copper oxide nanoparticles using

Cu(NO3)2 and aqueous ammonia solution. The formation of ZnS nanoparticles was

reported via coprecipitation method using various capping agents like

polyvinylpyrrolidone, polyvinylalcohol and polyethyleneglycol. The particle size of

2-4 nm was recorded (Ayodhya et al., 2013). Mukhtar and coworkers (2012) have

studied Cu-doped ZnO particles formation in copper sulfate monohydrate, zinc sulfate

hepta hydrate, sodium hydroxide solution with particle size of 10 - 16 nm.

Transition metal oxides, borides, carbides and silicides were synthesized via ball

milling (Basset et al., 2005). Zirconia balls with diameters of 2 mm and 5 mm using

ball milling in the mixture of n-heptane or ethanol as a grinding medium and oleic

acid was reported.

It has been observed that the size of particles decreased with milling speed and time.

The particle sizes were found in the range of 30-60 nm. Recently, Hakim et al. (2015)

have prepared nanocrystals of PrBaY2F8 with average diameter of 24 nm using ball

milling method. Nanoparticles of Fe, Co, FeCo, SmCo, and NdFeB systems with sizes

smaller than 30 nm have been synthesized by ball milling in the presence of heptane

used as a solvent and oleic acid and oleyl amine as surfactants (Chakka et al.,

2006). Akl and coworkers (2013) studied the effect of parameters on the synthesis of

silica nanoparticles via milling process. The formation of SiO2 NPs with particle size

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School of Chemistry 28

ranging of 22-48 nm was observed. Zinc oxide nanoparticles were reported by ball

milling and showed that the particle size decreased from 600 to 30 nm with milling

time (Salah et al., 2011).

2.1.1. Electrochemical Method

Electrochemical synthesis of gold nanoparticles using tetradodecylammonium

bromide surfactant as stabilizer, have been reported earlier (Huang C.J., 2006).

Monodispersed gold has been fabricated in hexadecyltrimethylammonium bromide

and tetradodecylammonium in acetone solvent (Huang et al., 2006).

The electrodepostion of Cu nanorod has been reported on sacrificial copper anode by

electrolyzing acetone and cyclohexane solution in the presence of

hexadecyltrimethylammonium bromide and tetrabutylammonium bromide electrolyte

(Yang et al., 2003). The electrodepostion of copper nanoparticles has been studied by

electrolyzing acetonilrile solution, tetrabutylammonium nitrate and chilone chloride

solution (Vidal et al., 2010). Sacrificial palladium anode has been used for the

prepration of palladium NPs in morpholinium ionic liquid and acetonitrile solution

(Cha et al., 2007).

Nickle single and multilayer nanowires have been electrodeposited on anodic

aluminum oxide (Joo et al., 2006). Hamrakulov, (2009) reported the diameters of

nickle single and multilayer nanowires in anodic alumina templates of 40−80 nm in

NiSO4.6H2O, H3BO3 and KCl solution (Li et al., 2009).

Copper nanowires have been fabricated by electrochemical deposition using porous

anodic alumina templates using copper sulphate and sulfuric acid solution

(Hamrakulov et al., 2009). Copper nano wires have been synthesized using

polycarbonate template (Tian et al., 2003). The inert anodic electrodepostion of

copper nanoparticles have been prepared by electrolysis of copper sulfate using

NaBH4 as reducing agent and polyvinylpyrrolidone as stabilizer under nitrogen

atmosphere (Hashemipour et al., 2011).

Chang et al. (1999) demonstrated that gold nanorods were formed in high yields in

the presence of cyclohexane additive. Gold nanorods have been fabricated with a

crooked structure by addition of isopropanol solvent (Chang et al., 1999). Gold

nanoparticles with different shapes such as nanorods, nanotubrs, and nanowires have

Chapter-2 Review of literature

School of Chemistry 29

been synthesized electrochemically (Zhu et al., 2011) and dumbbell, spheroid and

rod-like AuNPs (Shen et al., 2005). Electrodepostion of Ag nanoparticles has been

studied onto carbon coated TEM grids, indium tin oxide and coated glass substrate in

H2SO4 and HAuCl4 solution (Hu et al., 2011).

Palladium nanoparticles, nanowires and nanorods were synthesized electrochemically

onto a carbon surface using carbon nanotubes, alumina membranes and glassy carbon

electrodes as substrate (Bliznakov et al., 2011). These supported substrates enhanced

the mechanical and thermal stability of metal nanoparticles and also maintained the

highly dispersed state (Qi and Pickup, 1998). Deposition of platinum on carbon

matrixes such as, carbon, glassy carbon, carbon black, carbon nanotubes, diamond

substrates and graphite have been attempted (Hu et al., 2009). Lupu et al. (2012) have

reported platinum NPs electrodeposited on poly(3,4-ethylenedioxythiophene). Wang

and co-workers (2005) reported the electrochemical fabrication of Zn nanowires on

polycarbonate or anodic aluminum oxide membranes with diameters between 40 and

100 nm.

Platinum nanoparticles have been prepared in presence of aqueous solutions of NaOH

and cathodic corrosion processes increased in electrolyte concentration (Yanson et al.,

2013). The inert cathodic electrochemical deposition of ZrOCl2 and YCl3 salts has

been used to achived by cathodic electrodeposition of pure zirconia and yttria-doped

zirconia films using ethyl alcohol-water solvent (Zhitomirsky and Petric, 2002). The

electrolysis reaction at Ti anode were performed using water, NH4F, and ethylene

glycol as electrolytes and TiO2 nanotube with diameters of 70 and 180 nm (Kant and

Losic, 2011).

Literature review revealed that anodic oxidation reaction has been carried out in

aqueous sulfate solution at sacrificial Ag wire anode at 100 mA to produce silver

oxide nanoparticles (Murray et al., 2005)

Electrochemical oxidation of ethanol solution containing LiCl and water has been

carried out for the synthesis of zinc nanoparticles (Starowicz and Stypuła, 2008).

Chandrappa et al., 2010 have reported anodic electrochemical reaction at sacrificial

Zn anode and cathode in an undivided cell in aqueous sodium bicarbonate electrolyte

at current density 0.05 to 1.5 A/dm2 to produce ZnO nanoparticles of 30-40 nm size.

Chapter-2 Review of literature

School of Chemistry 30

ZnO nanocrystals were synthesized at Zn anode electrolyzed in sodium citrate and

H2O–EtOH solution (Yuan et al., 2012).

Recently, Chandrappa and coworkes (2013) studied the formation of Zn2SnO4

nanoparticles in presences of sodium bicarbonate and sodium stannate electrolyte at

Zn anode. The reaction scheme suggested of the preparation of Zn2SnO4 is as follows:

At anode

Zn Zn2+

+ 2e-

At cathode

2H+ + 2e

- H2

In electrolytic solution

2NaHCO3 + 2H2O 2Na+ + OH

- + 2CO2 + H2

Na2SnO3 + 3H2O Sn4+

+ 2Na+ + 6OH

-

Zn2+

+ Sn4+

+ 6OH- ZnSn(OH)6

Zn2+

+ 4OH- Zn(OH)4

2-

After calcination

ZnSn(OH)6 + Zn(OH)42-

Zn2SnO4 + 4H2O + 2OH-

Figueroa and co-workers (1993) contributed principal reaction in the electrochemical

process of copper oxide using anode support system as follows:

At anode

Cu + nCl- CuCln

1-n + e

- (n= 2, 3)

At cathode

2H2O + 2e- H2 + 2OH

-

2CuCln1-n

+ 2OH- Cu2O + 2nCl

- +H2O

2Cu + H2O Cu2O + H2

Cu2O crystals with various morphologies have been synthesized at sacrificial Cu

anode in the presence of surfactants at current density, temperature etc. (Barton,

2001). Electrochemical oxidation of CuO nanoparticles formation in aqueous sodium

nitrate bath occured as follows (Yuan et al., 2007):

At anode

Cu Cu2+

+ 2e-

At cathode

Chapter-2 Review of literature

School of Chemistry 31

NO3- + H2O + 2e- NO2

- + 2OH

-

In electrolytic solution

Cu2+

+ 2OH- Cu(OH)2

Cu(OH)2 CuO + H2O

Pandey and coworkers (2012) have reported the anodic oxidation at sacrificial copper

anode in presence of KCl/H2O2 supporting electrolyte at 200 and 400 mA current. The

mechanism of copper (II) oxide NPs formation is as followed.

At anode

Cu Cu2+

+ 2 e-

At cathode

Cu++

+ 2e- Cu

Cu + 2H2O CuO + H2O + 2e-

2H+ + 2e

- H2

In electrolytic solution

2H2O 2H+ + 2OH

-

KCl K+ + Cl

-

Cu2O nanowires were reported by electrolyzing the solution of CuSO4 in lactic acid,

CuSO4 and H3BO3 solution at inert porous alumina template as anode (Iida et al.,

2011). Similarly, nanofibrous vanadium oxide was prepared anodically from aqueous

solutions containing VOSO4 and NaSO4 (Douglas et al., 2008).

Inert anodic electrolysis of aqueous silver acetate using inert stainless steel,

polycrystalline platinum and indium-tin oxide-coated glass anode has been attempted

to produces silver oxide nanoparticles (Breyfogle et al., 2008).

Lee and Tak (1999) used indium tin oxide substrate to produce yttrium oxides

nanoparticles via electrochemical deposition. Inert anodic reaction was carried out in

VOSO4/H2O2 solution to yield vanadium oxide (Hu et al., 2008). Nickel oxide film

has been synthesized using anodic electrodepostion process on conducting indium tin

oxide coated glass substrate in aqueous solution (Sung and Yang, 2007). Genki et al.,

(2012) prepared CuO nanoflowers using copper wire as a cathode in solution of

K2CO3, NaCl, citrate buffer and K2Cr2O7. The size of particles obtained in the range

between 32 and 35 nm.

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School of Chemistry 32

The inert cathodic electrodeposition of amorphous Fe2O3 thin films by reduction of Fe

(III) perchlorate in oxygenated acetonitrile has been reported (Zotti, 1998). Schrebler

et al., (2006) reported the electrodeposition of nanocrystalline Fe2O3 thin films at inert

fluorine doped tin oxide substrate using aqueous solution of FeCl3/KF/H2O2. Ferric

hydroxides have been transformed to Fe2O3 by the thermal annealing in air.

The electrochemical reduction of Ti cathode in aqueous solutions resulted the

formation of crystalline thin films of TiO2 under room temperatures (Natarajan and

Nogami, 1996).

Yoshida et al. (2004) have prepared ZnO film electrolyzed in a Zn(NO3)2 aqueous

solution. It has been revealed that the nanostructure strongly depends on the micelle

structure of surfactants which is variedly controlled by electrodeposition conditions

such as electrode potential, molecular structure of surfactant and surfactant

concentration. Inert cathodic electrodeposition of ZnO nanoparticles was performed in

an anionic surfactant solution (Usui, 2011).

Cathodic electrodeposition of iron oxide nanoparticles at gold plate as anode and a

pure aluminum substrate as cathode in aqueous electrolytic bath with particle size

ranged from 20 to 60 nm have been reported. Mechanism of cathodic deposition of

iron oxide/hydroxide is based on the generation of OH− ions at inert cathode in nitrate

solution as follow (Yousefi et al., 2013):

At cathode

NO3−

+ H2O + 2e- NO2

− + 2OH

−

NO3−

+ 7H2O + 8e- NH4

+ + 10OH

−

O2 + 2H2O + 4e- 4OH

−

In electrolytic solution

2Fe3+

+ 6OH−

2Fe(OH)3

2Fe(OH)3 Fe2O3 + 3H2

Inert cathodic electrochemical reaction of aqueous Y(NO3)3 and YCl3 salt solutions

in poly(diallyldimethylammonium chloride) yield Y2O3 film (Zhitomirsky and

Chapter-2 Review of literature

School of Chemistry 33

Petric, 2000). Lee and Tak, (1999) used indium tin oxide electrode as cathode to

prepare yttrium oxide films in Y(NO3)3.4H2O solution.

Cui et al. (2012) generated CdO nanosheet film electrolyzed with Cd(NO3)2 and

HNO3 as source materials. Ebrahimi et al., (2012) have carried out inert cathodic

electrolysis at polyethylene glycol template and electrolyzed aqueous solution of

PbNO3 to synthesize lead oxide nanodendrites.

2.2. Nanocomposites

Nanoparticles embedded in host polymer have gained significant interest in the recent

years. Nanocomposites have been achived by thermolysis, photolysis, radiolysis and

chemical reduction of metallic precursor dissolved the polymer. In ex-situ approach,

nanoparticles are first synthesized by soft-chemical routes and then dispersed in the

polymeric matrices (Barbucci et al., 2009). Recently, the nano composites were

prepared using ex-situ approach of natural or synthetic polymers (Barbucci et al.,

2009). Natural polymer most commonly used starch, cellulose, chitosan, carrageenan,

alginate, agarose and guar gum etc. The natural polymer gained a substantial

importance for development of nanocomposite in diverse field such as transporation,

electronics, promoting thermal, mechanical, antibacterial, photochatalytic, adsorption,

drug delivery and other consumer products (Ganguli et al., 2008). Inorganic and

organic components can be mixed at the nanometer scale for formation of the hybrid

organic-inorganic nanocomposites (Loy et al., 1995). The properties of hybrid

materials do not depend only on both the organic and inorganic components but also

on the interface between both phases.

Silver/montmorillonite/chitosan bionanocomposites have been reported using

chemical reduction method. AgNO3, MMT, Cts, and NaBH4 were used as silver

precursor, the solid support, the natural polymeric stabilizer and chemical reduction

agent, respectively (Shameli et al., 2011). Ahmad et al., (2012) reported the

incorporation of silver nanoparticles into biodegradable chitosan, gelatin via chemical

reduction method. Retuert et al. (2004) studied the gelatin/silica composite synthesis

by mixing gelatin and silicate solutions followed by precipitation with hydrochloric

acid. Silver/poly(vinylalcohol) nanocomposites were prepared from silver salt using

two different reducing agents hydrazine hydrate and sodium formaldehyde

Chapter-2 Review of literature

School of Chemistry 34

sulfoxylate. The particle size was found less than 10 nm (Khanna et al., 2005).

Cu/multi-walled carbon nanotubes composite with particle size ranging from 20–

50 nm has been synthesized using sodium borohydride as a reducing agent and copper

sulphate as the precursor material (Singhal et al., 2012). Boomi et al. (2013)

synthesized polyaniline/Au and polyaniline/Au–Pd nanocomposite using Au and Au–

Pd colloidal solutions with ammonium persulphate as an oxidizing agent. The

resultant particle size range between 3 and 18 nm.

Titanium dioxide and vanadium dioxide nanocomposites were synthesized from the

deposition of VCl4 and Ti(OiPr)4 at 650 °C with rectangular vanadium dioxide and

spherical titanium dioxide of varying diameters (Qureshi et al., 2006). Mungkalasiri et

al. (2009) have reported nanocomposite of TiO2 containing copper nanoparticles

using titanium tetraisopropoxide and copper bis (2,2,6,6-tetramethyl-3,5-

heptadionate) as organometallic precursors. Nanocomposites were deposited on glass,

silicon and steel substrates with metal particles size between 20 and 400 nm.

Cobalt hybrid/graphene nanocomposite has been synthesized via hydrothermal

synthesis using NaBH4 as a reducing agent (Wang et al., 2013). Tomar et al. (2013)

have synthesized TiO2-ZrO2 nanocomposite via hydrothermal method. ZnO/reduced

graphene oxide composite has been prepared by hydrothermal process in aqueous

suspension containing Ag and ZnO with graphene oxide sheets at 140 ºC for 2h.

Graphene/ZnO nanocomposites have been synthesized at two different temperatures

80 and 90 °C (Saravanakumar et al., 2013). Ti(SO4)2 and SnO2-TiO2 nanocomposites

were prepared using SnCl4·5H2O and urea at 80–100 °C in aqueous solutions. The

particles obtained with an average diameter of about 52.2 nm (Wang et al., 2013).

Rajendran et al. (2013) reported the chitosan/ZnO composites by hydrothermal

method using commercial chitosan, zinc nitrate and sodium hydroxide within the

micrometer scale.

Poly(N-isopropyl acrylamide) grafted mesoporous silica nanoparticle has been

synthesized in an aqueous medium without additives like cross-linker, hydrophobic

agent, organic solvent. The particle size varied between 160 and 180 nm (Chowdhury

et al., 2012).

Nanocomposites of conducting polyaniline (PANI) and montmorillonite (MMT) have

been synthesized by expand the basal spacing of the anilinium–MMT intercalation

Chapter-2 Review of literature

School of Chemistry 35

compound from 0.96 to 2.47 nm by adding anilinium chloride using intercalation

method. After polymerization decrease in the basal spacing to 1.33 nm indicate that

PANI was synthesized between the interlayer spaces of MMT (Shoji Yoshimoto et

al., 2004).

Mehrotra and Giannelis, 1991 reported that polyaniline formed by

polymerizing aniline in the interlayer space exposure to HCl vapour. The emulsion

and bulk polymerization methods have been reported for the preparation of

polystyrene/clay nanocomposites using the Na-MMT, cloisite 30B and cloisite 15A

clay materials. Polyaniline/MMT nanocomposites were prepared by polymerization of

aniline in the presence of MMT (Olad and Rashidzadeh, 2008). Polyaniline/ clay

nanocomposites were synthesized by intercalation of anilinium ion into the clay in

presences of sodium montmorillonite, anilinium hydrochloride ammonium

peroxysulfate lead at room temperature (Kalaivasan et al., 2010).

2.2.1. Sol-gel method

Cannas et al. (2004) synthesized ferrite-silica nanocomposites by a sol-gel using

autocatalytic oxidation-reduction reaction between nitrate and citrate ions. The carbon

nanotube/alumina nanocomposite has been successfully fabricated via sol-gel process

(Mo et al., (2005). Homogeneous distribution of carbon nanotubes within alumina

matrix has been obtained by condensation into gel.

ZnO/SnO2 nanocomposites have been prepared using sol-gel method by mixing of

ZnO to SnO2 followed by hydrolysis and condensation reaction. The average particle

size was found to be about 23–97 nm (Talebian et al., 2011). Ashkarran et al. (2011)

have synthesized Ag/TiO2 nanocomposite with uniformly dispersed Ag nanoparticles

with in TiO2 matrix. The particle size was found to be 10-12 nm.

Recently, Yadav et al. (2015) prepared PbS–Al2O3 nanocomposites using lead acetate

material, thiourea and aluminium isopropoxide at 80 ºC of particles size varied from 2

to 40.5 nm. Nanocomposite of cobalt–silicon oxides were prepared using

Co(NO3)2·6H2O and Si(OC2H5)4 in the presence of nitric acid as catalyst at 110 ◦C for

12 h (Bagnasco et al., 2008). Copper, nickel and iron-based metal oxide

nanocomposites via sol–gel using their metal nitrate in the presence of glycolic acid

and ammonia were reported. The particle size of the nanocomposite was found in the

Chapter-2 Review of literature

School of Chemistry 36

range between 10 and 120 nm (Srivastava et al., 2010). Nanocomposite of

maleimideepolystyrene with SiO2 and Al2O3 was reported in the presence of g-

aminotriethoxysilane, tetraethoxysilane and aluminum isopropoxide as precursors,

particle size were ranged from 20 to 50 nm (Ramesh et al., 2015).

Polyaniline aand polyacrylamide based nanocomposite has been reported for the

removal of pollutants from water system (Pathania et al., 2014a, 2014b). TiO2

coupled TiO2/bamboo charcoal (TiO2-TiO2/BC) was prepared via sol-gel method

using titanium isopropoxide, ammoniumperoxodisulphate and montmorillonite K-10

mixture (Sandhyaa et al., 2013). Kavitha et al., (2013) reported titania–chitosan

nanocomposites by mixing titanium isopropoxide, isopropyl alcohol, acetyl acetone

and chitosan. The particles showed anatase phase, spherical and irregular morphology

with particle size ranges from 4.5 to 10.5 nm. Cellulose based nanocomposite have

been synthesized by sol–gel method and their physico-chemical properties were

investigated (Rathore et al., 2014).

Pectin based nanocomposite have been studied by mixing biopolymer pectin with

inorganic counterparts using the sol–gel method. The size of particles ranged from

4 nm to 10 nm (Gupta et al., 2013, 2014; Pathania et al., 2015). Guar gum based

nanocomposites have been also reported using sol gel method (Gupta et al., 2014;

Khan et al., 2013).

2.3. Application

2.3.1. Photocatalytic Activity

The environmental pollution a worldwide threat to public health, give rise to new

initiatives for environmental restoration for both economic and ecological causes

(Bhargava and Jahan, 2012). The contaminated water destroys the aquatic life and

reduces its reproductive ability. In the United States, nearly 34.8 million tonnes of

hazardous waste were generated in 2005, mostly in the form of liquid waste (North

American Mosaic).

Removal of organic pollutants from wastewater is of great concern for researchers due

to their harmful effect. Many semiconductors such as TiO2, ZnO, SnO, NiO, Cu2O,

Fe3O4, and CdS show great photocatalytic activity under solar light (Julkapli, et al.,

Chapter-2 Review of literature

School of Chemistry 37

2014). ZnO  NPs have been used effectively for the degradation of several organic

pollutants in presence of sunlight (Pitchaimuthu et al., 2014). Apollo et al. (2014)

used ZnO NPs as photocatalyst for the degradation of methyl orange dye under

sunlight. Konstantinou and Albanis, (2004) reported the degradation of azo dyes

under sun light irradiation with the generation of hydroxyl radicals. Hydroxyl radicals

are nonselective, strong oxidizers and very reactive. The free radicals are able to

oxidize organic compounds in solution.

Many researchers have focused on TiO2 nanoparticle as a photocatalyst for water

treatment. Titanium dioxide and zinc oxide have been frequently studied for their

ability to remove organic contaminants from various media (Poole, and Owens 2003).

ZnO nanoparticles were reported for the photocatalytic degradation of the

environmental pollutants. Zinc oxide nanoparticle was used for photocatalytic activity

for methylene blue degradation (Shen et al., 2008). Resently, Preethi et al. (2015)

used ZnO and iron oxide nano particles for degradation of congo red dye under solar

light. Pitchaimuthu et al. (2014) studied the photocatalytic activity of ZnO powder

and compared with TiO2 (Degussa P25) over Acid Brown 14 as the model pollutant.

Sires et al. (2006) studied the photocatalytic activity of TiO2 films in solar light for

the degradation of malachite green. Huang et al. (2007) used ZnWO4 nanoparticle as

photocatalyst for the degradation of rhodamine B in water and decomposition of

formaldehyde. In addition, Lin and Zhu (2007) explored ZnWO4 as photocatalysts for

the photodegradation of rhodamine B and gaseous formaldehyde.

Vaseem et al. (2008) has successfully used CuO nanoflower for photocatalytic

activity of methylene blue. The photocatalytic activity of CuO films was determined

for the degradation of rose bengal dye (Wang et al., 2009). Cu2O nanocubes for the

degradation of dye brilliant red X-3B under simulated solar light (Ma et al., 2010).

CuO nanoribbons exhibited the RhB photodecomposition because of the exposed high

surface energy crystal plane (Duonghong et al., 1981). Iron oxide nanoparticle was

found most active for the complete degradation of the dye.

The photocatalytic activity of nanoparticles is affected by the fast recombination of

the photogenerate charge carriers which reduces the efficiency of the photocatalytic

processes. In order to overcome this problem, simultaneous doping with two kinds of

atoms or coupling metal with semiconductor of suitable electronic properties has been

Chapter-2 Review of literature

School of Chemistry 38

investigated (Subash et al., 2012). It has been found viable strategy to increase the

charge separation of the photogenerated electron/hole pairs. Thus, many coupled

semiconductor systems have been used as photocatalysts such as ZnO–TiO2, ZnO–

CdS, ZnO–AgBr, ZnO–Ag2S (Krishnakumar et al., 2012; Subash et al., 2012).

Presence of heterojunctions between the two oxides allows an improved charge

separation of the photogenerated electron–hole pairs, due to the differences between

the energy levels of the conduction and valence bands of ZnO and SnO2

nanocomposites (Hamrounia et al., 2014).

Shakir et al. (2012) used MoO3-MWCNT nanocomposites efficiently for the

decompostion of organic contaminants in aqueous solution under natural sunlight

irradiation. CdPdS–PVAc nanofibers exhibited good photocatalytic performance

toward reactive black 5 and reactive orange 16 dyes within very short time (Afeesh et

al., 2012). Recently, Balachandran et al. (2014) performed the photocatalytic

experiments with aqueous solution of acid red 88 with TiO2 and TiO2–SiO2. The

direct photolysis of TiO2 and TiO2–SiO2 contributed to 94.2% and 96.5%

decomposition of acid red 88.

Li et al. (2013) reported that Fe2O3/ Bi2O3 composite exhibit higher photocatalytic

performance toward in decolorization of methyl orange aqueous solution than pure

Bi2O3 under solar light irradiation

Poly(3,4-ethylenedioxythiophene)/zinc oxide nanocomposites have been used for the

photocatalytic efficiency under both UV light than natural sunlight irradiation. The

highest photocatalytic efficiency under UV light (98.7%) and natural sunlight (96.6%)

after 5 h (Abdiryim et al., 2014). Khan et al. (2014) have reported polyaniline based

nanocomposite for photodegradation of methylene blue under solar light. Most

recently, Shanmugam et al. (2015) used graphene-SnO2-PMMA nanocomposite for

the degradation of methylene blue dye under sunlight irradiations 99%. A large

number of non-conventional bio-adsorbents such biopolymers have been employed

for the remove of toxic metals and dyes from water system (Zhao et al., 2012). The

bio-adsorbents are biodegradeable, harmless and abundantly available (Constantin et

al., 2013).

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School of Chemistry 39

Gupta et al. (2012, 2013) synthesized pectin based CuS for photocatalytic degradation

of methylene blue under sunlight irradiated showed 95% degradation.

TiO2/ZnO/chitosan was evaluated for the photocatalytic decolorization of methyl

orange in aqueous solution unde solar light 97% of degradation was observed within

4h (Jiang et al., 2012).

Recently, Gupta et al. (2015) has reported pectin based nanocomposite for

photocatalytic degradation of MB and MG dyes. 89.21 and 79.27% of degradation

were reported with in 3 h of photo irradiation using MB and MG, respectivly.

Pathania et al. (2015) studied pectin based nanocomposite for the photo catalytic

degradation of methylene blue dye in the presence of solar irradiation. It was recorded

that 97.02% of methylene blue dye is degraded after 60 min of irradiation.

Cellulose based nanocomposites were studied for the photocatalytic degradation of

methylene blue dye under solar irradiation. 80% of degradation was reported in 140

min (Rathore et al., 2014; Gupta et al., 2014).

2.3.2. Antimicrobial Activity

Silver nanoparticles have been used as most common disinfectant due to low toxicity

on human cells and high efficiency against microorganisms. Sondi et al. (2004)

reported high antimicrobial activity of silver nanoparticle against Escherichia coli

bacteria. Silver nanoparticle was effective against bacteria due to precipitating

bacterial cellular proteins and blocking the microbial respiratory chain system. Silver

nanoparticles have been found potent agents against numerous species of bacteria

such as Escherichia coli, Enterococcus faecalis , Staphylococcus aureus, Vibrio

cholerae , Pseudomonas aeruginosa , putida, fluorescens and oleovorans , Shigella

flexneri, Bacillus anthracis subtilis and cereus Proteus mirabilis, Salmonella enterica

Typhimuriu, Micrococcus luteus, Listeria monocytogenes and Klebsiella pneumoniae

(Fabrega et al., 2009; Sanchez et al., 2009).

Zinc oxide nanoparticle was tested against Bacillus subtilis, Escherichia coli and

Clostridium bacteria and results showed inhibited bacterial growth (Nawaz et al.,

2011). Adams et al. (2006) reported antibacterial activity of ZnO nanoparticles

against Bacillus subtilis and Escherichia coli. They reported that antibacterial activity

Chapter-2 Review of literature

School of Chemistry 40

remained same under dark or light on Bacillus subtilis bacteria whereas more activity

against Escherichia coli under the light.

Doped zinc oxide nanoparticles were observed as antibacterial activity against

Escherichia coli, Klebsiella pneumoniae, Shigella dysenteriae, Salmonella typhi,

Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus (Nair et al.,

2011).

Premanathan et al. (2011) evaluated the antibacterial activity of zinc oxide

nanoparticles. It was concluded that nanoparticles had a more pronounced effect on S.

aureus as comparesd to E. coli, P. aeruginosa and Fusarium sp. The antimicrobial

activity of titania nanoparticles have been extensively studied and found maximum

activity against Escherichia coli and minimum activity against the fungi Candida

albicans which was related to the complexity of the cell membrane (Kuhn et al.,

2003).

Sadiq et al. (2009) studied that alumina nanoparticles has a mild inhibitory effect

against Escherichia coli even at high concentrations (1000 μg/ml). Later, Sadiq et al.

(2011) tested alumina nanoparticles against algae Scenedesmus sp. and Chlorella sp.

A decrease in the chlorophyll content was also observed in the cells treated with

alumina nanoparticles.

Geoprincy et al. (2012) tested alumina nanoparticles against four major pathogenic

strains such as Bacillus cereus, Bacillus subtilis, Klebsiella pneumoniea and Vibrio

cholera. The alumina showed a characteristic inhbition zone of 12 mm diameter

against Bacillus subtilis and 23 mm diameter against Bacillus cereus of nanoparticles.

CuO nanoparticles were reported effective for killing a range of bacterial pathogens

involved in hospital-acquired infections. But a high concentration of CuO

nanoparticles achieves a bactericidal effect (Ren et al., 2009). Recently, Ahamed et

al. (2014) have investigated antimicrobial activity of CuO NPs against Escherichia

coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Enterococcus faecalis,

Shigella flexneri, Salmonella typhimurium, Proteus vulgaris and Staphylococcus

aureus. It has been observed that E. coli and E. faecalis exhibited the highest

sensitivity toword CuO NPs.

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School of Chemistry 41

Huang and co-workers (2012) demonstrated that Cu2O nanoparticles exhibited

excellent biocidal action against Staphylococcus aureus bacteria. Antifungal activities

of CuO nanoparticles were tested against Cryptococcus sp., Candida glabrata and

Candida albicans. The result showed significant growth inhibition in Cryptococcus

sp. (Beevi et al., 2009). Koper and coworker (2002) reported excellent activity of

MgO against Escherichia coli and Bacillus megaterium. Silicon dioxide nanoparticles

have been observed for the reduction of bacteria viability of Escherichia coli, Bacillus

subtilis and P. fluorescens after 24 hours (Jiang et al., 2009). The antimicrobial effect

of TiO2 against fungi and bacteria has been demonstrated by Chawengkijwanich and

Hayata, (2008).

Polyaniline/Pt-Pd nanocomposite was tested against Streptococcus sp, Staphylococcus

aureus, Escherichia coli and Klebsiella pneumoniea bacteria by Boomi et al., (2012).

Lin et al. (2005) reported antibacterial activity of Au/TiO2 nanocomposite against

Escherichia coli and Bacillus megaterium. Necula et al. (2009) found that porous

TiO2\Ag composite coating caused complete killing of methicillin-resistant

Staphylococcus aureus within 24 h in all culture conditions. Wu et al. (2010) has

reported that copper Cu-doped TiO2 nanoparticles exhibited greater antibacterial

activity against Mycobacterium smegmatis. Similarly, Kavitha et al. (2013) explored

TiO2 chitosan nanocomposites against Staphylococcus aureus, Escherichia coli,

Klebsiella pneumoniae and Bacillus subtilis strains.

ZnO/SnO2 was tested for antibacterial activity against Escherichia coli under UV

illumination. The bactericidal activity was evaluated by formation of colonies on the

nutrient agar plates (Talebian et al., 2011). Antibacterial activities of

GC/PEG/ZnO/Ag nanocomposite were tested by Liu et al. (2012 against the bacterial

species Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and

Bacillus subtilis.

Prabhakar et al. (2011) have studied the excellent antibacterial activity of silver-PANI

nanocomposite as compared to pristine Ag nanopowder. The silver nanoparticles

doped chitosan/polyvinylpyrrolidone composites were used against Staphylococcus

aureus and Escherichia coli (Wang et al., 2012). Polyaniline–metal nanocomposite

exhibited good antibacterial activity in both gram positive and gram negative bacteria

(Prabhakar et al., 2011). Polyaniline/Ag nanocomposite showed excellent

Chapter-2 Review of literature

School of Chemistry 42

antibacterial activity compared to pure Ag nano powder against gram positive bacteria

Bacillus subtilis (Tamboli et al., 2012). Maity et al. (2012) used agar diffusion

method for the investigation of antimicrobial activity of methylcellulose–silver

nanocomposite against Bacillus subtilis, Bacillus cereus, Pseudomonas aeruginosa,

Staphylococcus aureus and Escherichia coli.

2.3.3. Sensor

Number of studies has reported on sensing, detection of pollutants and microbial

detection using nanoparticles (Chen et. al., 2013). Wu et al. (2009) reported a highly-

sensitive biosensor for detection of DNA hybridization using Ag+ ions in the presence

of AuNPs by the biocatalytic reaction of alkaline phosphate. Silver NPs were used as

a potentiometric redox marker for the development of potentiometric glucose

biosensor.

2.3.4. Adsorption

Nanomaterials have been used for destruction, desorption or magnetically guided

separation and purification (Zargoosh et al., 2013). Metal based nanomaterials have

been explored for the removal of heavy metals such as arsenic, lead, mercury, copper,

cadmium, chromium, nickel etc. from water system (Daus et al., 2004).

Several metal oxide nanoparticles have been simultaneously used for the removal of

arsenic and organic contaminants (Hristovski et al., 2009). Different types of

magnetic nanoparticles like Fe3O4, Fe2O3 and MFe3O4 with different surface

modifications have been widely studied for the environmental remediation and

removal of heavy metals and aromatic amines from waste water (Feitoza et al., 2014).

Guo and Chen, 2009 prepared cellulose loaded with iron oxyhydroxide adsorbent for

the adsorption and removal of arsenate and arsenite from aqueous systems.

2.3.5. Drug Delivery

In therapeutics, quantum dots can be exploited for targeted and controlled drug

delivery. Gold NPs incorporated into polymeric nanoparticles or liposomes that

enhanced diagnostic applications, encapsulate drugs for therapy, imaging and

apoptotic response. AuNPs have the ability to prevent phosphorylation of the proteins

Chapter-2 Review of literature

School of Chemistry 43

involved in angiogenesis, by binding to the cysteine residues in heparin-binding

growth (Bhattacharya and Mukherjee et al., 2008). Gold NPs have been reported good

potential nanocarrier for drug delivery (Ghosh et al., 2009).

ZnO nanoparticles have been studied for targeted drug delivery, controlled drug

release and anticancer agent (Prasanth et al., 2013). Depan et al. (2004) have reported

chitosan-g-lactic acid and Na-MMT for controlled drug delivery and tissue

engineering applications. Cypes et al. (2003) fabricated drug-loaded poly (ethylene-

co-vinyl acetate) nanocomposites with organoclays to controlled drug release. Prucek

et al. (2011) observed cytotoxicity of Fe2O3/Ag nanocomposite against mice

embryonal fibroblasts. Chitosan–magnesium aluminum silicate films were prepared

for drug delivery application (Khunawattanakula et al., 2010). Resently, Justin,

(2014) found that chitosan–graphene oxide nanocomposites possess controlled drug

delivery application.

2.3.6. Food and Nutrition

Nanoparticles have been widely reported as analytic tools and biosensors for food

analysis, chemistry and food safety. ZnO nanoparticles have been utilized for

voltammetric determination of ascorbic acid and folic acid in the food (Vinayaka and

Thakur, 2010).

Au NPs labeled with streptavidin–horseradish peroxidase were used efficiently for the

determination of zearalenone (a mycotoxin produced in foods and feeds by some

fungi belonging to the genus Fusarium) using chemiluminescence immunoassay.

Recently, Au NPs have been widely employed for the determination of food

ingredients like folic acid, soy protein, antioxidants and food safety for the detection

and determination of toxins and pathogens (Mirmoghtadaie et al., 2013)

Magnetic nanoparticles have been widely reported for the separation,

preconcentration and detection of food pollutants like dyes, heavy metals, food toxins

(ochratoxin and aflatoxins) and pathogens (Escherichia coli, Cronobacter sakazakii,

Bacillus anthracis and Salmonella). The effect of ZnO-ZnS nanocrystals on the

binding affinities of different types of flavanoids with bovine serum albumin and their

potential use for food has been studied (Xiao et al., 2011).

Chapter-2 Review of literature

School of Chemistry 44

2.3.7. Agricultural

Nanomaterials based technologies have been developed and used for real time

monitoring and control the field, soil, crop and environment to optimize the resources

and maximize the crop production conditions. Nanomaterial are enables the early

detection and diagnosis of pests and plant disease management (Ghormade et al.,

2011). In the animal production and veterinary, the nanomaterial have been used in

different ways such as pathogen detection and removal, animal feeding, vaccination,

vaccine adjuvant, veterinary medicine as diagnosis, drug delivery, gene therapy and

tissue repairing.

2.3.8. Electronic

Multi-wall carbon nanotubes have been demonstrated in the supercapacitors for

energy storage, field emission devices for flat panel displays and nanometer-sized

transistors (Whatmore, 2006).

Ferroelectric oxides barium titanate (BaTiO3), lead zirconate titanate (Pb(Zr,Ti)O3)

and barium-strontium titanate (Ba,Sr)-TiO3 were used in transducers, actuators, and

high-k dielectrics (Matsui, 2005). Matsui (2005) noted that titanium dioxide and

cadmium selenide nanoparticles were used in photovoltaic devices.

Matsui (2005) have reported the zinc oxide nanoparticles for various optoelectronic

devices and galium nitride for LEDs. ZnO nanowires in LEDs developed large area

lighting on flexible substrates. IBM has developed complete electronic integrated

circuit around a single carbon nanotube molecule (IBM, 2006)

2.3.9. Cosmetics

Nanomaterials found many applications in cosmetic products including moisturizers,

hair care products, make up and sunscreen. Niosomes were developed and patented by

L‟Oreal in the 1970 and 80 The first product „Niosome‟ was introduced in 1987 by

Lancome using niosomes in cosmetic and skin care applications include their ability

to increase the stability of entrapped drugs, improved bioavailability of poorly

absorbed ingredients and enhanced skin penetration (L‟Oreal company) (1989 US

Patent 4830857, 1975, French Patent 2315991).

Chapter-2 Review of literature

School of Chemistry 45

The first products containing lipid nanoparticles appeared on the market in 2005,

offering increased skin penetration. L‟Oreal has a patent for a formulation containing

hyperbranched polymers or dendrimers used in wide variety of cosmetics e.g. mascara

or nail polish. Several patents have been filed for the application of dendrimers in

hair care, skin care and nail care products (L‟Oreal, US Patent 6287552, 2001). Zinc

oxide (ZnO) and titanium dioxide (TiO2) particles have been widely used for many

years as UV filters in sunscreens. ZnO or TiO2 are transparent and increased the

aesthetic appeal, are less smelly, less greasy and more absorbable by the skin. Many

sunscreens and moisturisers available, including products from Boots, Avon, Body

Shop, L‟Oreal and Nivea. Carnauba wax nanoparticles with TiO2 nanoparticles were

found to increase the sun protection factor (Villalobos et al., 2006).