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SYNTHESIS AND CHARACTERIZATIONS OF COPPER NANOPARTICLES MATERIAL

MINISTRY OF EDUCATION AND TRAINING

VIETNAM ACADEMY
SCIENCE AND TECHNOLOGY

GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY

CAO VAN DU

SYNTHESIS AND CHARACTERIZATIONS
OF COPPER NANOPARTICLES
MATERIAL
Specialization: inorganic chemistry
Code number: 62 44 01 13

DOCTORAL THESIS ABSTRACTS’ INORGANIC CHEMISTRY

Ho Chi Minh City – 2016


The work was completed at:

Laboratory nano Lac Hong University, Laboratory of nano University of Natural
Sciences, Institute for Materials Science Applications, Vietnam Academy of Science
and Technology

Scientific guidance:
1.

Assoc. Prof. Dr. Nguyen Thi Phuong Phong

2.

Dr. Nguyen Thi Kim Phuong

1st Peer Reviewer:
2nd Peer Reviewer:
3rd Peer Reviewer:

The theeesis dissertation will be defended in front of doctoral thesis judgement, held at
the Academy of Sciences Institute of Applied Materials, Graduate University of
Science and Technology , No. 1 , Mac Dinh Chi , District 1, HCMC city, Viet Nam.
At ......, ……………, 2016

Can learn dissertation at the library:
National Library of Vietnam,
Library of Vietnam Academy of Science and Technology


INTRODUCTION
In recent years, metal nanoparticles have attracted the attention of scientists due to their special
properties that differ distinctly from the corresponding bulk materials by surface area to volume ratio and
small size of them. The ability to synthesize metal nanoparticles with different shapes and sizes is
important to explore their applications in electronics, catalysis, sensors, optical and biological devices. As
most of these applications were governed by silver, gold and platinum. However, the high cost constraint
of these metals restricted their applications in high volume production. Presently, copper nanoparticles
provided a good alternative of silver, gold and platinum nanoparticles because of their lower cost and
catalytic activity, novel electronic, optical and magnetic properties or have antibacterial and antifungal
properties ... Compared to other metal nanoparticles materials, the synthesis of copper nanoparticles are
more difficult because of

surface easy oxidizing of copper.


Therefore, the synthesis of copper

nanoparticles with high purity would be a prerequisite for many application areas such as electricity electronics, optics, catalysis, chemistry, biology ...
Up to now, several methods have been developed for the preparation of copper nanoparticles, such
as electron irradiation, the plasma process, chemical reduction method, in situ methods, two-step
reduction method, thermal decomposition, electro-chemical reduction, reduction with ultrasound,
microwave heating, supercritical methods, ...
Methods for the preparation of copper nanoparticles often common aim is to create nanoparticles at
small sizes, high-stability for maximize applications. However, a large number of published on synthetic
of copper nanoparticles still has many disadvantages, such as long time or high temperatures to complete
the reaction, copper salts were chemically reduced in organic solvents under strict conditions, complex
equipment systems, using capping agents not guarantee for the stability of the copper nanoparticles
colloidal solutions. Moreover, in the most recent published works, one of the most important applications
of the copper nanoparticles was tested for antibacterial to treat and kill drug-resistant microorganisms.
The results showed that copper nanoparticles colloidal solutions shown bactericidal activity with various
gram (-), gram (+) cause disease in humans and animals. Antifungal activity has not been mentioned
much, only published work of Sahar M. Ouda (2014) showed results in resistance against two strains of
plant pathogenic fungi on Botrytis cinerea is Alternaria alternate and Botrytis cinerea.
On this basis, to overcome the disadvantages of synthetic copper nanoparticles with traditional
chemical reaction system. The content of the thesis is performed primarily with the synthesis of copper
nanoparticles from the basic reaction systems including precursor, protection and reducing agent. The
limitations of these reaction system will be improved by the synthesis of the new systems that is a
combination of two or three protections. The combination of protective substances include protection of
large molecular weight (PVA) and the protection of small molecular weight (trisodium citrate, ascorbic
acid, CTAB) will make new rules of the synergistic effect in order to control the size and ensure the

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stability of copper nanoparticles. The thesis also clarified the physicochemical and biological
characteristics of copper nanoparticles materials forming.
The main contents of the thesis:
- Synthesis of the copper nanoparticles colloidal solutions by chemical reduction method with various
precursors including copper oxalate, CuCl2, CuSO4, Cu(NO3)2 with hydrazine hydrate reducing agent,
NaBH4; solvent glycerin and water, PVA and PVP protection, dispersants and protective agents:
including trisodium citrate, ascorbic acid, CTAB.
- Investigating the influence of the parameters in the synthesis to the shape, size and distribution of
copper nanoparticles forming such as reaction temperature, concentration of reducing agent, the ratio of
precursors and capping agent, solution pH.
- Investigating the effect of the protective agent PVA, PVP, dispersants trisodium citrate, ascorbic
acid protect auxiliaries, CTAB surfactant to the size and distribution of copper nanoparticles forming.
- Investigating the specific physicochemical properties of copper nanoparticles forming by the
modern analytical methods such as UV-Vis spectrum, X-ray diffraction (XRD), transmission electron
microscopy (TEM).
- Investigating the antifungal activity and high killing ability against Corticium salmonicolor of the
copper nanoparticles colloidal solutions in the laboratory.
Meaning of science and practice of the thesis
The thesis provides the basis for the study a systematic process of synthetic copper nanoparticles
material overview domestic and foreign researches.
The results of the thesis will make clarify the rules of relationship between the size of copper
nanoparticles forming with their special characteristic is surface plasmon resonance via UV-Vis spectrum.
By using a various of precursors, reducing agents, protective agents, the synthesis was performed with the
survey parameters which control the size of copper nanoparticles forming, from that explore best
bioavailability of the copper nanoparticles colloidal solutions. This is also the scientific basis for
subsequent applied research.
The layout of the thesis:
The thesis has 128 pages with 8 tables, 108 figures. Besides the introduction (3 pages), conclusions
(2 pages), list of publications (2 pages) and references is updated to 2015 (9 pages), Annex (11 pages).
The thesis is divided into 3 chapters as follows:
Chapter 1 : Overview 28 pages
Chapter 2 : Experimental 10 pages
Chapter 3 : Results and discussions 74 Pages
New contributions of the thesis
1. The first time thesis presented a systematic synthesis of the copper nanoparticles colloidal
solutions base on chemical process with various precursors including copper oxalate, CuCl2, CuSO4,
2


Cu(NO3)2, various reducing agents: hydrazine hydrate, NaBH4; protective agents: PVA and PVP,
dispersant and protective agents: trisodium citrate, ascorbic acid, CTAB in 2 solvent: glycerin and water.
The novelty of the thesis was use glycerin solvent and protective agents (PVP, PVA, trisodium citrate) to
ensure the formation of colloidal solutions with high stability.
2. Rules, relationships between the size of copper nanoparticles with absorption peak shift through
surface plasmon resonance from UV-Vis analysis were characterised and clarified.
Characterization:
Using the chemical reduction method with reducing agent hydrazine hydrate, NaBH4 to synthesize
the copper nanoparticles colloidal solutions from precursors (copper nitrate, copper chloride, copper
sulfate). Using thermal reducing method with the used glycerol both solvent and reduction to synthesis
the copper nanoparticles colloidal solutions from copper oxalate precursors.
Using thermal analysis DTA-TG to determine temperature ranges that CuC2O4 changes volume,
creating the basis for the synthesis of copper nanoparticles from copper oxalate precursors.
Using UV-Vis to determine the optical properties, the shift plasmon absorption peaks of copper
nanoparticles. Predicting the size of copper nanoparticle forming.
Using X-ray diffraction (XRD) to determine the crystal structure, the purity of the copper
nanoparticles.
Using TEM to determine the morphology, size, combined with IT3 software to perform particle size
distribution of copper nanoparticles.
Using invitro testing method and spray directly method for testing antifungal activity and high
killing ability against C. salmonicolor.
3. RESULTS AND DISCUSSION
3.1 Synthesis of copper nanoparticles from copper oxalate precursors
3.1.2 Investigating the influence of the parameters on the size of copper nanoparticles
3.1.2.1 Effect of temperature
Figure 3.5 is the result UV-Vis spectrum of the copper nanoparticles colloidal solutions, the results
showed:
- Curve (a): UV-Vis spectrum of the mixture CuC2O4 dispersed in glycerin, only show an
absorbance peak at 305 nm wavelength; this is the absorbance peak of the copper oxalate.
- Curve (b): UV-Vis spectrum of the samples was prepared at reaction temperature of 220 oC,
reaction time was 2 minutes. The results show that besides the absorbance peak at 305 nm wavelength,
There is an absorbance peak appears at wavelength 580 nm. This is the absorbance peak of copper
nanoparticles, this phenomenon was result of the surface plasmon resonance that occurs with copper
nanoparticles. This result indicates that the reaction had occurred to form copper nanoparticles, but the
reaction did not occur completely, therefor still has copper oxalate in solution. This result compare with
the result of the thermal analysis DTA - TG Figure 3.4 could conclude that the reaction did not occur by
the thermal decomposition mechanism, because the reaction of thermal decomposition copper oxalate
3


only occurs at temperatures of 270 °C. Thus, with the result obtained, it can be concluded that the
reaction formed copper nanopaticles occurs in both thermal reduction and chemical reduction mechanism
with glycerin acts as both solvent and reduction.
- Curve (c): Samples were prepared at temperature of 230 oC, UV-Vis results showed that there was
only the absorbance peak at 584 nm wavelength; do not appears absorbance peak of copper oxalate. Thus,
the reduction of copper oxalate has occurred almost completely.

Figure 3.5: UV-Vis spectra of (a) copper
oxalate, (b) CuNPs + copper oxalate (220

°C, (c) and CuNPs (230 oC)

Figure 3.6: TEM and particle size
distribution of CuPNs were
synthesized at 230 oC)

Figure 3.6: TEM and particle size
distribution of CuPNs were
synthesized at 240 oC)

Copper nanoparticles were synthesized at 240 °C with unchanged reaction conditions. Figure 3.6
and 3.7 are TEM images and particle size distributions of copper nanoparticles were synthesized at
temperature of 230 °C and 240 °C. At temperatures of 230 °C, the copper nanoparticles were created in
spherical, had average diameter in range of 12 ± 3.6 nm (Figure 3.6). At temperature of 240 °C, copper
nanoparticles have spherical with the average size in range of 29.6 ± 4.2 nm (Figure 3.7).
3.1.2.2 Effect of ratio CuC2O4/PVP
Table 3.1: Data and results of the copper nanoparticles were synthesized via ratio CuC2O4/PVP
Samples

ratio (%)
CuC2O4/PVP

PVP
(g)

K1

1

0.002

580

5.5 ± 2.3

K2

3

0.006

585



K3

5

0.010

592

36 ± 5

K4

7

598



K5

9

0.018

600

68 ± 6.3

K6

11

0.022

614



K7

15

0.030

623



0.2

CuC2O4 (g)

0.014

Temperature Absorbance Average size via
(oC)
peak (nm)
TEM (nm)

230

Table 3.1 shows summarily UV-Vis and TEM results of the copper nanoparticles colloidal
solutions. The results showed that all samples had phenomenon of surface plasmon resonance which
occurs with copper nanoparticles at the position of maximum absorbance peaks were K1 (580 nm), K2
4


(585 nm ), K3 (592 nm), K4 (598 nm), K5 (600 nm), K6 (614nm), K7 (623 nm) corresponding to ratio
CuC2O4 / PVP is 1, 3, 5, 7, 9, 11 , 15%, respectively.
The absorbance peaks of the copper nanoparticles colloidal solutions shift to larger wavelengths
(redshift) from 580 to 623 nm, while the intensity of the absorance peaks also increased. According to
Mie theory, it could be predicted that the size of copper nanoparticles increase when the ratio
CuC2O4/PVP increases from 1 to 15 %.
The results of TEM images in Figure 3.11 to Figure 3.13 show that, at concentration 1 % of CuC2O4
compared to PVP, copper nanoparticles were created mostly in spherical and distributed with the average
size was 5.5 ± 2.3 nm (Figure 3.11). When concentration of CuC2O4 increase to 5 % (Figure 3.12) and 9
% (Figure 3.13) compared to PVP, copper nanoparticles forming were distributed in a wide range and
agglomerated, with the average size 36 ± 5 nm and 68 ± 6.3 nm, respectively. These results were
consistent entirely compared to the shift position of maximum absorance peaks of copper nanoparticles in
the UV-Vis spectrum from 580 to 600 nm.

Figure 3.11: TEM image and particle
size distribution of CuNPs were
synthesized in the weight ratio
CuC2O4 /PVP = 1 %

Figure 3.12: TEM image and
particle size distribution of CuNPs
were synthesized in the weight
ratio CuC2O4 /PVP = 5 %

Figure 3.13: TEM image and particle
size distribution of CuNPs were
synthesized in the weight ratio
CuC2O4 /PVP = 9 %

3.1.2.3 Effect of pH
Initial solution has neutral pH values, to investigate the influence of solution pH to the formation of
copper nanoparticles colloidal solutions, the reaction solution was controlled pH by NaOH 0.1 M. All
samples were prepared with the same condition such as CuC2O4/PVP = 5 %, the reaction time was 2
minutes. Preliminary experiments showed that when the solution pH of the mixture increases, the reaction
to form copper nanoparticles occurs at lower temperatures (140 °C).
Observe the change of color in the solution pH adjustment process as well as the actual reaction
occured, the synthesis mechanism was changed and can be explained as follows: when adding NaOH to
the mixture along with mixing, the mixture of copper oxalate in glycerol changed the color from light
blue to dark blue, this could be the formation of complex [Cu(OH)4]2+, this complex could be bonded
with PVP at the position of nitrogen and oxygen in a chain of molecule PVP. Thus, potential redox
(ECu2+/Cu) changed and made the ΔG value of reaction was more negative, therefor the temperature of the
reaction in the case of high solution pH ( 8) will be lower (140 °C) compared to the reaction occurs at
neutral solution pH (230 oC).
5


Table 3.2: Data and results of the copper nanoparticles were synthesized via solution pH
Samples

pH
Ratio (%)
Temperature Absorbance
Value CuC2O4/PVP
(oC )
peak (nm)

K3

7

D1
D2
D3
D4

8
9
10
11

D5

12

230
5
140

Average size
via TEM (nm)

Particle shape

592

36 ± 5

spherical

596
600
601
601


77 ± 5.3
82 ± 4.2


spherical, polygon
spherical, polygon

600

96 ± 5.6

spherical, cubic,
triangle, rod

The results were summarized in Table 3.2 shows that, when the pH value increases in 8 ÷ 12, the
copper nanoparticles had phenomenon of surface plasmon resonance corresponding to maximum
absorbance peaks at wavelengths 596; 600; 601; 601; 600 nm, respectively. TEM images showed that,
when the solution pH increases, the size of copper nanoparticles forming also increases. Specific, the
average size of the copper nanoparticles at pH = 9, pH = 10, pH = 12 in range of 77 ± 5.3 nm (Figure
3.16), 82 nm ± 4.2 (Figure 3.17), 96 ± 5.6 nm (Figure 3.18), respectively. In particular, copper
nanoparticles were formed not only spherical but also cubic, triangle, rod, polygon.

Figure 3.16: TEM image and particle
size distribution of CuNPs were
synthesized at solution pH = 9

Figure 3.17: TEM image and particle
size distribution of CuNPs were
synthesized at solution pH = 10

Figure 3.18: TEM image and particle
size distribution of CuNPs were
synthesized at solution pH = 12

3.2 Synthesis of copper nanoparticles from copper salt precursors
3.2.1 Synthesis of copper nanoparticles from copper nitrate precursors
3.2.1.1 Effect of the concentration of reducing agent
Figure 3.22 to Figure 3.24 were TEM images and the particles size distribution of copper
nanoparticles were synthesized at different concentrations of reducing agent. Figure 3.22 shows that, at
HH concentration 0.1 M, the copper nanoparticles forming had smallest average size (14 ± 9 nm).
However, the particle size distribution was created in the wide range from 6 ÷ 47 nm, mostly in spherical
and combined of smaller particle size. When increases HH concentrations from 0.2 to 0.5 M, the copper
nanoparticles were created in spherical and monodisperse with average size 25 ± 5 nm (Figure 3.23) and
67 ± 9 nm (Figure 3.24) respectively.

6


Figure 3.22: TEM image and particle
size distribution of CuNPs were
synthesized at HH concentration 0.1 M

Figure 3.23: TEM image and particle
size distribution of CuNPs were
synthesized at HH concentration 0.2 M

Figure 3.24: TEM image and particle
size distribution of CuNPs were
synthesized at HH concentration 0.5 M

3.2.1.2 Effect of temperature

Figure 3.27: TEM image and particle
size distribution of CuNPs were
synthesized at 110 oC

Figure 3.28: TEM image and particle
size distribution of CuNPs were
synthesized at 130 oC

Figure 3.29: TEM image and particle
size distribution of CuNPs were
synthesized at 150 oC

Figure 3.27 to 3.29 were TEM images and particle size distribution of the copper nanoparticles
were synthesized at different temperatures. At temperatures of 110 °C (Figure 3.27), the copper
nanoparticles were created in spherical, monodisperse with average size of 17 ± 4 nm. As the
temperatures were higher, at 130 °C (Figure 3.28) and 150 °C (Figure 3.29) the copper nanoparticles
forming had larger size, in a wide range with the average size 33 ± 5 nm and 50 ± 20 nm respectively.
3.2.1.3 Effect of ratio Cu(NO3)2/PVP

Figure 3.32: TEM image and particle
size distribution of CuNPs were
synthesized with ratio of Cu(NO3)2/PVP
=1%

Figure 3.33: TEM image and particle
size distribution of CuNPs were
synthesized with ratio of Cu(NO3)2/PVP
=3%

7

Figure 3.33: TEM image and particle
size distribution of CuNPs were
synthesized with ratio of Cu(NO3)2/PVP
=7%


The results of TEM images from Figure 3:32 to 3:34 shows, as ratio of Cu(NO3)2/PVP was 1 %, the
copper nanoparticles were formed mainly in spherical, monodisperse in range of 5 ± 3 nm (Figure 3.32).
When the ratio of Cu(NO3)2/PVP increased to 3% and 7%, the copper nanoparticles were formed still in
spherical and had diameter with average size of 15 ± 5 nm (Figure 3:33) and 22 ± 5 nm (Figure 3:34)
respectively, the copper nanoparticles were agglomerated.
 Summary and general discussion about the results of copper nanoparticles were synthesized
from copper oxalate and copper nitrate precursors when using only PVP as protective agent:
Table 3.4: Summary the results of copper nanoparticles were synthesized from copper oxalate and copper
nitrate precursors
Precursors/
synthetic
conditions
Agents

Synthetic
conditions

Results of UVVis (nm)
The best
synthesis
conditions

copper oxalate
Copper
oxalate

Glycerol

PVP
1.000.000 g/mol

Copper
nitrate

Glycerol

Temp
(oC)

Concentra
tions of
reducing
agents

Ratio Copper
oxalate/ PVP

Temp
(oC)

Concentrations
of reducing
agents HH (M)



1 ÷ 15%



580 ÷ 600

210 ÷
240
580 ÷
584
Temp
230 oC

Results of
TEM

Copper nitrate

Concentra
tions of
reducing
agents


110 ÷
160
573 ÷
602

01 ÷ 0,5

1 ÷ 9%

580 ÷ 590

568 ÷ 600

Ratio Copper
oxalate/ PVP

Temp

Concentrations
of reducing
agents

1%

110

0,2 M

5,5 ± 2,3 nm

Hydrazine
hydrate
Ratio
Copper
nitrate/
PVP

Ratio
Copper
nitrate/
PVP
1%

5 ± 3 nm

Table 3.4 are the results of copper nanoparticles which were synthesized by using PVP as a
protective agent. The results could be more explained as follows:
- The size of copper nanoparticles forming are difficult to control through the survey parameters.
Specifically, position of the plasmon absorbance peaks shifted in large range of wavelengths when the
temperature, concentration of reducing agent, ratio of precursor/protective agent were changed. These
could be predicted that the size of nanoparticle were changed and distributed in the wide range of sizes.
Through TEM images analysis, the prediction was confirmed and clarified.
- At the best conditions, copper nanosparticles formming had the smallest average size (2.3 ± 5.5
nm from copper oxalate precursor and 5 ± 3 nm from copper nitrate precursor). However, these results
were achieved by using with small amount of precursor (ratio precursor/protectant = 1 %), corresponding
to low concentration of copper nanoparticles were obtained in this procedure.
Thus, it can be concluded that the copper nanoparticles were produced by using PVP (Mw:
1,000,000 g/mol) as a protective agent. The steric stabilisation of copper nanoparticles were achieved in
this procedure. However, because of the large size of polymer molecules so it is difficult to coat all
8


surfaces of the copper nanoparticles in order to protect them from their collision as the large amount of
copper nanoparticles were formed. Therefore, to control the copper nanoparticles in smaller size, with
larger concentration then protective agents must have the ability of electrostatic stabilisation and steric
stabilization simultaneously. To solve this problem, in the next content of the thesis, copper nanoparticles
were produced by using trisodium citrate as second protective agents.
With the results of the thesis has presented, the rules of the change size of copper nanoparticles
according to the survey have been published with two articles in the Journal of Science and
Technology 52 (1C), 2014. The rule of the change size with temperature, the result of XRD analysis
were discussed in the article "Synergistic effect of citrate dispersant polymers on controlling size and
capping growth of ultrafine copper nanoparticles" in the journal international Journal of
Experimental Nanoscience, Vol. 10, No. 8, 2015 (IF: 0981).
3.2.1.4. Investigating the synthesis of copper nanoparticles in the present of trisodium citrate
a. Effect of the amount of trisodium citrate

Figure 3.37: UV-Vis spectra of copper
nanoparticles were synthesized by
amount of trisodium citrate

Figure 3.38: TEM image and
particle size distribution of CuNPs
were synthesized by ratio of
trisodium/Cu(NO3)2 = 0,5

Figure 3.39: TEM image and
particle size distribution of CuNPs
were synthesized by ratio of
trisodium/Cu(NO3)2 = 1,0

Figure 3.37 is UV-Vis spectra of copper nanoparticles were synthesized by amount of trisodium
citrate. The results showed that the position of the peak absorption were shifted by using trisodium citrate
dispersant. Specifically, UV–Vis absorbance of copper colloidal solution were prepared without trisodium
citrate had absorbance peak at 584 nm wavelength (the curve M3), samples have trisodium citrate with
low concentrations (trisodium citrate/Cu(NO3)2 = 0.1; 0.25) in which the UV–Vis absorbance of copper
colloidal solution had absorption peaks at a wavelength of 574 and 568 nm respectively (the curve M2,
M1). The samples (trisodium citrate/Cu(NO3)2 = 0.5; 0.75; 1.0; 1.25 ; 1.5) had the absorption peaks in the
wavelength range from 562 to 563 nm. Thus, it can be concluded that the size of copper nanoparticles
were prepared in the presence of trisodium citrate smaller than copper nanoparticles were prepared
without trisodium citrate. The size of copper nanoparticles had stable and the smallest size which were
synthesized by using ratio of trisodium citrate/Cu(NO3)2 ≥ 0.5.
Figure 3.38 and 3.39 are TEM images of the copper nanoparticles colloidal solution were prepared
by using ratio of trisodium citrate/Cu(NO3)2 = 0.5 and 1.0. The results showed that copper nano particles

9


generated mainly in the spherical, with narrow distribution, the average size of copper nanoparticles are 4
± 2 and 3 ± 2 nm respectively.
b. Effect of ratio Cu(NO3)2/PVP in the presence of trisodium citrate

Figure 3.41: UV–Vis spectra of copper
nanoparticles were synthesized by using
ratio of Cu(NO3)2/PVP from 1 to 15 %

Figure 3.42: TEM image and particle
size distribution of CuNPs were
synthesized by using ratio of
Cu(NO3)2/PVP = 5 %

Figure 3.43: TEM image and particle
size distribution of CuNPs were
synthesized by using ratio of
Cu(NO3)2/PVP = 9 %

The copper nanoparticles colloidal solution were synthesized in the presence of trisodium citrate,
the results of the UV-Vis analysis were shown in figure 3.41. The results shown that, the increase in the
ratio of Cu(NO3)2/PVP, the intensity of absorbance peak also increased. However, the shift of the
maximum absorbance peak changed in narrow wavelength. Specifically, when the ratio of Cu(NO3)2/PVP
increased

from

1

to

13

%,

the

position

of

the

maximum

absorbance

peak

was

displayed at the wavelength from 562 to 564 nm. As the ratio of Cu(NO3)2/ PVP increased to 14 and 15
%, the position of maximum absorbance peak shifted to longer wavelengths (two the tallest peaks) at 566
and 568 nm respectively. These signals indicated that the larger of the particles were prepared by using
the ratio of Cu(NO3)2/PVP greater than 13 %.
Figure 3.42, 3.38 and 3.43 are TEM images of copper nanoparticles colloidal solutions which were
prepared by using the ratio of Cu(NO3)2/PVP = 5 %, 7 % and 9 % in the presence of trisodium citrate.
The results shown that, with the ratio of Cu(NO3)2/PVP = 5 %, the copper nanoparticles were generated
mainly in the spherical, with narrow distribution, its diameter appears in a range of the average size of 4 ±
1 nm (Figure 3.42). Copper nanoparticles were created with similar results by using the ratio of
Cu(NO3)2/PVP = 7 % and 9 %, its diameter appears in a range of the average size of 4 ± 2 nm (Figure
3.38 ) and 3 ± 2 nm (Figure 3.43) respectively. These results fited perfectly with the results of UV-Vis
analysis in Figure 3.41. This study will be the basis for the syntheis of copper nanoparticles with narrow
distribution, small size and high performance.
3.2.2 Synthesis of copper nanoparticles from copper cloride precursors
3.2.2.1 The basis on the synthesis of copper nanoparticles from copper chloride precursors
Based on the results from the synthesis of copper nanoparticles from copper nitrate salt, this study
will focus on the synthesis of copper nanopaticles colloidal solution from copper chloride sprecursor. The
process was performed according to the synthesis of copper nitrate precursor, the parameters of the
investigating will be prepared with the reaction agents including copper chloride precursor, hydrazine
10


hydrate reducing agent, protective agent PVP (MW = 58,000 g/mol), solvent glycerol, trisodium citrate
dispersant agent. The best parameters were used to synthesize copper nanoparticles colloidal solution by
using PVA (Mw = 60,000 g/mol) as protective agent. The results from these investigating will be collated
with the result of the synthesis copper nanoparticles from copper nitrate precursors. From that, the rules
of the synergistic effect of large molecular weights (PVP, PVA) and small molecular weight (trisodium
citrate) will be made clearly, the best system protection for the synthesis of copper nanoparticles from this
conclution will be clarified.
3.2.2.2 investigating of parameters on the size of copper nanoparticles
According to the results of Xiao-Feng Tang [13], Mustafa BICER [16], Mohammad Vaseem [18],
ZHANG Qiu-li [21] as they synthesized copper nanoparticles by chemical reduction method with the
different of reaction agents (table 1.1) or in the study with copper xalate and copper nitrate precursors of
the thesis. The parameters such as temperature or concentration of the reducing agent has strong influence
on the size and distribution of the copper nanoparticles forming. However, the relationship between the
size, the distribution of particles with the parameters of the synthesis in various reaction systems still
need to clarify. In this study, the effect of various parameters on the size and distribution of copper
nanoparticles will be clarified when the protective polymer (PVP, PVA) and trisodium citrate were used
together.
a. Effect of temperature

Figure 3.45: UV–Vis spectra of copper
nanoparticles were synthesized from copper
chloride at diffirent temp from 100 to 160 oC

Hình 3.47: UV–Vis spectra of copper nanoparticles were
synthesized with various of reducing agent concentration
hydrazinezin hydrate from 0,1 to 0,7M.

Figure 3:45 is UV-Vis spectra of copper nanoparticles colloidal solution which were synthesized at
different temperatures. The results shown that, when the temperature increased from 100 to 160 °C, the
position of the maximum absorbance peak unchanged or changed very little. The absorbance peak
appeared at the wavelength from 562 to 564 nm. These results predicted that the size of copper
nanoparticles forming changed a little when temperature were controlled from 100 to 160 °C. In addition,
in the range of wavelength 400 ÷ 500 nm does not appear strange peaks, which may be concluded that the
copper nanoparticles were created by protected surface, not oxidized, the product has high purity and do
not has Cu2O. On other hand, compared to the the results of the investigating according to the temperature
from copper nitrate. It could be confirmed the role of trisodium citrate as dispersant agent to controll the
11


size of copper nanoparticles forming: when trisodium citrate was used with appropriate content, the
copper nanoparticles were synthesized with small size and uniformity in the range of temperature 100 ÷
160 oC or larger.
b. Effect of the concentration of reducing agent

Figure 3.48: TEM image and
particle size distribution of CuNPs
were
synthesized
at
HH
concentration 0.2 M

Figure 3.49: TEM image and
particle size distribution of
CuNPs were synthesized at HH
concentration 0.5 M

Figure 3.50: TEM image and
particle size distribution of CuNPs
were
synthesized
at
HH
concentration 0.7 M

Figure 3.47 is UV-Vis spectra of copper nanoparticles colloidal solution which were synthesized at
diffirent concentration of reducing agent. The results shown that, the position of the maximum
absorbance peak was shifted to longer wavelengths when the concentration of reducing agent increased
from 0.1 to 0.7 M. Specifically, the position of the absorbance peaks are 562 nm (0.1 M; 0.2 M; 0.3 M);
563 nm (0.4 M); 567 nm (0.5 M); 572 nm (0.6 M); 580 nm (0.7 M) respectively. This result could be
predicted that the copper nanoparticles with small size and hight stable were prepared by using the
concentrations of reductant from 0.1 to 0.4 M. When the concentration of reducing agent increased from
0.5 to 0.7 M, the reaction happen faster, the formation of nucleation was greater in the short time. There
for, the protective agent trisodium citrate and PVP could not cover the surface of copper nanoparticles.
Thus, the aggregation of nanoparticles occurred to perform larger size.
Figure 3.48, 3.49, 3.50 are TEM images and size distribution of copper nanoparticles that were
synthesized at different concentration of reducing agent. The results shown that, at concentration of
reducing agent HH 0.2 M, the copper nanoparticles were prepared mostly in spherical, uniform
distribution in PVP with average size of 4 ± 2 nm (Figure 3.48). When concentrations of reducing agent
increased to 0.5 and 0.7 M, the copper nanoparticles forming has large size with the average diameter in
range of 15 ± 5 nm (Figure 3.49) and 22 ± 6 nm (Figure 3.50) respectively.
a. Effect of the amount of trisodium citrate
Figure 3.53 to 3.55 are the result of TEM images that shown the effect of the amount of trisodium
citrate to the synthesis of copper nanoparticles. The results shown that, the copper nanoparticles were
created with average diameter in range of 20 ± 7 nm when the sample were prepared without trisodium
citrate (Figure 3.53). However, the particles still tend to form larger particles and on the surface of larger
particles has the agglomeration of smaller particle. Synthetic form trisodium citrate from rate / CuCl2 =
12


0.1 and 0.5, the nano copper particles formed have a smaller average size, with corresponding values of
17 ± 5 nm (Figure 3:54) and 3 ± 1 nm (Figure 3:55).

Figure 3.53: TEM image and particle
size distribution of CuNPs were
synthesized
with
ratio
trinatri
citrat/CuCl2 = 0,10

Figure 3.54: TEM image and particle
size distribution of CuNPs were
synthesized with ratio trinatri
citrat/CuCl2 = 0,10

Figure 3.55: TEM image and particle
size distribution of CuNPs were
synthesized
with
ratio
trinatri
citrat/CuCl2 = 0,50

d. Effect of the ratio of CuCl2/ PVP in the presence of trisodium citrate
UV-Vis spectrum of the copper nanopaticles colloidal solution is presented in Figure 3.58. The
results shown that, when the ratio of CuCl2/ PVP increased (from 1 to 5%), the intensity of absorbance
peak increased. However, the change of position of the absorption peak shifted only from 562 to 564 nm.
As the ratio of CuCl2/ PVP increased to 6 and 7%, the position of surface plasmon absorbance peak were
567 and 572 nm respectively. Thus, it can be predicted that the copper nanoparticles were prepared in
small size when ratio of CuCl2/ PVP changed from 1 to 5 %,. However, the copper nanoparticles forming
increased when the ratio of CuCl2/ PVP increased to 6 and 7 %,. These results will be verified by TEM
images.

Figure 3.58: UV-Vis spectra of copper nanopaticles
were synthesized with the ratio of CuCl2/ PVP from
1 to 7 %

Figure 3.59: TEM image and particle size
distribution of CuNPs were synthesized
with ratio CuCl2/PVP = 5 %

Figure 3.55 and 3.59 are TEM images of the copper nanopaticles were synthesized by using the
ratio of CuCl2/ PVP 3 and 5 %. The results shown that, copper nanoparticles forming had uniform
distribution in spherical with average size 3 ± 1 nm and 4 ± 1 nm respectively. This result was consistent
with the absorption peaks from the effects of surface plasmon resonance of copper nanoparticles in small
size as shown in the UV-Vis spectrum in Figure 3:58.
13


e. Investigating of the synthesis of copper nanoparticles in the presence of trisodium citrate in
PVA capping agent
The best parameters for the synthesis of copper nanoparticles with protective agent PVP were used to
synthesis of copper nanopaticles with protective agent PVA (Mw = 60,000 g/ mol) as follows: PVA 0,2 g;
temperature at 110 °C, the concentration of HH 0.2 M; trisodium citrate was determined to ensure ratio of
trisodium citrate/ CuCl2 = 0.5. CuCl2 was determined to ensure ratio of CuCl2/ PVA = 5, 7%.

Figure 3.61: UV-Vis spectra of copper
nanopaticles were synthesized with
ratio of CuCl2/PVA = 5 % (curve 1)
and 7 % (curve 2)

Figure 3.62: TEM image and
particle size distribution of CuNPs
were
synthesized
with
ratio
CuCl2/PVA = 5 %

Figure 3.63: TEM image and particle
size distribution of CuNPs were
synthesized with ratio CuCl2/PVA =
7%

Figure 3.61 was UV-Vis spectrum of the copper nanopaticles which were synthesized by using
CuCl2/PVA = 5%, 7%. The results shown that, copper nanoparticles had surface plasmon absorbance
peaks at short wavelength. Specially, the absorbance peak appeared at 558 nm wavelength with ratio of
CuCl2/ PVA = 5 %. The absorbance peak shifted to longer wavelength at 562 nm with ratio of CuCl2/
PVA = 7%. Thus, the effect of surface plasmon resonance allows predicted that copper nanoparticles
were created in ultra-sized (<4 nm). The result of TEM images showed that copper nanoparticles created
with high distribution, the average size of 2 ± 1 nm (Figure 3.62) and 3 ± 1 nm (Figure 3.63) with ratio of
CuCl2/ PVA 5 % and 7 % respectively.
Thus, in the same conditions, copper nanoparticles were prepared by using PVA as protective agent
are smaller by using PVP. These result could be explained on the basis of the PVA and PVP protection
against nanoparticles. PVA and PVP are the polarization polymer that contain hydroxyl and amide
groups. These groups could be complexed with transition metals. The chain of PVA and PVP can cover
the surface of the particles to avoid agglomeration. However, PVA has hydroxyl groups in the density of
molecules is higher than the amide groups in the molecule PVP; this characteristic makes the viscosity of
PVA solution higher than in the same solution of PVP. This reduced the growth and aggregation of
copper nanoparticles forming. So, copper nanoparticles were prepared in PVA with uniform and smaller
size.
 Summary and general discussion on the results of the synthetic copper nanopaticles from copper
nitrate and copper chloride precursor with the use PVP, PVA and trisodium citrate as capping agent.
Table 3.6: Summary of the results of the synthesis copper nanoparticles from copper nitrate and copper
chloride precursors in the system of two capping agent
14


Precursor /
synthetic
Conditions
System of
reaction

Copper nitrate

The best
synthesis
conditions

- Trisodium citrat
- Glycerol
- PVP (58.000 g/mol)
- PVA (60.000 g/mol)
- Hydrazin.

- Trisodium citrat
- Glycerol
- PVP (1.000.000 g/mol)
- Hydrazin.

Temp
(oC),
Concentr
paremeters of ation of
investigating reducing
agent HH

Result of
UV-Vis (nm)

Copper cloride

Ratio of
trisodium
citrate/
copper
nitrate

Ratio of
copper
nitrate/ PVP



0 ÷ 1.5

1 ÷ 15 %



584 ÷ 562

562 ÷ 568

Temp
(oC),
Concentr
ation of
reducing
agent (M)

trisodium
citrate/
copper
nitrate

Ratio of
copper
nitrate/
PVP

110; 0.2

 0,5

1 ÷ 13 %

Result of
TEM

Concentr
ation of
reducing
agent
HH (M)

Ratio of
trisodium
citrate/
copper
cloride

Ratio of
copper
cloride/
PVP

01 ÷ 0.7

0 ÷ 1.25

1÷7%

562 ÷
580

580 ÷ 562

562 ÷ 572

Temp
(oC)

Concentr
ation of
reducing
agent
(M)

Ratio of
trisodium
citrate/
copper
cloride

Ratio of
copper
cloride/
PVP

110 ÷
160

0,1÷ 0,4

 0,5

1÷5%

Temp
(oC)

100 ÷
160
562 ÷
564

3 ± 1 nm in PVP
2 ± 1 nm in PVA

3 ± 2 nm

The results in Table 3.6 can give some discussions on the synthesis of copper nanopaticles in two
protective agent as follows:
- The size of the copper nanoparticles were prepared with small size, hight stability in the wide
range of synthesis parameters such as temperature, concentrations of reducing agent. This result was
achieved due to the synergistic protection of PVP and trisodium citrate.
- The results from the synthesis by using copper nitrate and copper chloride precursor are
equivalent when the synthesis was done by the same synthesis parameters. These results could be
concluded that copper nanoparticles were synthesized with equivalent size when using different copper
salt precursors.
- With the same synthesis parameters (temperature, concentrations of reducing agents, dispersant/
precursors), but with the use of protective PVP in different molecular weight (1.000.000 g/ mol; 58.000 g/
mol, for Cu(NO3)2 and CuCl2 respectively), the copper nanoparticles were created with similar size, in
range of 3 ± 2 nm and 3 ± 1 nm. However, there are differences in the concentration of copper
nanoparticles forming. Specifically, when using PVP (1,000,000 g/ mol), the copper nanoparticles were
created with stable size when ratio of Cu(NO3)2/PVP increased from 1 to 13 %. With the use PVP (58,000
g/mol), the ratio of CuCl2/PVP was from 1 to 5 %. These results can be explained that, as PVP was

15


created in solution with glycerin, by the molecular chain lengths increase (1.000.000 g/ mol compared to
58,000 g/ mol) that created better space effect when synergistic with trisodium citrate protection.
With the results was performed, the results of the thesis clarified the rules of the change size of
copper nanoparticles forming by using the experimental parameters such as temperature, concentration of
reducing agent, the rate of trisodium citrate/precursor, ratio precursor/protection through the phenomenon
of surface plasmon resonance of the nanopaticles by UV-Vis spectra combined to TEM images. These
result and rules have been recorded and published in two papers presented by the Journal of Chemistry,
Vol 51 (2C), 2013; international articles in the Journal of Experimental Nanoscience, Vol. 10, No. 8,
2015. The copper nanopaticles in PVA was tested Corticium samonicolor, the results was published in the
journal Bulletin of the Korean Chemical Society, Vol. 35, No. 9, 2014.
3.2.3 The results of the synthesis copper nanopaticles from copper sulfate precursors
The synthesis of copper nanopaticles from copper sulfate precursors will be done to clarify:
- Reaction system using water solvent, reducing agent NaBH4. These are all factors unfavorable for
the synthesis of copper nanopaticles. Water solvent has lower viscosity compare to glycerin, which
reduces the reliability of the adhesive system. NaBH4 reductant for the byproducts of hydrogen reduction
reaction is not effective antioxidant copper surface as is the case for the hydrazine reducing agent is
nitrogen gas byproducts. Therefore, in co-generation nano fusion will be present ascorbic acid as
antioxidant agent surface copper nano particles are formed.
- To copper nanoparticles were protected by good spatial effects, the content of the synthesis copper
nanopaticles from copper sulphate will use a combination of two protective agent PVP (Mw: 40.000
g/mol) and CTAB. These protective agent andr ascorbic acid will create the synergy of the three physical
protection for copper nanoparticles forming. This is the content of research that not many reports had
mentioned.
3.2.3.2 Investigating of the factors affecting to the copper nanoparticle size
a. Influence of the concentration of reducing agent

Figure 3.65: UV-Vis spectra of copper
nanopaticles were synthesized with
concentration of NaBH4 from 0,1 to
0,5M

Figure 3.66: TEM image and
particle size distribution of CuNPs
were
synthesized
with
concentration of NaBH4 0,3 M

16

Figure 3.67: TEM image and particle
size distribution of CuNPs were
synthesized with concentration of
NaBH4 0,5 M


Figure 3.65 is the UV-Vis spectra of the copper nanopaticles which was synthesized according to
the concentration of the reducing agent. The results shown that, when increasing the concentration of
reducing agent, the plasmon absorbance peaks of copper nanoparticles shifted to smaller wavelengths
from 582 nm (0.1 M) to 574 nm (0.2 M) and 570 nm (0.3 M). However, when the reducing agent
concentration was too high (0.4 m; 0.5 m), the position of the maximum absorption peak shifted to larger
wavelengths 574 nm and 578 nm respectively . The results shown that the best concentrations of reducing
agents to synthesis copper nanoparticle was 0.3 M.
Figure 3.66 and 3.67 are TEM images and size distribution of copper nanoparticles which were
synthesized with different concentrations of reducing agents. Results shown that, with the concentration
of NaBH4 0.3 M; copper nanoparticles were prepared with uniform distribution, mostly in spherical in the
average size of 20 ± 6 nm (Figure 3.66). As concentration of 0.5 M NaBH4; nanoparticles were created
mostly in spherical, uniform distribution, but the size was larger 39 ± 13 nm (Figure 3.67).
b. Effect of temperature

Hình 3.70: TEM image and particle
size distribution of CuNPs were
synthesized at 30 oC

Figure 3.71: TEM image and particle
size distribution of CuNPs were
synthesized at 50 oC

Figure 3.72: TEM image and particle
size distribution of CuNPs were
synthesized at 70 oC

Figure 3.70, 3.71, 3.72 are TEM images and size distribution of copper nanoparticles which were
synthesized with different temperatures. The results shown that, at 30 °C the copper nanoparticles were
generated in wide range, with the average size of 36 ± 16 nm (Figure 3.70), in addition to spherical also
have diffirent shape that has small particles on the surface of larger particles. When the temperature
increased to 50 oC and 70 °C, the copper nanoparticles were created mainly in spherical, the average size
was 21 ± 6 nm (Figure 3.71) and 33 ± 11 nm (Figure 3.72) respectively.
c. Effect of ratio of acid ascorbic/Cu2+
Figure 3.74 is UV-Vis spectra of the copper nanopaticles which were synthesized with different of
ratio acid ascorbic/Cu2+. The results shown that, when increased the ratio of acid ascorbic/Cu2+, the
position of the maximum absorbance peak shifted to smaller wavelengths from 582 to 571 nm with value
of wavelength were 582 nm (0.5 ); 579 nm (1.0); 572 nm (1.5); 571 nm (2.0); 572 nm (2.5) and 3.0 (571
nm) respectively. The results also shown that not any change in the wavelength of maximum absorbance
peaks when the ratio of acid ascorbic/ Cu2+ changed from 1.5 to 3.0. Thus, the best ratio of acid ascorbic/
Cu2+ for the synthesis of copper nanoparticles was 1.5.
17


Figure 3.71, 3.75, 3.76 are TEM images and size distribution of copper nanoparticles which were
synthesized with the different of ratio of acid ascorbic/Cu2+. The results shown that, the copper
nanoparticles were generated mainly in the form of spherical, uniform distribution with the average size
of 25 ± 4 nm (Figure 3.75), 21 ± 6 nm (Figure 3.71) and 5 ± 2 nm (Figure 3.76) corresponding to ratio of
acid ascorbic/ Cu2+ was 0.5; 1.0 and 1.5 respectively.

Figure 3.74: UV-Vis spectra of copper
nanopaticles were synthesized with
diffirent of the ratio of acid ascorbic/Cu2+

Figure 3.75: TEM image and
particle size distribution of CuNPs
were synthesized with ratio of acid
ascorbic/Cu2+ = 0,5

Figure 3.76: TEM image and particle
size distribution of CuNPs were
synthesized with ratio of acid
ascorbic/Cu2+ = 1,5

d. Effect of ratio of CTAB/Cu2+

Figure 3.78: UV-Vis spectra of copper nanopaticles
were synthesized with diffirent of the ratio of
CTAB/Cu2+

Figure 3.79: TEM image and particle size
distribution of CuNPs were synthesized with ratio of
CTAB/Cu2+ = 1,5

Figure 3.78 is UV-Vis spectra of the copper nanopaticles colloidal solution which were synthesized
at different of ratio CTAB/Cu2+. The results shown that, increased the ratio of CTAB/ Cu2+, the position
of the absorbance surface plasmon peak changed with wavelength value 574 nm, 572 nm, 570 nm
corresponding to ratio CTAB/Cu2+ = 0; 0.5 and 1.0 respectively. Position the maximum absorbance peak
almost did not change in the ratio of CTAB/Cu2+ from 1.5 to 2.5 with wavelength value from 567 to 568
nm. These result shown that the nanoparticles were created with uniform and smallest size at ratio of
CTAB/Cu2+ ≥ 1.5.
Figure 3.76 and 3.79 are TEM images and size distribution of the copper nanopaticles which were
synthesized without and in the presence of CTAB (CTAB/ Cu2+ = 1.5). The results shown that copper
nanoparticles generated mainly in spherical, with uniform distribution inrange of 5 ± 2 nm (Figure 3.76)
18


and 3 ± 1 nm (Figure 3.79) respectively. Thus, CTAB has an important role in the synthesis of copper
nanopaticles. As the cationic surfactant, it serves to protect and stabilize the overall process through
contractual mechanisms micelles or adsorb on the surface nanoparticles. When increased concentrations
of CTAB, greater CTAB molecules surrounded and reduced the active surface of copper nanoparticles.
Thus, copper nanoparticles were created with smaller size and more uniform.
e. Effect of ratio of Cu2+/PVP in the presence of CTAB

Figure 3.82: TEM image and particle Figure 3.83: TEM image and particle
size distribution of CuNPs were size distribution of CuNPs were
synthesized at Cu2+/PVP = 6 %
synthesized at Cu2+/PVP = 9 %

Figure 3.84: TEM image and particle
size distribution of CuNPs were
synthesized at Cu2+/PVP = 11 %

Figure 3.79, 3.82, 3.83, 3.84 are the TEM images and size distribution of the copper nanoparticles
which were synthesized with different of ratio of Cu2+/PVP. At ratio of Cu2+/PVP = 3 and 6% (Figure
3.79, 3.82), the copper nanoparticles were synthesize mainly in spherical, uniform distribution with the
average size 3 ± 1 nm. When the ratio of Cu2+/ PVP increased to 9 % and 11 % (Figure 3.83, 3.84), the
copper nanopaticles were prepared in spherical, highter concentration and cluster forming because of
hight concentration of nanopaticles forming. However, due to the synergistic of 3 protective agent PVP,
ascorbic acid and CTAB, so the nanopaticles were prepared with small size, the average size of 4 ± 1 nm
and 3 ± 1 nm respectively.
 Summary and general discussion on the results of the synthetic copper nanopaticles from copper
nitrate, copper chloride and copper sulfate precursort.
Table 3.7: Summary and general discussion on the results of the synthetic copper nanopaticles from
copper nitrate, copper chloride and copper sulfate precursort
Precursor
Copper nitrate,
/synthetic
Copper sulfate
Copper chloride
Conditions
- Trisodium citrat
- CTAB
- Glycerol
- H2O
System of
- PVP (1.000.000 g/mol) with copper
- Acid ascorbic
reaction
nitrate, PVP (58.000 g/mol), PVA
- PVP (40.000 g/mol)
(60.000 g/mol) with copper cloride
- NaBH4.
- Hydrazin hydrate.
Ratio of
Temp (oC), Ratio of
Ratio
Ratio of
Temp(oC),
trisodium
Ratio of
reducing
acid
of
copper
paremeters of reducing
citrate/
Cu2+/ PVP
agent
ascorbic/ CTAB/ sulfate/
investigating agent HH
Cu2+
NaBH4 (M)
CuSO4
CuSO4
PVP
100 ÷ 160
0 ÷ 1,5
1 ÷ 15 %
30 ÷ 80;
0,5 ÷ 3,0 0 ÷ 2,5 1 ÷ 13 %
19


o

C;
0,1 ÷ 0,7
M

Results of
UV-Vis (nm)

The best
synthesis
conditions

Results of
TEM

(copper
nitrate)
0 ÷ 1,25
(copper
cloride)
562 ÷ 564; 584 ÷ 562;
562 ÷ 580 580 ÷ 562
Temp (oC
trinatri
reducing
citrat/
agent HH
Cu2+
(M)

(copper
nitrate)
1÷7%
(copper
cloride)
562 ÷ 568;
562 ÷ 572
Ratio of
Cu2+ /PVP

0,1 ÷ 0,5

570 ÷ 580;
566 ÷ 580
Temp (oC),
reducing
agent
NaBH4 (M)

571 ÷
582
Ratio of
acid
ascorbic/
CuSO4

567 ÷
574
Ratio
of
CTAB/
CuSO4

567 ÷
573
Ratio of
copper
sulfate/
PVP

50;
0,3

 1,5

 1,5

1 ÷ 11 %

1 ÷ 13 %
(copper
nitrate)
110; 0,2
 0,5
1÷5%
(copper
cloride)
3 ± 2 nm (copper nitrate)
3 ± 1 nm (copper cloride)
2 ± 1 (copper cloride)

3 ± 1 nm

The results in table 3.7 can give some discussions on the synthesis of copper nanopaticles as follows:
 By using copper nitrate and copper chloride precursors: using solvent glycerin has high
viscosity so it reduce the collision and agglomeration of nanoparticles, hydrazine hydrate after reaction
desalination contract for the production nitrogen capable surface of copper nanopaticles protection
without oxidation. Moreover, the synergistic of protective agent trisodium citrate and PVP would
guaranteed the copper nanoparticles forming in high purity, good stability, small size with uniform
distribution.
 By using copper copper sulfate precursors: Using water solvent, reducing agent NaBH4, three
protective agent ascorbic acid, CTAB, PVP (Mw: 40,000 g/ mol). The results were obtained to allow
discussion on the synthesis of copper nanopaticles as follows:
- Solvent water with low viscosity, containing dissolved oxygen, the high mobility of nanoparticles,
so the collision of nanoparticles occurred to form larger particles and conglomeration. NaBH4 reductant in
the reaction process did not create environmental protection to copper nanoparticles from oxidation such
as glycerin solvent and reducing agent hydrazine hydrate. Thus, the system with three of the protective
agent ascorbic acid, CTAB, PVP played decisive role on the stability of copper nanoparticles forming.
- Ascorbic acid was known as antioxidant agent for the synthesis of copper nanopaticles. In addition
to, according to Jing Xiong, not only as protective agent of copper nanoparticles, ascorbic acid was also
provided electronic resources to the copper salt reduction reaction takes place faster. Accordingly, the
ability to protect and provide electron of ascorbic acid due to its molecular structure: With protective role
was the ability to form complex between polarized groups with copper ions, then adsorp on the surface of
copper nanoparticles forming. As provided electronically, it is the movement of electrons in the
conjugated system of ascorbic acid molecule. Providing electronic role of ascorbic acid will contribute to
accelerate the reduction reaction of copper sulfate salt in the synthesis of copper nanoparicles. In glycerin
20


solvent, the combination of trisodium citrate and PVP gave positive results. However, in water solvent,
the results were unsuccessful.
- The copper nanoparticles were synthesize by using ascorbic acid and PVP (Mw: 40,000 g / mol)
as protective agent only creating copper nanoparticles with the smallest average size 5 ± 2 nm . In the
presence of CTAB, the copper nanoparticles will be synergistic protected of three protective agent. Then
the copper nanoparticles were prepared in smaller size and more uniform distribution with the average
size 3 ± 1 nm. These shown that, the combination of CTAB and PVP will create good space effect to
protect copper nanoparticles forming, this effect not only created copper nanoparticles in small size but
also in high of concentration.
 With the results have presented in the thesis, it can be concluded that the best reaction system
for the synthesis of copper nanopaticles in glycerin solvent are using the combination of trisodium citrate
and PVA as protection. By using water as solvent, the best system reaction was used three protective
agent ascorbic acid, CTAB and PVP.
3.2.3.4 Investigating of stability of copper nanoparticles colloidal solution
The sample of copper nanoparticles
colloidal solution was used to investigate the
stability that were prepared with parameters:
ratio of CuSO4/PVP = 3 %, ratio of ascorbic
acid/ Cu2+ = 1.5; ratio of CTAB/Cu2+ = 1.5;
concentration of NaBH4 0.3 M, temperature
at 50

o

recorded

C. Over time, the sample was
UV-Vis

spectra

four

times

corresponding to period of time 1 month, 3
Figure 3.86: UV-Vis spectra of copper nanopaticles

months, 5 months and 6 months. The results

corresponding to period of time

was presented in Figure 3.86.
The results shown that, after 1 month and 3 months, the position of the absorbance peak almost
unchanged with values of wavelength at 569 nm. After 5 and 6 months, copper nanopaticles was
conglomerated (Figure 3.87) in wireless glue of container, the color was changed, the absorbance peak of
UV-Vis spectra located at 579 nm. In the range of wavelength from 350 to 800 nm, only a single peak of
the copper nanopaticles appeared; approximately 450 nm of wavelength does not appear peak Cu2O.
Thus, the copper nanopaticles colloidal solution had good stability over time. UV-Vis spectra could be
predicted that the copper nanoparticles were synthesize with stable size and unchanged after 3 months.
The copper nanoparticles was also protected, not oxidized surface after 6 months of storage.
3.3 The results of antifungal activity and killing ability against Corticium salmonicolor
The copper nanoparticles colloidal solution were synthesized from copper chloride precursors in
PVA protective agent, trisodium citrate dispersant (average size 3 ± 1 nm) will be selected to test the
antifungal activity and killing ability against Corticium salmonicolor.
21


3.3.1 The antifungal activity
Table 3.8: The ability to inhibit growth of corticium salmonicolor at different concentrations
Sample

Diameter of control
sample (cm)

Diameter of samples containing copper
nanoparticles (cm)

fungal growth
inhibition

3 ppm

5

0,5

90 %

5 ppm

5

0

100 %

7 ppm

5

0

100 %

Table 3.8 shown the results of antifungal of copper nanopaticles at different concentrations. The
results shown that, the copper nanopaticles colloidal solution shown complete inhibition at 5 ppm and 7
ppm. With concentration of copper nanoparticles lower 3 ppm, the copper nanoparticles colloidal solution
shown lower activity with 90% complete inhibition. Good antifungal ability of copper nanoparticles
colloidal solution can be explained by the nanoparticles will create interactions which cause biological
changes including structural changes as well as the replacement of functions membrane. Simultaneously
Cu2+ ions released from the nanoparticles will react with oxygen creating, harming the cells, causing the
destruction of proteins, lipids, and nucleic acids. Another theory is that the nanoparticles will create links
with the original sulfur bond formation Sulfur-NPS, reducing the total lipid content with abnormal
accumulation of saturated fatty acids (saturated fatty acids), atypical for membrane lipid biosynthesis
source.
The antifungal results of copper nanoparticles colloidal solution was positive which compared to
the results was done by Sahar M. Ouda that researched on Alternaria alternate and Botrytis cinerea. Ouda
had tested active of nano colloidal solution of silver, copper and composite silver/copper. The results of
diameter measurement after 6 days fungal development implants, silver colloidal (38 nm) at concentration
of 15 ppm for the ability to inhibit 52.9% and 59.6 % with fungi Botrytis cinerea and Alternaria alternate
respectively. Similarly, copper colloidal (20 nm) at concentration of 15 ppm showed inhibition with 13.75
and 4.7%. Mix of colloidal solution silver/copper shown the inhibition 38.12 and 27% respectively. The
superior efficacy when tested antifungal activity can be explained by the small size of copper
nanoparticles. Nanoparticles were smaller in size, the larger the surface area, so it easy to interact with the
cell membrane of microorganisms, such as the destruction of microbial cells not only by the release metal
ions in solution.
1.3.2 Fungal Killing Ability
Figure 3.91 to 3.95 (in the thesis) shown fungal killing ability of copper nanopaticles colloidal
solution at different concentrations. Results shown that, corticium salmonicolor still developing after 2
times of spray at concentrations of 3 and 5 ppm. With 7 ppm concentration, the fungal killing ability was
completely after two times of spray. When the concentration of copper nanopaticles colloidal solution
22


increased to 10 ppm and 20 ppm, the fungal killing ability was completely at the first time of spray. Thus,
to achieve fungal killing ability need to use concentration of nanopaticles colloidal solution at higher
concentrations (10 ppm) compare to antifungal activity (5 ppm).

23


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