VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITY
HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY
FACULTY OF CHEMICAL ENGINEERING
DEPARTMENT OF INORGANIC ENGINEERING
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THESIS PROPOSAL
SYNTHESIS OF APATITE NANOPARTICLES
AS A PHOSPHORUS FERTILIZER
Performing Student: NGUYEN BUI DUY ANH
Instructing Lecturer: Assoc. Prof. LE MINH VIEN
Student Code: 1852007
Class Code: CC18HC12
2022 - HO CHI MINH
1
VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITY
HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY
FACULTY OF CHEMICAL ENGINEERING
DEPARTMENT OF INORGANIC ENGINEERING
-------------------o0o-------------------
THESIS PROPOSAL
SYNTHESIS OF APATITE NANOPARTICLES
AS A PHOSPHORUS FERTILIZER
Performing Student: NGUYEN BUI DUY ANH
Instructing Lecturer: Assoc. Prof. LE MINH VIEN
Student Code: 1852007
Class Code: CC18HC12
2022 - HO CHI MINH
2
INSTRUCTOR COMMENT
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ABSTRACT
The tremendous potential for hydroxyapatite nanoparticles to be used as nano-fertilizers
with significant effects on increasing plant production is astounding. Microwave and
ultrasonic techniques were used to create these nano-compounds, which resulted in a
reduction in the products' particle size distribution. Considering the beneficial effects of
nano-hydroxyapatite fertilizers and high production levels, it is advised to use nanophosphate fertilizers in food resource management to achieve a favorable quantitative
yield. Additionally, they can be seen as a good way to address environmental issues.
4
TABLE OF CONTENTS
ABSTRACT
LIST OF TABLES
LIST OF FIGURES
LIST OF ABBREVIATIONS
CHAPTER 1: OVERVIEW…………...……………………………………………1
1.1 Introduction:…………...………………………………………………………..1
1.2 Structure & Chemical Composition HAP:……………………………………4
1.3 Synthesis Technique HAP:……………...….....…………...…………………...5
1.3.1 With CMC – stabilized method:….....…………...…………………...5
1.3.2 With microwave method:..…………...……………………………….5
1.3.3 With ultrasound method:..…………...……………………………….5
1.3.4 With wet method:…….…………...…………………………………...6
CHAPTER 2: EXPERIMENTAL METHOD………...…………...……………...8
2.1 Materials & Methods:……………...………………………………………….. 8
2.1.1 Materials:…………...……………………………………………….... 8
2.1.2 Preparation:…………...……………………………………………… 9
2.2 Characterization Techniques:…………...……………………………………. 9
REFERENCE…………...………………………………………………………….11
5
LIST OF TABLES
Table 1. Synthetic techniques used for the synthesis of HA and characteristics of the
resulting material
Table 2. Chemicals used during the synthesis of hydroxyapatite nanoparticles
Table 3. Classification, advantages, and disadvantages of several methods used to analyze
HA nanoparticles
LIST OF FIGURES
Fig 1. A graphic comparison of the environmental characteristics of soluble P, nano-sized
solid P, and solid P
Fig 2. Crystal structure of HA showing the c-axis perpendicular to 3 a-axes lying at 120°
of each other (left)& the projection of the HA structure on the 001 plane (right)
6
LIST OF ABBREVIATIONS
Abbreviations
Sign
Phosphorus
P
Hydro Apatite
HA
Hydro Apatite Phosphorus
HAP
Polyethylene Glycol
PEG
Simulated Bodily Fluid
SBF
Chemical Precipitation
CP
Hydrothermal
HT
Electrospinning
ED
Electrospraying
ESp
Solid State
SS
Microwave Irradiation
MI
Self Propagating Combustion
SPC
Emulsion & Microemulsion
EMe
Flux Cooling
FC
7
CHAPTER 1: OVERVIEW
1.1 Introduction:
P was discovered in the middle of the 17th century and has long been utilized to
improve agriculture productivity. The usage of processed inorganic P fertilizers has grown
dramatically, especially since the Green Revolution, helping to significantly increase
global food production. [1] However, the available supplies of phosphate rock, which are
used to manufacture P fertilisers, are limited. The P reserves are predicted to be mostly
depleted in the next 50–125 years at the current rate of consumption. [2] Despite the fact
that P shortage is becoming a worldwide problem, the current fertiliser technology and
farming techniques may lead to low P usage efficiency. For instance, the first crop after the
application of P often only absorbs a small proportion of it (5–30%). [3] The solubility of
newly formed P compounds, the kind of plant and other soil conditions all affect how well
phosphorus fertilizers are recovered from soils. [4] [5] Moreover, additional inputs of P
fertilizers may be required throughout time to maintain appropriate levels of P in soil
solution. The oversupply of P fertilizers not only ends up making P shortage worse, but it
also typically causes negative environmental issues such eutrophication through leaching,
runoff and erosion. [6] [7] In some conditions, when P fertilisers are applied in excess of
what the plants require, P leaching may be aggravated by the buildup of available P. [8]
Numerous studies have demonstrated that lowering P inputs can effectively lower
eutrophication. [9]-[12] Once P enters water bodies, eutrophication can endure for years
to decades due to the mobilization of previously deposited P (legacy P), even after inputs
decrease. [13] [14].
Typically, commercially accessible P fertilizers such as MAP (Monoammonium
Phosphate, NH3H2PO4), DAP (Diammonium Phosphate, (NH3)2HPO4), or TSP (Triple
Superphosphate, Ca(H2PO4)2) are examples of P fertilizers that are readily absorbed by
plants because they are easily accessible in the soil solution. Although these fertilizers are
easily available to plants, their high mobility within the soil enables them to eventually end
up in bodies of water via runoff and seepage, causing ecological threats such as
1
eutrophication. To address this issue, solid phosphorus fertilizers (Ca5(PO4)3X with X = F/
Cl/ Br/ OH) such as rock phosphate and apatite have been utilized, but their usage is
restricted due to the lesser accessibility of phosphorus to plants. [15]
Fig 1. A graphic comparison of the environmental characteristics of
soluble P, nano-sized solid P, and solid P
The schematics in Fig. 1 demonstrate a hypothetic evaluation of soluble P, nanosized solid P, and regular solid P in fertilizer performance and eutrophication risk, showing
that using nano-sized solid P as fertilizer would be a decent solution between agricultural
benefits and sustainability issues. A P nanoparticle suspension, in particular, is easily
delivered to root zones using conventional methods because it has the same mobility in soil
columns as an aqueous solution due to nano-scaled particle size (e.g., spray or irriga- tion).
Furthermore, the nanoparticles are ecologically friendly since solid P is substantially less
accessible to algae than liquid P. [16] Eutrophication in fresh surface waters is mostly
caused by algae-bioavailable P.
The introduction of innovative fertilizers based on nanotechnology has given
promising results in terms of increasing global agricultural productivity. According to
researches, fertilizer containing hydroxyapatite nanoparticles (HANPs) can act as a
superior phosphorus nutrient supplier in agricultural applications by increasing crop yield
2
and biomass output in plants. The improved physicochemical features of nanoparticles
(NPs) offer a considerable potential to reduce the repercussions of traditional fertilizers,
such as nutrient loss to the environment.
Many techniques for synthesizing HA have been documented in the literature,
including sol-gel [17] [18], wet method [19] [20], ultrasound [21], microwave [22],
precipitation [23] [24] and CMC - stabilized [25]. Some of these approaches, such as
hydrothermal and reverse microemulsion procedures, have produced weakly agglomerated
and nano-sized HA particles [26].
The most frequently described method for preparing HA particles is precipitation.
This procedure is easy, low-cost, and suitable for industrial production; nevertheless, the
resulting particles are of poor quality, with a big particle size, a wide particle size
dispersion, and a high number of agglomerates [26]. Although it is well known that
ultrasonication is especially effective in breaking up aggregates and reducing the size and
polydispersity of nanoparticles [27], only a few studies have been conducted on HA
deagglomeration during the precipitation technique.
So far, the precipitation process has been used to produce nano-sized HA particles
using simulated bodily fluid (SBF). CaPTris solution was performed as an alternative
calcium phosphate growth medium for the first time in this study. To minimize particle
agglomeration, polyethylene glycol (PEG) was utilized as a dispersion, and the suspension
was ultrasonically treated.
3
1.2 Structure & Chemical Composition HAP:
As mentioned earlier, HA is a member of the apatite family (consists of Ca and
phosphates) with the general formula Ca5(PO4)3OH, and unit cell formula
Ca10(PO4)6(OH)2. The arrangement of the Ca and phosphate atoms in the HA unit cell is
such that the four Ca atoms at the M1 position are surrounded by nine phosphate O atoms,
and the other six Ca atoms are surrounded by the remaining six O atoms at the M2 position.
All Ca atoms' crystallographic locations are M1 and M2 (Fig. 2). HA has traces of
contaminants such phosphite ions (PO33-), chloride ions (Cl-), fluoride ions (F-), and
hydroxyl ions (OH-), regardless of where it came from. While F- and OH- are known to
increase apatite strength, PO33- and Cl- have been shown to weaken the HA structure. [28]
Fig 2. Crystal structure of HA showing the c-axis perpendicular to 3 a-axes lying at 120°
of each other (left)& the projection of the HA structure on the 001 plane (right) [28]
HAP crystallizes in the form of hexagonal structure, even though with some
exemption in a monoclinic structure . The structure has a place with the hexagonal space
group P63/m, with cell parameters of a=b=9.418 Å y, c=6.884 Å, with hexagonal rotational
symmetry and a reflection plane. [28]
4
1.3 Synthesis Technique HAP:
1.3.1 With CMC – stabilized method:
Separate solutions of CMC, PO43-, and Ca2+ were produced in DI water using
NaCMC, H3PO4, and Ca(OH)2. The nanoparticles were prepared under controlled
temperature, with 25 mL of Ca2+ solution dropwise added to 50 mL of CMC solution while
constantly stirring. After 12 hours of agitation, 25 mL of the phosphate solution was
dropwise added to the mixture while being constantly mixed. According to the
stoichiometry of hydroxyapatite, the molar ratio of Ca2+ to PO43- was 5:3. [25]
1.3.2 With microwave method:
A 50 mL solution of (Ca(NO3)2.4H2O) with a concentration of 0.05 M was produced
in a conventional synthesis. The preceding solution was then added with 3.75g Glycine
(NH2–CH2COOH). Following that, 3.6 g acrylic acid (CH2 = CH–COOH) was applied to
produce an alkaline medium. Then 50 mL of 0.03 M diammonium hydrogenphosphate
((NH4)2HPO4) solution was added to create a milky solution. A magnetic stirrer was used
to agitate the mixed solution for 20 hours. Finally, the solution was placed in a 200-W
microwave reactor at 100oC and 1atm pressure in about 10 minutes. [22]
1.3.3 With ultrasound method:
Firstly, a 100 mL Ca(NO3)2.4H2O solution with a concentration of 0.05 M was
produced and stirred with a magnetic stirrer. Simultaneously, 7.5 g of Glycine was added
to the solution and 7.5 g of acrylic acid was added after that. Then 100 mL of 0.03M
(NH4)2HPO4 was added to create a milky solution. A magnetic stirrer was used to agitate
the resultant solution for 20 hours. After that, the solution was placed in an ultrasound
batch for 1 hour (power: 160 W, frequency: 20 kHz). After washing, the precipitate was
separated by centrifugation then dried and calcined. [21]
5
1.3.4 With wet method:
Firstly, 100 mL (Ca(NO3)2.4H2O) with a concentration of 0.05 M was prepared and
positioned under a magnetic stirrer for the wet method synthesis of the products.
Simultaneously, 7.5 g of Glycine was added to the solution. After that, 7.5 g of acrylic acid
was added. To generate a milky solution, 100 mL of (NH4)2HPO4 at a concentration of 0.03
M was added next. A magnetic stirrer was used to agitate the resultant solution for 20 hours.
After washing, the precipitate was separated by centrifugation then dried and calcined. [19]
Size
Time
Method
Crystallinity
Phase
Temp
(<>24)
Size
Morphology
(m)
Degree
Purity
CP
>
RT
>0.1
Low
Variable
ESp
>
_
75x40 nm
_
_
ES
>
_
_
_
High
High
Cost
Distribution
Diverse
Variable
Low
_
Low
Fiber
Variable
Variable
Diverse
Narrow
Variable
_
Variable
10x
10-30
MI
_
100x25 nm
Hexagonal
FC
<
500
18.0x2.1
High
_
Cylinders
HT
<
SS
>
SG
>
150400
10501250
37-85
>0.05
High
High
Needle Like
Wide
High
>2.0
High
Low
Diverse
Wide
High
>0.001
Variable
Variable
Diverse
Narrow
Variable
6
SPC
<
170-
>0.45
500
Variable
High
Diverse
Wide
Low
Low
Variable
Needle Like
Narrow
High
>1.0(Emu)
EMe
>
RT
>0.005(Micr)
Table 1. Synthetic techniques used for the synthesis of HA
and characteristics of the resulting material [28]
Eggshells, bovine bones, and other naturally occurring organic materials can be used
in the synthesis of HAP, as well as inorganic components. HAP derived from natural
sources is not stoichiometric (Ca/P ratio is 1.67) since it also contains small amounts of
other ions. Although these materials are believed to be both biocompatible and bioactive
in both sources and are regarded as suitable for in vitro applications, the main challenge is
the high expense of the synthesis procedure to generate HAP from the inorganic Ca and P
based sources [29].
The need for obtaining HAP through an effective, simple, affordable, and
environmentally friendly technique is rising daily. The synthesis techniques and
procedures of HAP are progressively enlarged as a result of the innovation, and a
considerable advancement has been realized in the area of therapeutic application.
Researchers have worked for decades to create the ideal HAP crystal, which has a
consistent composition, a specified surface area, an adaptive shape, a wide range of various
particle sizes, fine grain, superior performance [30].
7
CHAPTER 2: EXPERIMENTAL METHOD
2.1 Materials & Methods:
2.1.1 Materials
The following chemicals used during the synthesis of hydroxyapatite nanoparticles
were NaCl, NaHCO3, KCl (99%), MgCl2 (98%), CaCl2 (≥98%), Na2 SO4 , Tris ((CH2 OH)3
CNH2 ), HCl (37%), K2 HPO4, Polyethylene Glycol (Mw = 2000, PEG = 2000) and Ethanol.
SBF
Reagent
CaPTris
Amount
Reagent
Amount
NaCl
8.035 g
Tris ((CH2 OH)3 CNH2 )
24.22 g
NaHCO3
0.355 g
HCl
6.570 g
KCl
0.225 g
K2 HPO4
1.740 g
K2 HPO4
0.176 g
CaCl2
2.775 g
MgCl2
0.145 g
_
_
HCl
39 ml
_
_
CaCl2
0.292 g
_
_
Na2 SO4
0.072 g
_
_
Tris
6.118 g
_
_
Cl
0–5g
_
_
Table 2. Chemicals used during the synthesis of hydroxyapatite nanoparticles
8
2.1.2 Preparation:
SBF was the primary calcium phosphate growth medium used in our research. SBF
was made by combining deionized water with NaCl, NaHCO3, KCl, K2HPO4, MgCl2,
CaCl2, and Na2SO4. Tris, HCl, K2HPO4, and CaCl2 were combined with deionized water
to create "CaP-Tris solution," another calcium phosphate growth media. After each reagent
had completely dissolved in 1000 and 500 ml of deionized water, respectively, in the order
listed in Table 2, it was time to add the reagents for the two procedures (SBF and CaPTris).
In order to create the suspension, known amounts of CaCl2 (4.4 and 2.2 g) and K2HPO4
(4.14 and 2.07 g) were added to the SBF or CaPTris solution, respectively. The suspension
was then kept at 37oC for a day. The resultant suspension was centrifuged, and the
precipitate was then five times washed in distilled water and twice washed in ethanol.
Following all washing procedures, PEG (1 weight percent) and ethanol (1:2.5 by volume,
precipitate:ethanol) were added to the precipitate in the centrifuge tube. After that, an
ultrasonic agitator was used to treat the suspension in the tube for 5 minutes. The SBF
precipitate that resulted was dried at 50°C for 24 hours. The precipitate formed after using
CaPTris was dried at 70°C for 12 hours and then sintered at 700°C for 2 hours. Agate
mortar was used to crush the sintered goods. For 15 minutes, ultrason-ication was used to
lower the particle size of the crushed particles. The ultrasonic homogenizer used for the
procedure ranged in frequency from 20 kHz (SONICS vibra-cell) to 30 kHz (Ultrasound
Technology UP100H). [31]
2.2 Characterization Techniques:
In the wave number range 4000-400cm-1, Fourier-transformed infrared
spectroscopy (FTIR) was used. Solid sample experimental spectra were obtained by
making KBr plates with a 100:3 'KBr-to-HA powders' ratio. [31]
9
By using an X-ray diffractometer (XRD, Dmax 2200 XRD) with a step size of 0.02o
2 and a speed of 10o 2 seconds per min, the samples were analyzed. To produce X-rays,
a Cu K tube running at 40kV and 80mA was employed. [31]
By using a scanning electron microscope (SEM) and a particles size analyzer (Nano
Series Nano-S), we were able to examine the morphology and sizes of the HA powders.
EDX analysis was used to determine the Ca/P ratio. [31]
Technique
Advantages
Disadvantages
Measures the intensity
throughout a constrained
spectrum of wavelengths at a
FTIR
time without requiring external
Inorganic materials are not
easily analyzed by FTIR
spectroscopy
calibration; gives reliable results
and detects contaminants at
even low amounts.
Peak overlay may occur, and it
XRD
Effective and quick (20 min)
is worse for high angle
procedure, delivers a clear
reflections, therefore
mineral detection; data
homogeneous and single phase
interpretation is rather simple
materials are ideal for
identifying an unknown.
SEM
Direct visualization, high
NP aggregation during the
resolution
sample preparation
Table 3. Classification, advantages, and disadvantages of
several methods used to analyze HA nanoparticles [28].
10
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