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Characteristic of Eggshell in Substitution of Hydroxyapatite in Biomedical Appliances
Syed Mohd Hasif Wafa Bin Syed Mohd Hassana, Amalina Binti Amirb, Robi Arsam Bin Armanc, Saiful Bahari Bin Mohd Latifd,
Muhammad ‘Abdul Hakim Hashim and Muhammad Hussain Ismaile
Faculty of Mechanical Engineering, Universiti Teknologi Mara (UiTM), 40450 Selangor, Malaysia
[email protected] , [email protected] , [email protected] , [email protected] , [email protected]
Keywords: Eggshell waste, Hydroxyapatite, Preparation of hydroxyapatite, HAp
Abstract. Hydroxyapatite (HAp) is one of the most versatile materials used for implantation
purpose due to its similarity to natural bone material with a composition around 70% of our bone.
Not only that, it is regarded as attractive biomedical materials because of their outstanding
bioactivities and non toxicity. The purposes of this particular project are mainly to produce HAp
powder by utilizing eggshell waste as its main raw material as well as to study the effectiveness of
eggshell substitution in HAp on mechanical behaviour. The process involves drying and thermal
decomposition of eggshell followed by hydrothermal reaction at low temperature with di-
ammonium hydrogen phosphate and water. After that, the next process that takes place will involve
compacting of the powder at pressure of 80 kg/cm2 and sintering at temperature of 900-1300
oC.
Therefore, by using the suitable synthesizing method together with the workable sintering schedule
for each synthesizing process, the optimized microstructure and properties of sintered HAp can be
prepared.
Introduction
In the ever evolving changes and researches carried out in the biomedical field, there have been
tremendous advancements achieved. Until now, there have been many biomedical achievements
that have been successfully achieved. One of them is bone grafting. The process of bone grafting is
widely used especially orthopaedic surgeries [1]. It is a procedure whereby a specific area of a bone
is transplanted to another area for the purpose of helping the bone to heal from various types of
bone diseases, injuries, and deformity or during a surgical procedure such as spinal fusion [2]. The
main broad categories of bone grafts are autografts, allografts and synthetic grafts [3].
Due to the similarity to natural bone material, hydroxyapatite (HAp) is one of the most flexible
materials used for implantation purpose [4]. HAp is the main inorganic constituent of bones in
humans with the estimated chemical formula Ca10(PO4)6(OH)2 or Ca5(PO4)3(OH). For the fact that
synthetic HAp is capable of undergoing bonding osteogenesis and it’s relatively insoluble in vivo, it
has been successfully acquired in hard tissue surgery [4]. The material is widely used for bone and
tooth implants. This is because it has a similar resemblance with human tooth and bone mineral
besides having proven to biologically well-matched with these tissues [4].
A typical hen eggshell is made up of ceramic materials which consist by a three layered
structure. These are the cuticle which is on the outer surface, a spongy (calcareous) layer and an
inner lamellar (or mammillary) layer [5]. The following has been reported to be the chemical
composition by weight of by product eggshell. Calcium carbonate (94%), magnesium carbonate
(1%), calcium phosphate (1%), and organic matter (4%) [5].
Previous studies have shown that HAp ceramics have no trace of toxicity, inflammatory
response, pyrogenetic response. It contains outstanding fibrous tissue formation between implant
and bone. Not only that, it also has the ability to bond directly to the host bone [4]. Problems such
as coating adhesion, rapid dissolution (subsequent lost of bone bonding), fatigue failure and the
creation of particulate debris limits the long term performance even though it is proven that HAp is
capable in promoting bone attachment [4].
Advanced Materials Research Vol. 651 (2013) pp 216-220Online available since 2013/Jan/25 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.651.216
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Experimental Procedure
Materials. Hen’s Eggshell, Di-ammonium Hydrogen Phosphate (DAP), Distilled Water.
Preparation of HAp powder. Eggshell was collected in bulk and washed thoroughly. Then, it is
placed in high temperature oven for 60 minutes at a temperature of 80oC. The eggshells were then
be calcined in annealing furnace at a temperature of 900oC for 2 hours. Using hydrothermal method,
HAp powder was produce by mixing 41.16g of calcined eggshell (CaO) and 58.8g of di-ammonium
hydrogen phosphate ((NH4)2HPO4) with 100ml distilled water (H2O) at temperature 90oC. The
chemical formula is shown in the Eq. 1. The mixtures were dried in oven at temperature 200oC
over night. The dried mixture was then ball milled at a speed of 350 rpm for 5 minutes to obtain
fine powder. The HAp was identified using the x-ray diffraction and the micrographs of the powder
and its particle size distribution were identified using FESEM and Malvern particle size analyzer.
5CaO + 3(NH4)2HPO4 + 2H2O Ca5 (PO4)3OH + 6NH4OH (1)
HAp Powder Compaction. The produced HAp powder was compacted using manual hydraulic
press at a pressure of 80 kg/cm2 into cylindrical specimen of 1.1mm in diameter and 0.9mm in
height using a cylindrical mould. The micrograph of the compacted specimen was then observed in
FESEM.
Sintering. The specimens produced were divided into 5 sets of sintering temperatures. The
specimens were sintered at sintering temperature range from 900oC to 1300
oC with an increment of
100oC at a heating rate of 5
oC/min and holding time of 3 hours. For each temperature, micrographs
of the sintered specimen were observed using FESEM and was analyzed using x-ray diffraction.
Linear shrinkage percentage was measured depending on diameter change by using micrometer,
before and after sintering using Eq. 2 [6].
Linear shrinkage % = D - D o *100 (2)
D
Where: Do: Sample diameter after pressing (mm)
D: Sample diameter after sintering (mm)
Compress test. The mechanical strength of the sintered specimen was tested using compression
test. The compression test was performed using an Instron testing machine that was controlled by
Bluehill software at a crosshead speed of 1 mm/min.
Results
X ray Diffraction (XRD). X-ray powder diffractometry was carried out in a Rigaku Model Ultima
IV. X-ray diffraction pattern of the egg shell after calcined at 900oC in Figure 1 shows intensity
peaks corresponding to JCPDS 37-1497 files for CaO (17.89o, 33.96
o, 50.69
o, 62.34
o), with some
fraction of other species Ca(OH)2 (28.53o, 54.44
o).
Fig. 1: The XRD pattern of the uncrushed egg shell after calcined at 900oC
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The XRD of the sintered HAp at various temperatures was taken to observe the effect of the
sintering temperature to the produced HAp. Compared with the xrd powder in Figure 2, the sintered
HAp showed the increase of the intensity of HAp and many HAp peaks emerge. But there were also
some unknown and some portlandite and lime phase emerges as well. From the XRD pattern shown
in Figure 3 until Figure 7, the intensity of the HAp peak decreased tremendously at temperature
1300oC.
Fig. 2 : The XRD pattern of the produce HAp
powder
Fig. 3: The XRD pattern of Sintered
Compacted HAp at Temperature 900oC.
Fig. 4: The XRD pattern of Sintered
Compacted HAp at Temperature 1000oC
Fig. 5: The XRD pattern of Sintered
Compacted HAp at Temperature 1100oC
Fig. 6: The XRD pattern of Sintered
Compacted HAp at Temperature 1200oC
Fig. 7: The XRD pattern of Sintered
Compacted HAp at Temperature 1300oC
Field Emission Scanning Electron Microscopy (FESEM). The FESEM investigation of the
material used in this study from raw eggshells to HAp powder compact samples sintered at various
temperatures are shown in Figures below. The powder produced from calcinations of the eggshell at
temperature 900oC is shown in Figure 8a. The powder particle shows an irregular shape. As for the
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HAp powder in Figure 8b, the particle shape of the powder is in irregular shapes. From the image,
the shape of CaO particle had change when it has been react with di-ammonium hydrogen
phosphate. The surface micrograph image of the compacted HAp in Figure 8c shows some porosity.
In Figure 8d the pores can still be seen after it was sintered at temperature 900oC. As sintering
progresses to higher temperatures, (Figure 8e to Figure 8h) the grains grow bigger and pores shrink.
Figure 8: FESEM micrograph of; a) CaO powder, b) HAp powder, c) Compacted HAp powder,
d) Compacted HAp sintered at 900oC, e) Compacted HAp sintered at 1000
oC, f) Compacted HAp
sintered at 1100oC, g) Compacted HAp sintered at 1200
oC, h) Compacted HAp sintered at 1300
oC
a) b)
c)
h) g)
f) e)
d)
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Summary
From the whole observation made throughout the study, we can see that synthesization of HAp can
be successfully done using waste eggshells through chemical route. Through this technique, a high
value material can be produced by using a very low final cost in the production of the powders. As
temperature increases, the relative shrinkage of the compressed HAp also rises. As porosity
represents one of the main factors defining bioactivity, therefore this fact is important for the for
medical application purposes. At higher temperatures, the pores decrease while grain growth
increases. Overall, from this study, it can be concluded that HAp powder that was produced from
the mixture of CaO produced from eggshells can react towards sintering temperature. Based on the
intensity of HAp from XRD analysis, it can be seen that specimen at 1200oC showed the highest
HAp intensity.
Acknowledgements
The research developed in the Center of Advanced Materials Research (CAMAR), Faculty of
Mechanical Engineering, Universiti Teknologi MARA, Malaysia under the support of Excellence
Fund Research Grant.
References
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Engineering Materials and Application 10.4028/www.scientific.net/AMR.651 Characteristic of Eggshell in Substitution of Hydroxyapatite in Biomedical Appliances 10.4028/www.scientific.net/AMR.651.216
