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Synthesis and Characterization of Titanium Dioxide Nanoparticles in Wood
Protection Application
Tan Kah Yee (39030)
A final project report submitted to fulfill the requirement for the degree of Bachelor of
Science with Honours (Resource Chemistry)
Supervisor: Prof. Dr. Pang Suh Cem
Co. Supervisor: A.P. Dr. Andrew Wong
Resource Chemistry
Department of Chemistry
Faculty of Resource Science and Technology
University Malaysia Sarawak
2015
I
APPROVAL SHEET
Name of Candidate : Tan Kah Yee
Title of dissertation : Synthesis and Characterization of Titanium Dioxide
Nanoparticles in Wood Protection Application
(Professor Dr. Pang Suh Cem)
Final Year Project Supervisor
(Dr. Sim Siong Fong)
Coordinator of Resource Chemistry
Faculty of Resource Science and Technology
II
ACKNOWLEDGEMENT
I am grateful for this opportunity to express my acknowledgements to a number of people
who support, encourage and guide me throughout my Final Year Project (FYP). Firstly, I
would give credits to my supervisor, Dr. Pang Suh Cem, from Faculty of Resource Science
and Technology (FRST), Department of Chemistry, UNIMAS for providing guidance in
titanium dioxide nanoparticles that are constructive and sustained interest in helping me to
complete this thesis. Secondly, is my co-supervisor, Associate Professor Dr. Andrew
Wong, from Faculty of Resource Science and Technology (FRST), Department of Plant
Science and Environmental Ecology, UNIMAS for providing me the knowledge about
wood science, wood treatment and leaching test methods so that I can successfully
complete this thesis.
It is also my pleasure to express my appreciations to Mohd Firdaus Rizwan bin Rosli, who
was my senior and has done some research in titanium dioxide nanoparticles ,so he has
shared his knowledge in the methodology of preparing titanium dioxide nanoparticles with
me ; Miss Kong Ying Ying and Miss Lim Li Shan, master students; Miss Voon Lee Ken
and Mr. Lai Huat Choi, PhD students; Mr. Wahap, Mr. Tommy, Madam Ting Woei and
other laboratory assistants of Physical Chemistry II Laboratory at FRST, UNIMAS for
their kind assistances in the usage of characterization instruments such as Scanning
Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Inductively Coupled
Plasma Optical Emission Spectrometry (ICP-OES), Transmission Electron Microscopy
(TEM), Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectrophotometer.
Last but not least, I would like to express my gratitude to my parent for their financial
supports throughout the final year project.
III
DECLARATION
I hereby declare that this Final Year Project 2015 dissertation is based on my original work
except for quotations and citations, which have been duly declared that it has not been or
concurrently submitted for any degree at UNIMAS or other institutions of higher
education.
Tan Kah Yee
Resource Chemistry
Faculty of Resource Science and Technology
University Malaysia Sarawak
IV
LIST OF ABBREVIATIONS
AWPA American Wood Protection Association Standards
Ag Silver
C Carbon
CCA Chromated Copper Arsenate
EWC Engineered Wood Composites
EDX Energy Dispersive X-ray
FTIR Fourier Transform Infrared Spectroscopy
H2SO4 Sulphuric acid
H2O2 Hydrogen peroxide
HNO3 Nitric acid
ICP-OES Inductively coupled plasma atomic emission spectroscopy
O Oxygen
OPM Oscillating Pressure Method
SEM Scanning Electron Microscopy
SCCNFP Scientific Committee Cosmetic Product and Non-food Products
Si Silicon
TEM Transmission Electron Microscopy
TTIP Titanium Isopropoxide
Ti Titanium
Ti4+
Titanium ( IV)
TiO2 Titanium dioxide
UV-spec Ultraviolet-visible Spectrophotometry
UV Ultraviolet
λmax Lambda max
VOC Volatile Organic Compounds
V
LIST OF FIGURES AND TABLES
Figure 2.1.3 Structures of TiO2 crystals in the form of (a) Rutile (b) Anatase and (c) Brookite
Figure 3.1.1 Flow chart of the steps involved in preparation of TiO2 nanoparticles via sol-gel
process
Figure 3.3.3 Summary of wood preservative treatment by vacuum impregnation
Figure 3.3.4 Summary of post treatment conditioning
Figure 3.3.5 Summary of chemical leaching
Figure 3.3.6 Summary of acid digestion
Figure 4.1(a) Peptization process taken place for 4 days
Figure 4.1(b)(I) Transparent and bluish TiO2 sol after 4 days
Figure 4.1(b)(II) Gel-like TiO2 sol after dialysis
Figure 4.2.1 SEM micrographs of TiO2 nanoparticles from TiO2 sols at various magnifications
(a, b) Non-dialyzed, (c, d) Dialyzed sol and (e, f) Commercial titanium dioxide
powder
Figure 4.2.2 SEM micrographs of wood sample, Jelutong (a, b) Cross Section(c, d) Radial
section (e, f) tangential section before and after titanium dioxide nanoparticles
impregnated, (a, c, e) Untreated Wood, (b, d, f) Treated Wood
Figure 4.3 TEM micrographs of TiO2 nanoparticles from TiO2 sols at various magnifications
(a, c) Non-dialyzed and (b, d) Dialyzed sol
Figure 4.4
FT-IR spectra of different titanium dioxide nanoparticle samples
Non-dialyzed (a) and Dialyzed (b)
Figure 4.5.1.1 Scanning UV spectra of non-dialyzed TiO2 sol by sol-gel process at various aging
time
Figure 4.5.1.2 Scanning UV spectra of dialyzed TiO2 sol by sol-gel process at various aging time
Figure 4.5.1.3 λmax of Non-dialyzed and dialyzed titanium dioxide nanoparticles for freshly
prepared, first week and second week
Figure 4.6.1 Energy dispersive X-ray element analysis of untreated wood
Figure 4.6.2 Energy dispersive X-ray element analysis of treated wood
Figure 4.8 Mean Concentration of TiO2 / Ti Nanoparticles in Leachate versus Time
Table 4.4 FTIR absorption peaks of TiO2 nanoparticles samples
Table 4.7 (a) Individual retention of TiO2 nanopartcles for the wood blocks before chemical
leaching
Table 4.7 (b) Individual retention of Ti nanopartcles for the wood blocks before chemical
leaching
Table 4.7.1
Individual retention and individual concentration of Ti nanoparticles for wood
blocks before leaching
Table 4.8 (a) Concentration of TiO2 nanoparticles impregnated in wood blocks before leaching
Table 4.8 (b) Concentration of Titanium impregnated in wood blocks before leaching
Table 4.9 (a) Total Percentage of TiO2 Nanoparticles leached out
Table 4.9 (b) Total Percentage of Ti Nanoparticles leached out
VI
SYNTHESIS AND CHARACTERIZATION OF TITANIUM DIOXIDE
NANOPARTICLES IN WOOD PROTECTION APPLICATION
TAN KAH YEE (39030)
Resource Chemistry
Faculty of Resource Science and Technology
University Malaysia Sarawak
ABSTRACT
Wood is an indispensable tool for human due to its aesthetic value, its properties and availability functions.
However, wood will be degraded by microbes or termites. There were many studies for wood protection in
the aspect of termite resistance, decay resistance, antibacterial, antifungal and chemical leaching. For
example, wood timber is also being treated with inorganic biocides (copper based complex with chrome or
arsenate). Their release could cause pollution to the environment. As alternatives, environmentally friendly
organic biocide (e.g. emulsion of organic biocides and copper salt) and engineered nanomaterial have been
investigated. In this study, the titanium dioxide nanoparticles synthesized were non-uniform in sizes or
irregular shapes and, not well-dispersed and the mean sizes of dialyzed titanium dioxide nanoparticles were
in the range of 6 nm to 10 nm. Titanium dioxide nanoparticles produced were impregnated within the Dyera
costulata (Jelutong) wood blocks through vacuum impregnation, the results showed there was low leaching
rate of titanium dioxide nanoparticles leached out from the wood block over two weeks which was detected
by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).
Keywords: Inorganic biocides, Titanium dioxide nanoparticles, Leaching rate
ABSTRAK
Kayu adalah alat yang sangat diperlukan untuk manusia kerana nilai estetiknya, sifat-sifat dan fungsi
ketersediaan. Walau bagaimanapun, kayu akan diuraikan oleh mikrob atau anai-anai. Terdapat banyak kajian
untuk perlindungan kayu dalam aspek ketahanan anai-anai, tahan reput, anti-bakteria, anti-kulat dan larut
lesap kimia. Sebagai contoh, kayu kayu juga dirawat dengan racun hidupan bukan organik (kompleks
berasaskan tembaga dengan krom atau arsenate). Pembebasan mereka boleh menyebabkan pencemaran
kepada alam sekitar. Sebagai alternatif, biosid organik mesra alam (seperti emulsi daripada biosid organik
dan garam tembaga) dan nanomaterial kejuruteraan telah disiasat. Dalam kajian ini, nanopartikel titanium
dioksida disintesis adalah tidak seragam dalam saiz atau bentuk yang tidak teratur dan tidak tersebar dan
purata saiz dialyzed titanium dioksida nanopartikel adalah dalam lingkungan 6 hingga 10 nm. Nanopartikel
titanium dioksida yang dihasilkan telah memasukkan ke dalam Costulata Dyera (Jelutong) blok kayu melalui
penghamilan vakum, keputusan menunjukkan terdapat kadar larut lesap rendah nanopartikel dioksida
titanium terlarut lesap dari blok kayu dalam dua minggu yang dikesan oleh Pasangan Plasma Induktif Optik
Pelepasan Spektrometri.
Kata Kunci: Biosid tak organik, Partikel nano titanium dioksida, Kimia larut lesap
VII
Table of Contents APPROVAL SHEET .............................................................................................................. I
ACKNOWLEDGEMENT .................................................................................................... II
DECLARATION ................................................................................................................. III
LIST OF ABBREVIATIONS ............................................................................................. IV
LIST OF FIGURES AND TABLES .................................................................................... V
ABSTRACT ........................................................................................................................ VI
1.0 INTRODUCTION ........................................................................................................... 1
2.0 LITERATURE REVIEW ................................................................................................ 4
2.1 Titanium Dioxide ......................................................................................................... 4
2.1.1 Differences between Titanium Dioxide Nanoparticles and Titanium .................. 5
Dioxide ................................................................................................................. 5
2.1.2 Benefits of TiO2 as a Pigment and as Nanomaterial ............................................ 5
2.1.3 Structures of Titanium Dioxide Nanoparticles Produced ..................................... 6
2.2 Barriers of Titanium Dioxide in Wood Protection ...................................................... 6
2.3 Alternative Way to Use Metal Oxide Nanoparticles for Inorganic ............................. 7
Biocides Used Nowadays ............................................................................................ 7
2.4 Human Health Concerns with TiO2 ............................................................................. 7
2.5 Synthesis of Titanium Dioxide Nanoparticles ............................................................. 8
2.6 Characterization of Titanium Dioxide Nanoparticles .................................................. 9
2.7 Past, Present and Future of Wood Protection Industry .............................................. 10
2.8 Dyera costulata (Jelutong) Wood Species ................................................................ 11
2.9 Chemical Leaching .................................................................................................... 11
2.10 Penetration of Nanoparticles into the Dry Wood .................................................... 12
2.11 Factors that Influence the Penetration of Nanoparticles .......................................... 12
2.12 Do the Unique Properties of Nanometals affect Leachability or............................. 13
Efficiency against Fungi and Termites? .................................................................. 13
2.13 Does Nanoparticle Activity Depend Upon Size and Crystal Phase?....................... 13
2.14 The Release of Engineered Nanomaterial to the Environment ............................... 14
2.15 Functions of Titanium Dioxide Nanoparticles in Wood Protection ........................ 14
2.16 Acid Digestion ......................................................................................................... 15
2.17 Leaching Rate .......................................................................................................... 15
3.0 MATERIALS AND METHODS .................................................................................. 16
3.1 Preparation of Titanium Dioxide Nanoparticles ........................................................ 16
3.1.1 Sol-gel Process ................................................................................................... 16
3.2 Characterization of Titanium Dioxide Nanoparticles ................................................ 17
3.3 Wood Block Sample .................................................................................................. 18
VIII
3.3.1 Wood Materials and Collection .......................................................................... 18
3.3.2 Wood Materials Sampling .................................................................................. 18
3.3.3 Wood Preservative Treatment ............................................................................ 18
3.3.4 Post Treatment Conditioning .............................................................................. 20
3.4 Chemical Leaching ..................................................................................................... 20
3.5 Acid Digestion ............................................................................................................ 21
4.0 RESULT AND DISCUSSION ...................................................................................... 23
4.1 Preparation and Characterization of Titanium Dioxide Sols ..................................... 23
4.2 Scanning Electron Microscopy (SEM) ...................................................................... 24
4.2.1 Titanium dioxide nanoparticles .......................................................................... 24
4.2.2 Jelutong Wood Sample ....................................................................................... 26
4.3 Transmission Electron Microscopy (TEM) ............................................................... 28
4.4 Fourier Transform Infrared Spectroscopy ................................................................. 30
4.5 UV Spectrophotometer .............................................................................................. 32
4.5.1 Effect of Aging ................................................................................................... 32
4.6 Energy Dispersive X-ray Analysis (EDX) ................................................................ 35
4.7 Treating Results of Retention (Calculation with formulae) ...................................... 37
4.7.1 Comparison of retention (calculation) and chemical analysis (acid digestion) .. 38
4.8 Leach Rate ................................................................................................................. 39
4.9 Analysis Results ........................................................................................................ 41
5.0 CONCLUSION AND RECOMMENDATIONS .......................................................... 44
7.0 APPENDICES ............................................................................................................... 51
1
1.0 INTRODUCTION
From many years ago, wood acts as the main material of furniture, monuments and
decorations which has the close relationship with human. However, fungi play a
considerable role in the deterioration of wood, which contribute a lot in the field of cultural
heritage, as their contamination favors the decay of the materials used for historical art
objects. Fungus prevention, the treatment of wood objects and the conservation work have
been done as restorers. Over the past decade, nanotechnology has been applied in several
fields of cultural heritage conservation, for example the chemical degradation of mural
paintings and paper acidity. Various wood protection applications have been mapped out to
reduce the wood waste and also prolong the life span of a specific wood type. In common,
architectural coatings are used to enhance the durability of wood in exterior environment
(Architectural and Industrial Coatings Solutions, 2012). The architectural coatings usually
used are inorganic UV absorbers since they increase the polymer stability.
On top of that, according to Nanotechnology in the service of wood preservation (n.d.),
wood timber is also being treated with inorganic biocides (copper based complex with
chrome or arsenate). Their release may cause pollution to the environment. As alternatives,
environmentally friendly organic biocide (e.g. emulsion of organic biocides and copper salt)
has been investigated. At the same time, there is also research on wood protection which
focused on process to impregnation metal oxides nanoparticles into wood. Perhaps, the
combination metal oxides nanoparticles and organic biocides have the potential to preserve
the natural colour of the wood and stabilize it against degradation by sunlight, fungi,
moisture, etc.
2
Besides, according to Evans et al. (2008), the scientific community is not giving very
much of interest to this large-scale commercial use of nanotechnology for wood protection
even though there is a lot of contribution in the improvement of wood and other cellulose
materials. The reason might be very few scientists are working in this field and they lack of
experience in the use of metal oxide nanoparticles for wood protection.
The control of particle size, the structure and as well as the morphology of nanoparticles in
synthesize of nanoparticles are very important. There are various numbers of techniques
available to synthesize different types of nanomaterial such as in the form of clusters
powders, colloids, etc. Some important techniques are including, chemical method,
physical method, biological method, as well as hybrid technique (Khan et al., 2011).
However, the common ways to synthesize nanoparticles nowadays are the sol-gel process
and hydrolysis reaction of glycol solution of alkoxide. While in the aspect of
characterization, the techniques commonly used are Fourier Transform Infrared
Spectroscopy (FTIR), UV-Spectrophotometer while the surface morphology is
characterized by Transmission Electron Microscope (TEM) and Scanning Electron
Microscopy (SEM). Inductively Coupled Plasma Optical Emission Spectrometry (ICP-
OES) is also used to determine the concentrations of titanium dioxide nanoparticles that
have leached out to the deionized water.
The problem statement of this study is the use of titanium dioxide nanoparticles could
leach out from the wood and serve as alternative to inorganic biocides (copper based
complex with chrome or arsenate) as wood preservatives since the wood timber treated
with inorganic biocides (copper based complex with chrome or arsenate) causes pollution
to the environment.
3
The objectives of this research project are to synthesize titanium dioxide nanoparticles by
using an appropriate method and to characterize the physical and chemical properties as
well as the morphology of these nanoparticles as well as to determine the chemical
leachability of the wood species of Dyera costulata (Jelutong) which has been impregnated
with titanium dioxide nanoparticles.
2.0 LITERATURE REVIEW
Wood plays important role in our lives since it can be used for furniture and building
purposes. However, wood can be decomposed by fungi or insects especially in tropical and
tropics countries. There were several studies have been done for wood protection
applications. According to Uekawa et al. (2012), nanoparticies, titanium dioxide is applied
to many fields, for example photodynamic therapy, development of photocatalysts and
semiconductors UV -shielding materials, electric devices and solar cells on woven and
knitted fabrics for antibacterial activity.
2.1 Titanium Dioxide
Figure 2.1.3: Structures of Ti02 crystals in the form of: a.) Rutile, b.) Anatase and c.) Brookite (Nolan, 2010)
Titanium is one of the elements that abundantly found on Earth and it is often found in ore
minerals more than in its elemental state (Nolan, 2010). The ore minerals that consist of
titanium are brookite, anatase and perovskite. However, only the first three are main
polymorphs of titanium dioxide (Ti02) that will form different octahedral structures such
as tetragonal and orthorhombic structures as shown in Figure 2.1.3. Titanium dioxide is
chemically and biologically stable, non-toxic, inexpensive and has strong properties of
oxidation (Missler & Tarr, 2011; Shriver & Atkins, 2001; Yun, 2013). Ti02 has the ability
4
5
to show high transparency and photocatalytic activity by cleaning up organohalides found
in ground water and environmentally friendly (Begum and Ahmed, 2008).
2.1.1 Differences between Titanium Dioxide Nanoparticles and Titanium
Dioxide
According to Titanium Dioxide Stewardship Council (2012), compared to titanium dioxide,
titanium dioxide nanoparticles were good protective materials for sunscreens because the
primary particles sizes were small and higher surface area as well as it is transparent. TiO2
was a nanomaterial that is produced with primary particles sizes less than 100 nm and the
manufacturing of various compounds of improved effective was allowed. Besides, it was
not used as a colorant as its function was different from normal titanium dioxide size
particles (Boffetta et al. 2004).
2.1.2 Benefits of TiO2 as a Pigment and as Nanomaterial
Based on Titanium Dioxide Stewardship Council (2006) and Boffetta et al. (2004), TiO2 in
pigment form has the ability of UV light absorbance good in light scattering properties and
white opacity with brightness were required to use in wide variety of applications.
Titanium dioxide in pigment form could conjugate into polymer to protect the system from
degradation. The effects were prolonging the lifespan of the paint and improve the
protection of the solids in paint as well as the coating system. According to Chen &
Fayerweather (1988), as a nanomaterial, TiO2 appears transparent as well as able to
provide UV light absorption which allowed it function in the production of light
stabilization for wood coatings and sunscreens. Environmental pollutants can also be
decomposed via photocatalysis by TiO2 nanoparticles. TiO2 in the form nanomaterial was
used as a DeNOx catalyst support in exhaust gas system in cars, trucks and power plants,
thus minimizes their environmental consequences.
6
2.1.3 Structures of Titanium Dioxide Nanoparticles Produced
There are various structures of titanium dioxide nanoparticles with different properties can
be produced by different solvents such as methanol, ethanol and isopropanol and titanium
tetraisopropoxide acts as a precursor.
Based on Mahyar and Amani-Ghadim (2011), TiO2 nanoparticles prepared in isopropanol
displayed pure anatase crystalline phase with the smaller sizes but had a greater pore
volume and pore size which led to higher photocatalytic activity resulted by nitrogen
physisorption. However, the TiO2 nanoparticles prepared in methanol and ethanol
contained anatase- and rutile-mixed phases with anatase larger crystallite sizes. TiO2
nanoparticles prepared with ethanol had the lowest specific surface area but the greatest
pore volume and pore diameter. The higher photocatalytic activity of the TiO2
nanoparticles prepared in ethanol was attributed to its greater pore volume and pore size as
well as the mixed anatase and rutile crystalline phases.
2.2 Barriers of Titanium Dioxide in Wood Protection
In the aspect of wood protection, based on Jerneja et al. (2011), there was a study
regarding the durability of wood in the external environment can be enhanced by titanium
dioxide as an architectural coatings. However, according to Lu et al. (2003) mentioned
there were two types of limitations in this area. Firstly, TiO2 nanoparticles as catalyst,
especially in anatase, crystal form and reduced rutile form will produce highly reactive free
radicals and exhibit strong oxidizing power when absorbing UV lights, which was
dangerous for photostability of polymer materials. Secondly, by producing suitable nano
composites, the nanoparticles have to be dispersed without agglomeration in organic
binders. The reason was nanoparticles have very high tendency to agglomerate due to their
very large surface area to particle-size ratio. The problem of agglomeration has to be
overcome by many efforts.
a b c
7
2.3 Alternative Way to Use Metal Oxide Nanoparticles for Inorganic
Biocides Used Nowadays
According to Marzbani and Mohammadnia (2014), the use of inorganic biocides such as
Chromated Copper Arsenate (CCA) wood preservatives has been limited in European
countries and United States due to the increasing awareness regarding dangers of using
toxic chemicals in the wood preservation. Previously, there were many variety of inorganic
biocide (Ag and Cu series) used for mold inhibition. Biocides were only effective for
short-term antifungal purposes and toxic. Nowadays, photocatalytic oxidation has been
extensively studied for removing various chemical and biological pollutants (Fujishima
and Honda, 1972). As a commonly used photocatalyst, TiO2 was low mammalian toxic,
non-volatile and environmentally friendly. TiO2 has been proved to be effective for not
only microorganism disinfection, but also volatile organic compounds (VOCs) and odours
or deleterious gases decomposition (Chen et al., 2009).
2.4 Human Health Concerns with TiO2
In the aspect of inhalation, there was a lot of safety and precautions have been taken place
including engineering control and personal protection equipment that have been applied in
workers exposure control and worker risk mitigation as workers at titanium dioxide
engineering plants will be exposed to TiO2 dust (Ramanakumar et al. 2008). The exposure
of TiO2 dust to consumer was assumed to be very small because TiO2 was classically
penetrated into the inner layer of the product was strongly bound such as in plastics or
paints. Thus, inhalation exposure rate to general public is not considered serious. In oral
intake, TiO2 meets appropriate purity standards were approved as a colorant for use in
foods and pharmaceuticals.
According to Monteiro Riviere (2011) in the aspect of skin contact, TiO2 in pigment form
or in nanomaterial form was used as cosmetic applications, such as lipstick, make-up
8
products and sunscreens. Study proved sunscreen containing TiO2 was safe to keep the
skin from dangerous UV radiation. Results showed there is no harmful effects in the
penetration of TiO2 nanoparticles from the sunscreen formulations even the skin was
sunburned (SCCNFP, 2000). The former European Scientific Committee of cosmetic
products and non-food products mentioned that the maximum percentage concentration of
TiO2 is 25 % in order to keep the skin from certain destructive effects of UV radiation. The
former European Scientific Committee on cosmetic products and non-food Products
(SCCNFP) mentioned that the results in maximum concentration of 25% in order to keep
the skin from certain harmful effects of UV radiation.
2.5 Synthesis of Titanium Dioxide Nanoparticles
In the aspect of synthesize of nanoparticles, according to Umme et al. (2011) different
types of nanoparticles in the form of colloids, cluster powders could be synthesis by
various techniques, such as chemical method , physical method, biological method as well
as hybrid technique. Similarly, this was also applied for the structure as well as
morphology as according to Mishra et al. (2008). According to Wang et al. (2008), these
properties were strongly influenced by the synthesis process. Nowadays, preparation of
TiO2 nanopowders was reported by using various methods, including thermal hydrolysis,
precipitation, hydrothermal, solvothermal, chemical vapour deposition and sol–gel process.
Among them, sol–gel process was an effective way to prepare TiO2 nanoparticles since the
nanoparticles formed were pure and homogeneous, as well as large specific surface area
(Wang et. al, 2008). Based on Yu et al. (2003), performance of sol-gel process which was
considerably depends on the process conditions such as pH, water/alkoxide ratio, type of
precursors and reagents, calcination temperatures, reaction and mixing conditions have
been reported by researches. Based on Maurizio et al. 2005, TiO2 nanoparticles produced
by this method were amorphous in nature. Preparation of titanium dioxide nanoparticles by
9
sol gel process was generally used, due to its low cost equipment and low temperature
required.
On the other hand, in hydrolysis reaction, the samples derived from TiCl4 were very
photoactive and the process was not involving filtration and calcination in order to obtain
highly efficient anatase phase. The structure of obtained titanium dioxide nanoparticles
formed was affected by the concentration of NH3 aqueous solution (Uekawa et al., 2012).
According to Maurizio et al. (2005), the obtained sol was very stable without
agglomeration of particles or gels as TiCl4 will not lead to the formation of impurities in
the final product. The titanium dioxide nanoparticles obtained showed an enhanced
adsorption towards the cationic dye molecules (Zaki et al., 2010).
In the aspect of hydrothermal method, the hydrothermal method was different from sol gel
process in the aspect of crystallite size, crystallinity, band gap, structural properties. TiO2
nanoparticles prepared via sol-gel process exhibit high luminescence than hydrothermal
derived nanoparticles due to the chemical instability during fabrication process. In sol gel
process, the TiO2 nanoparticles produced were highly crystalline and had smaller
crystallite size as compared to the one prepared by hydrothermal method (~ 17 nm). The
band gap of the synthesized nanoparticles was found to be size dependent.
2.6 Characterization of Titanium Dioxide Nanoparticles
Based on the research from Alem et al. (2009) titanium dioxide nanoparticles was an n-
type oxide semiconductor that exhibit photoconductivity and photocatalytic activity in UV-
shielding materials, solar cells, and electric devices. Titanium dioxide nanoparticles were
high wettability or superhydrophilicity. These properties can be applied in mirrors, since
mirrors with coating nao-TiO2 consists of antifogging function. Therefore, various glass
10
products such as mirrors and eyeglasses now can be imparted with antifogging properties
by using this technology, with low cost processing fees (Fujishima et al., 2002).
According to Fujishima et al. (2000), the environmental contaminants will be decomposed
by TiO2 nanoparticles as a photo catalyst. Nano-TiO2 particles were high photocatalytic
efficiency, biological and chemical inertness with tremendous UV resistance, low cost,
favourable mechanic chemical properties and stability against photo corrosion. Purification
of wastewater can be developed by TiO2 nanoparticles based on photocatalytic processes
as organic compounds can be broken down by photocatalytic process. For example, if one
put catalytically active nano-TiO2 powder into a contaminated water and allows it to be
exposed to the sunlight, the water will be slowly purified. Besides, self-cleaning window
glass and self-cleaning paint was containing titanium dioxide nanoparticles have been
developed (Fujishima & Zhang, 2006).
2.7 Past, Present and Future of Wood Protection Industry
Wood was an indispensable tool for our human and it has been history for our mankind. In
our grandmother generation, wood has been used for cooking and building their house,
even nowadays, the market demand for the wood is very high. Wood was used frequently
for external building applications during the industrial technology advanced especially for
the period of Industrial Revolution. However, wood does not inherit decay resistance
properties due to the biological attack, such as termites, fungi and bacteria. According to
Hunt and Garratt (1967), many processes have used to treat wood in the past, such as
Oscillating Pressure Method (OPM), rapid cyclical oscillation between vacuum and
pressure was employed to treat refractory wood species in Australia. Based on Freeman et
al, 2003, Alternating Pressure Method (APM), was also established to treat green or partly
seasoned wood with Chromated Copper Arsenate (CCA).
11
Presently, vapour phase boron treatments function as main treatments for wood and wood
based materials (Murphy et al. 2002). The main benefits of the method were reckless and
hygiene of treatment and able to dry, handling and conditioning in a single vessel.
In future, wood will be protected by Engineered Wood Composites (EWC). According to
Vlosky and Shupe (2002), the influence of the biocide on the chemical interaction with the
resin , the physical properties of the compound, the dissemination of biocide within the
product, the effectiveness of the treated composite, and the result of manufacturing on
EWC properties have to be considered by using the combination of biocide and EWC.
Effects of moisture and moisture temperature altered have to be minimized in the aspect of
dimensional stability by modifying wood properties.
2.8 Dyera costulata (Jelutong) Wood Species
According to Meding et al. (1996), Jelutong, Dyera costulata was a type of wood growing
in South-East Asia. It was soft and easy to work and was used in, e.g., model workshops in
car factories. It has also been much used in woodwork teaching in Swedish comprehensive
schools but its wood dust causes contact allergy, as a result, the school was recommended
to use a safer wood species as an alternatives for teaching.
2.9 Chemical Leaching
Previously, chemical leaching was used to test the leaching concentrations of Chromated
Copper Arsenate (CCA) wood preservatives since this inorganic biocide impregnated into
the wood will pollute the environment. According to Weis et al. (1998), studies have been
conducted to expose marine organisms to Chromated Copper Arsenate (CCA) treated
wood or leachate waters. The results have shown against a range of aquatic organisms.
According to Desch and Dinwoodie (1996), one of the major problems was lacking of
understanding of long-term leaching rates, so the recommended preservative loading was
12
presently set at very high levels. There were factors to influence the leaching of chromium,
copper and arsenic from disposed Chromated Copper Arsenate (CCA) treated wood, such
as pH of the leachate, temperature, duration of the leaching and types of leaching agent
(Moghaddam and Mulligan, 2008).
2.10 Penetration of Nanoparticles into the Dry Wood
There was different effectiveness in various impregnation methods used. Firstly, the
capillary pressure technology was the basis of the liquid flow through the wood was
spraying, brushing, infusion and dipping under the atmospheric pressure. Secondly, the
flow of liquids through the wood structure will be accelerated by the technologies where
created pressure gradient such as vacuum-pressure, vacuum and pressure impregnation
(Johnson & Kamke, 1992).
2.11 Factors that Influence the Penetration of Nanoparticles
The wood absorptivity to liquids, the penetration methods and physiochemical properties
of specific types of nanoparticles were dependent on the actual impregnation of
nanoparticles. The penetration of nanoparticles was influenced by its viscosity which was
related to the relative molecular weight of the nanoparticles (the size of its molecules) and
the concentration of its solution. The constant viscosity of the nanoparticles and the
increased of the molecular weight of the nanoparticles decreased the penetration of
nanoparticles. In fact of impregnation based on the polarity, capillary action as well as its
wetting ability influences the penetration of nanoparticles. An appropriate impregnation
method must be chosen in correspondence with the degree of decomposition of a given
wooden object. Therefore, a compromise between the molecular weight of the
nanoparticles, the concentration and the viscosity of the solution and the solvent used have
to been concerned to ensure nanoparticles penetrate into the damage wood (Drncova &
Studium, 2011).
13
2.12 Do the Unique Properties of Nanometals affect Leachability or
Efficiency against Fungi and Termites?
According to Siegel (1999), due to the nanoparticles structure in the size range of 1-100nm,
nanotechnology has developed in many applications, such as devices, materials or system.
According to Clausen (2007), nanometal preparations were able to improve their
performance in wood protection. Firstly, nanometals were created in a controlled particles
size. Secondly, nanoparticles can be performed in high dispersion stability. Finally,
nanometals preparations have a low viscosity. In conclude, due to these properties present,
particles distribution was more uniform for greater penetration and protection over the
wood surface. According to Kartal (2009), termite feeding was inhibited by nano-zinc and
the study shows the evaluation of nanometals generally inhibit the white-rot fungus and
were approximately will be effective in inhibiting the brown-rot test fungi.
2.13 Does Nanoparticle Activity Depend Upon Size and Crystal Phase?
Various studies to establish the biological activity as well as the impact of physiochemical
parameters such as crystal phase, size-surface properties and the others. For instance, the
influence of size of the nanoparticles on biological activity, the mass of the sample on
biological response and this should be done in toxicological studies and comparisons of the
effects of different sizes of particles. According to Warheit et al. (2006), they have been
several studies on the toxicity evaluation of nanosized titanium dioxide and a relationship
to physico-chemical characteristics is established. For instance, three sizes of titanium
dioxide nanoparticles were dosed by Warheit and co-workers to the lungs of rats and the
results showed toxicity was independent upon particle size or surface area (Warheit et al.,
2006). However, anatase/rutile mixtures was the lowest oxidant reactivity presented by
TiO2 particles with similar size but different crystal morphology, followed by pure anatase,
and highest was amorphous samples (Jiang et al., 2008).
14
2.14 The Release of Engineered Nanomaterial to the Environment
There are many impressive application prospects of nano-sized materials in various
applications and our daily products and as a result, production of nanomaterial has been
significantly increased (Royal Commission Report, 2008). However, potential impacts on
human and environment of such material will be given a lot of attentions. According to
Gottschalk (2011), nanomaterial could be emitted to three categories, which are free
nanomaterial, aggregated nanomaterial or lastly is impregnated in a matrix. A previous
study has proofed evidence for the release of nanomaterial into the environment from
products containing nanomaterial. Results showed the nanomaterial are actually released
but the quantifying what has been released is the main difficulties. Therefore, the
composition within the products may be altered, but most importantly is the nanomaterial
is still embedded in the matrix and not released as an individual particle.
2.15 Functions of Titanium Dioxide Nanoparticles in Wood Protection
The UV transmission radiation can be absorbed by nano-titanium dioxide and its
photocatalytic properties provide antibacterial coatings (Daoud et al, 2005). The antifungal
properties of titanium dioxide by using Aspergilus Niger fungal cultivation and UV
irradiation have been studied by Chen et al. (2009). Results showed that the TiO2 coated
film in the presence of UVA (365nm) radiation exhibited antifungal capability. Saha et al.
(2001) used nano- TiO2 to coat the surface against UV radiations. The result showed that
there were no significant influences on wood colour when the titania embedded with UV
absorber coating has applied but the adding of lignin stabilizer plays an significant role in
protection of wood against UV exposure. According to Shabir et al. (2013), titanium
dioxide nanoparticles exhibited decay resistance and this was affected by the amount of
titanium dioxide present in the wood structure. The result was showing the wood treated
15
with low concentration titanium dioxide solution was more decay resistant that the wood
treated with higher concentrations.
2.16 Acid Digestion
According to Ghanthimathi et al. (2013), acid digestion was used to transformed solid
samples such as sawdust into liquid phase and undergoes digestion whereby the organic
components are destroyed by acid releasing metals that were dissolved into solution that
can be analyzed spectroscopically.
There are various types of acid digestion, such as microwave assisted acid digestion. In the
investigation of Soylak et al. (2004), microwave assisted acid digestion procedures are
gaining popularity recently due to the speed of the digestion process as well as less
possibility of contamination during the process.
Microwave digestion procedures has the advantages of short digestion time, less acid
consumption and high extraction efficiencies in making them preferable when compared
with the conventional methods (Ghanthimathi et al. , 2013) .
2.17 Leaching Rate
According to Lebow (1996), there were various factors to influence leaching rate, such as
exposure time, surface area, wood species and preservatives components. For wood species,
there was high leaching rate for a more permeable wood because of the rapid movement of
leachate. However, Kennedy and Palmer (1994) also noted that the leaching of CCA may
be greater from heartwood than sapwood because heartwood extractive restrict with the
fixation process.
16
3.0 MATERIALS AND METHODS
3.1 Preparation of Titanium Dioxide Nanoparticles
3.1.1 Sol-gel Process
Stable TiO2 colloidal suspension will be prepared based on methods that are reported by
Firdaus (2013), Ling (2007) and Xu and Anderson (1994) with some modifications. 1.3
mL of concentrated HNO3 will be first mixed with 180 mL of deionized water at room
temperature. The diluted solution will be stirred vigorously before slowly adding 15 mL of
titanium isopropoxide (TTIP) into the solution using a micropipette. Since TTIP could not
allow to be oxidized for a longer period, the addition of TTIP will be done immediately to
form small precipitates. It will be further stirred vigorously for 30 minutes and left to be
peptized for 4 days before performing the dialysis method.
To prepare dialysis, a dialysis tube with 20 cm length will be first submerged in the wash
solution containing deionized water for 30 minutes. It is then filled with TiO2 sols before
immersing it into 2.0 L of deionized water in a 2.0 L beaker and magnet-stirred vigorously
for 3 days to obtain purified TiO2 sol.
For this process, concentrated nitric acid (HNO3) played important roles as a catalyst and a
ligand to modify the process of hydrolysis and condensation of titanium alkoxide
according to the equations (4) to (6) (Senain et al., 2011):
Ti (OR) 4 + H2O → Ti (OR) 3(OH) + ROH --------------------------- (4)
Ti (OR) 4 + Ti (OR)3(OH) → Ti2O(OR)6 + ROH -------------------- (5)
Ti (OR) 4 + 2H2O → TiO2 + 4ROH ----------------------------------- (6)
17
3.2 Characterization of Titanium Dioxide Nanoparticles
After TiO2 nanoparticles formed, it will be characterized by the following instruments as
follows:
a. Fourier Transform Infrared Spectroscopy (FTIR) to examine the chemical bonds
and stretching modes as well as to ascertain the purity in the range of 500cm-1
-
4000cm-1
within titanium dioxide nanoparticles
b. UV Visible Spectroscopy (UV-Vis) to study the aggregation and stability of titanium
dioxide colloidal suspension as well as the presence of Ti=O double bond in the
wavelength range of 200cm-1
to 600cm-1
c. Scanning Electron Microscopy (SEM) to determine the surface morphology and the
size distribution of the nanoparticles
d. Transmission Electron Microscope (TEM) to determine the shape and the size of
TiO2 nanoparticles with higher resolution
e. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) to
determine initial concentration of TiO2 nanoparticles before chemical leaching and
after chemical leaching from leachate of Dyera costulata (Jelutong)
1.3mL of HNO3 + 180mL
of deionized water
Transparent, bluish TiO2 sol
Purified TiO2 sol
Figure 3.1.1: Flow chart of the steps involved in preparation of TiO2 nanoparticles via sol-gel process (Xu and
Anderson, 1994)
15mL of TTIP
Peptize for 4 days by vigorous
stirring at room temperature
Dialysis until pH 3.5
18
f. Energy Dispersive X-ray to study for the elemental analysis within the wood blocks
before and after impregnation of titanium dioxide nanoparticles
3.3 Wood Block Sample
3.3.1 Wood Materials and Collection
Wood blocks (each 40mm × 20mm × 5mm) from Dyera costulata (Jelutong) were used for
E11-06 standard method of determining leachability of wood preservatives from American
Wood Protection Association Standard.
3.3.2 Wood Materials Sampling
Before Chemical Leaching
Well oven dried wood samples, Dyera costulata (Jelutong) measuring 40mm × 20mm ×
5mm for laboratory leaching test was produced. The wood samples were end-grain-sealed
with a layer of glue to prevent TiO2 nanoparticles penetration or leaching. The weights of
the wood blocks before and after sealing with a layer of glue were taken. The wood
samples were then conditioned at 105oC for 48 hours and weighed immediately.
3.3.3 Wood Preservative Treatment
Replicated wood samples as well as the control wood samples of Dyera costulata (Jelutong)
were impregnated with TiO2 nanoparticles by vacuum impregnation. Based on AWPA
(American Wood Protection Association Standards), 2007), the wood blocks were placed
in a suitable beaker to be treated for each retention group and weight them down to prevent
eventual floating during treatment. The beakers were placed in the desiccator of the
impregnation apparatus directly below the outlet from the treating solution flask. The
apparatus was attached to the vacuum and reduce the pressure in the treating chamber to
13.3 kPa (3.94 in. of mercury absolute) or less for at least 30 minutes. After 30 minutes
vacuum period, the acess to the treating solution flask was opened so that the treating
19
solution flows into the bottom of the beaker and covers the test blocks. When the vacuum
was released, the beakers were removed from the treating chamber and cover with plastic
film to minimize evaporation. The blocks were leaved to submerged for at least 1 hour.
After the treatment, each wood blocks were individually removed from the solution and
wipe lightly to remove surface solution and weighed immediately. The retention of each
block is then calculated by using formulae below.
Retention, kg/m3 =
G=T2-T1, the weigh in grams of the treating solution absorbed by the
Block
C= Grams of preservatives in 100 grams of treating solution
V= Volume of the block in ml
Place the wood blocks in a suitable beaker to be treated and weight
them down to prevent floating
Place the beakers in the desiccator of the impregnation apparatus
which was attached to the vacuum and reduce the pressure in treating
chamber to 13.3 kPa for at least 30 minutes
Remove the beakers from the treating chamber, cover with plastic
film and left them to submerge for at least 1 hour after the releasing
the vacuum
Remove each wood samples from the solution and wipes lightly to
remove surface solution and weigh them immediately after the
treatment. Calculate the retention of the wood samples.
Figure 3.3.3: Summary of Wood Preservative Treatment by Vacuum Impregnation
20
3.3.4 Post Treatment Conditioning
After the wood blocks were impregnated and weighed, an environment suitable for fixation
of the TiO2 nanoparticles and subsequent drying was provided. After that, the blocks were
dried by spacing them on trays or racks at room temperature in a manner to avoid
formation of surface deposits. After drying, the blocks were placed in a conditioning room
for 21 days (AWPA, 2007).
3.5 Chemical Leaching
Based on AWPA (2007), the leaching apparatus was set up for each retention group. The
replicated wood samples which have been impregnated were placed in the leaching flask.
The leaching flask was filled with 100 ml of deionized water and the wood samples were
completely submerged by glass slides. The leaching flask was coved by a suitable stopper
or lid to prevent evaporation of the leachate. After that, the leaching flask was placed on
the magnetic stir bar. The temperature at 22oC – 28
oC was maintained. The leachate were
collected in a bottle after 6 hours, 24 hours, 48 hours, 96 hours, 144 hours ,192 hours ,240
hours, 288 hours , 336 hours and an equal amount of fresh deionized water were replaced.
After chemical leaching, the treating results and leach rate were tabulated and interpreted.
Dry the wood blocks by spacing them on trays at room
temperature
Place the wood blocks in a conditioning room for 21 days
Figure 3.3.4: Summary of Post Treatment Conditioning
21
3.6 Acid Digestion
After Chemical Leaching
After chemical leaching, the wood blocks were placed on trays or racks at room
temperature for acid digestion. According to AWPA (2013), the sawdust of each wood
block was weighed accurately in 0.5 g and poured into 250 ml conical flask with three
glass beads. Each wood block has three replicates. A digestion blank was prepared along
with the samples. 15 ml of 65% nitric acid was measured and added into the 250 ml
conical flask and the hot plate was warmed slowly. The heat was increased after initial
reactions of brown fumes subside and then the solution was heated until it turned into clear
solution. The heat was reduced and 5 ml of 30% hydrogen peroxide was added dropwise.
If the solution was not clear after this treatment, the heat was increased and another 5 ml of
30% hydrogen peroxide was added. However, the digestion solution should never be
allowed to boil down to dryness to prevent the possibility of explosion. After acid
digestion, the percent of chemical leached can be determined by using the formula below:
Percent chemical leached =
A= Total weight of components in leachate (mg)
B= Total weight of components in leached blocks (mg)
Place the impregnated replicate wood samples within the leaching flasks
Measure and add 100 ml of deionized water into the leaching flasks and
completely submerged the wood samples
Place the leaching flask on the magnetic stir bar, collect and replace the deionized
water after 6 hours, 24 hours, 48 hours, 96 hours, 144 hours ,192 hours ,240 hours,
288 hours , 336 hours
Figure 3.3.5: Summary of Chemical Leaching
At temperature 22oC – 28
oC
22
Weigh the sawdust of each wood block in 0.5g and add into the 250 ml of conical flask
Measure 15 ml of 65% nitric acid and add into the 250 ml conical flask and warm the hot
plate slowly
Heat was increased after initial reactions
of brown fumes subside and then heated
until it turned into clear solution
Reduce the heat and add 5 ml of 30% hydrogen peroxide dropwise
If the solution was not clear after this treatment, increases the heat and add another 5 ml of
30% hydrogen peroxide
Figure 3.3.6: Summary of Acid digestion
4.0 RESULT AND DISCUSSION
4.1 Preparation and Characteriz ation of Titanium Dioxide Sols
The preparation of titanium dioxide colloidal suspension by the sol-gel process was an
easy and straight forward method, but it was time-consuming since the peptization and
dialysis process have taken up to 5 days in order to obtain a transparent and bluish Ti02
sol. Before the colloidal suspension (sol) was peptized, its aqueous-based texture was
opaque and milky. The sol became slightly bluish and transparent after the process of
peptization as shown in Figure 4.1(a) and (b). The Ti02 sol prepared by the sol-gel process
was in liquid state and was found to be very stable as there was no precipitate formed even
after aging for several months. According to Ling (2007), the titanium dioxide sol prepared
by the hydrolysis method was not very stable and easier to react with water if ethanol was
used as the solvent.
b
• Figure 4.1: Ca) Peptization process taken place for 4 days
Cb) (I) Transparent and bluish Ti02 sol after 4 days (II) Gel-like Ti02 sol after dialysis
23
4.2 Scanning Electron Microscopy (SEM) 4.2.1 Titanium Dioxide Nanoparticles
Figure 4.2.1: SEM micrographs of Ti02 nanoparticles from Ti02 sols at various magnifications (a, b) Non-dialyzed, (c, d) Dialyzed sol and (e, f) Commercial titanium dioxide powder
24
25
TiO2 nanoparticles synthesized by the sol-gel process were analyzed by SEM to investigate
their surface morphology and microstructure. The SEM micrographs were taken at various
magnifications.
Figure 4.2.1 (a, b, c, d) reveals that titanium dioxide nanoparticles were non-uniform in
sizes or irregular shapes and were not well-dispersed. TiO2 nanoparticles were observed to
form small agglomerates consisting of many tiny nanoparticles.
At the level of 20 000 × magnification, individual TiO2 nanoparticles were not resolved or
discernible. The nanoparticles shown in Figure 4.2.1 (a, b, c, d) were obviously
agglomerated since the nanoparticles were not undergoing calcination reaction reported by
Hussain et al. (2010). Titanium dioxide nanoparticles showed fine TiO2 nanoparticles of
10–20nm range and the sample was calcined at a temperature of 400 ◦
C for 3 h, TiO2
nanoparticles were mostly in the dispersed phase and few formed aggregates.
Figure 4.2.1 (a, b, c, d) reveals no much difference in the surface morphology of TiO2
nanoparticles between non-dialyzed and dialyzed samples. However, there was obvious
that both non-dialyzed and dialyzed samples have indefinite shape and rough surface.
Based on Martinez-Gutierrez et al. (2010), the morphology of the TiO2 nanoparticles
would be influenced by the method of preparation. TiO2 nanoparticles prepared via sol-gel
process were highly crystalline, more agglomerated and had smaller crystallite size as
compared to TiO2 nanoparticles prepared by the hydrothermal method (Vijayalakshmi &
Rajendran, 2012).
Figure 4.2.1 (e, f) shows the size and morphology of commercial titanium dioxide
nanoparticles powder. The size of commercial titanium dioxide nanoparticles were more
unifonnly distributed and of larger mean particies sizes than Ti O2 nanoparticies prepared
in the present study.
4.2.2 Jelutong Wood Sample
Figure 4.2.2: SEM micrographs of wood sample. Jelutong Ca. b) Cross Section C c. d) Radial section C e. f) tangential section before and after titanium dioxide nanoparticles impregnated
Ca. c. e) Untreated Wood. (b. d. f) Treated Wood
26
27
Figure 4.2.2 shows the SEM micrographs of untreated wood samples and treated wood
samples. For untreated wood, the cell wall, the pit, parenchyma and tracheid were seen
(black arrows pointing to pit and cell wall) as shown in Figure 4.2.2 (a, c, e). The structure
elements of Jelutong wood were vessel, fiber, parenchyma and ray (Figure 4.2.2).
Parenchyma is well developed around the vessel. The cell wall of parenchyma was thinner
than that of fiber (Devi et al., 2013).
The SEM micrographs of the treated wood samples were shown in Figure 4.2.2 (b, d, f).
There was a layer of gel-like liquid were seen in Figure 4.2.2 (b, d, f) as indicated by the
black arrows in the micrographs. The nanoparticles were not uniformly distributed and
aggregates of TiO2 nanoparticles were observed due to the moisture pressure as a barrier
against proper impregnation (Younes and Pouya, 2015). However, not many of the
titanium dioxide nanoparticles were seen in Figure 4.2.2 (b, d, f) since TiO2 nanoparticles
could not be resolved at this level of magnification. Most of the layers of gel-like liquid
were present on cell wall adjacent to tracheid and rays.
According to Mahr et al. (2013), thicker layer of solids caused cracks and defects in titania
gel protection layers whereas thinner layers led to more uniform coating on the cell wall.
Therefore, the wood crystalline structure were observed to be disorganized in Figure 4.2.2
(b, d, f) as compared to Figure 4.2.2 (a, c, e), which is the untreated wood due to the
cracking or defects of the thicker layer of solids in titania gel layers.
b
c (e)
D
Tracheid
4.3 Transmission Electron Microscopy (TEM)
Figure 4.3: TEMrnicrographs of TiOz nanoparticles from TiOz sols at various magnifications Ca, c) Non-dialyzed and (b, d) Dialyzed sol
TEM was used to further examine the size, shape and morphology of Ti02 samples. TEM
gave the size and shape of the particies ciearly even in higher magnifications. Figure 4.3
shows the TEM image of titanium dioxide nanoparticies prepared by the sol-gel process. It
was observed that the mean sizes of the nanoparticies for dialyzed sols were 7.63 nm ±
0.023 and between the range of 6 nm to 10 nm. The titanium dioxide nanoparticies
prepared were in anatase phase since most of them have spherical morphology.
Titanium dioxide nanoparticies as shown in Figures 4 (c, d) were mostly of spherical
morphology. According to EI-Sherbiny et al. (2014), most of anatase phase Ti02
28
29
nanoparticles were of spherical morphology whereas most of rutile phase TiO2
nanoparticles were needle-like morphology.
Besides, as reported by Vijayalakshmi & Rajendran (2012), most nanoparticles prepared
through the sol-gel process were adhering to each other easily to form agglomeration of
nanoparticles as shown in Figures 4.3 (a, b, c). Figure 4.3 (c) and Figure 4.3 (d) show the
aggregated titanium dioxide nanoparticles and dispersed titanium dioxide nanoparticles at
the same level of magnification respectively.
Titanium dioxide nanoparticles of non-dialyzed and dialyzed sols (Figure 4.3) exhibited
different morphology. Figures 4.3 (b, d) show more dispersed titanium dioxide
nanoparticles as compared to Figures 4.3 (a, c).
Figures 4.3 (a, c) consist of larger agglomerates since it contains more unreacted reactant
and impurities as no dialysis process taken place. Figures 4.3 (b, d) give a clearer image
and less agglomerates shown since it undergoes dialysis to get rid of the impurities and
unreacted reactant.
30
4.4 Fourier Transform Infrared Spectroscopy
Figure 4.4: FT-IR spectra of different titanium dioxide nanoparticle samples
(a) Non-dialyzed and (b) Dialyzed
(a)
(b)
31
FTIR spectra of the titanium dioxide nanoparticles from non-dialyzed and dialyzed sol
samples are shown in Figure 4.4. No significant differences between the dialyzed and non-
dialyzed titanium dioxide nanoparticles could be observed, except for the peak intensity of
the characteristic peaks. The broad peaks at 3356 cm-1
and 3293 cm-1
observed were
signature of hydroxyl group in both non-dialyzed and dialyzed sample respectively as
shown in Figure 4.4 (a, b). In anatase sample, a broad band in the range of 3,600–3,200
cm-1
was observed which was related to the stretching hydroxyl group (O–H), representing
the presence of surface water as moisture. According to El-sherbiny (2014), the other peak
located at 1,635cm-1
was attributed to titanium carboxylate, which might be originated
from TTIP precursor and ethanol. The presence of such peak might be due to incomplete
washing process of the prepared powders. Table 4.4 shows the characteristics FTIR
absorption peaks of titanium dioxide nanoparticles samples.
However, the differences in the intensity of the peak were substantial, especially the
intensity of C-H stretching peak. The intensity of C-H peak in non-dialyzed was stronger
than in dialyzed titanium dioxide nanoparticle sample. This was because some of the
impurities or unreacted reactants were eliminated through the dialysis process. Therefore,
the intensity of C-H peak was lower in the dialyzed titanium dioxide nanoparticle sample
as compared to the non-dialyzed titanium dioxide nanoparticle sample.
No. Absorption Peaks (cm
-1)
Functional Group Non-dialyzed Sol Dialyzed Sol
1. 3356 3293 O-H
2. 1383 1384 C-H
Table 4.4: FT-IR absorption peaks of TiO2 nanoparticles samples
32
0
1
2
3
4
5
6
7
8
200 250 300 350 400 450 500 550 600
AB
S
Wavelength (nm)
Freshly prepared
Week 1
Week 2
0
1
2
3
4
5
6
7
8
200 250 300 350 400 450 500 550 600
AB
S
Wavelength (nm)
Freshly Prepared
Week 1
Week 2
4.5 UV Spectrophotometer
4.5.1 Effect of Aging 4.5.1.1Non-dialyzed Sample
4.5.1.2 Dialyzed Sample
Figure 4.5.1.1: Scanning UV spectra of non-dialyzed TiO2 sol prepared by the sol-gel process at various aging time
Figure 4.5.1.2: Scanning UV spectra of dialyzed TiO2 sol prepared by the sol-gel process at various aging time
33
As shown in Figures 4.5.1.1 and 4.5.1.2, the wavelength (λmax) and intensity of the major
absorption peaks (Amax) were examined as a function of aging time at room temperature.
The wavelengths of absorption peaks (λmax) in Figure 4.5.1.1 and 4.5.1.2 were observed
in the wavelength range of 350nm to 400 nm and 350nm to 450nm respectively. As the
aging duration was increased, there was a gradual reduction of absorbance. The λmax
obtained agreed with the adsorption spectrum of colloidal TiO2 sols at a wavelength
around 350nm as reported by Yu et al. (2000).
The absorbance of both non-dialyzed and dialyzed colloidal TiO2 sols decreased
(hypochromic effect) due to agglomeration of titanium dioxide nanoparticles, which could
then settled down and caused the concentration of nanoparticles present in the sol to be
reduced as the aggregation of sedimentation was decreased. The dispersion stability of
nanoparticles in titanium dioxide colloidal suspension was decreased (Sharif et al., 2009;
Sharif et al., 2011).
According to Adan et al. (2007), the steep increase of the adsorption at wavelength lower
than 380 nm could be assigned to intrinsic band gap adsorption of pure anatase TiO2.
Therefore, the steep increases down of the adsorption peaks at a wavelength from 300 nm
to 350 nm , from 300 nm to 360 nm in the UV-Vis spectra of Figure 4.5.1.1 and 4.5.1.2
respectively indicate the presence of anatase TiO2 nanoparticles.
The UV-spectra reveals that dialyzed titanium dioxide nanoparticles (Figure 4.5.1.2)
showed the narrow peak at wavelength of 350 nm which indicated that high refractive
index and high brightness (El-Sherbiny et al., 2014). According to Isley & Penn (2006),
dialyzed titanium dioxide nanoparticles showed substantially less conversion from brookite
34
to anatase (higher brookite contents) compared to those samples that were not dialyzed.
Particles in the colloidal suspensions that were not dialyzed were expected to be easier
agglomerated than those in the dialyzed suspensions because dialysis removed the side
products of sol-gel synthesis and, thus, substantially reduce the ionic strength.
Figure 4.5.1.3 shows that the λ max of non-dialyzed and dialyzed titanium dioxide
nanoparticles for freshly prepared, first week and second week. For non-dialyzed titanium
dioxide colloidal suspension, the λmax increases and shift to the right (red shift). A red
shift in UV –Vis Spectrum of titanium dioxide nanoparticles was an indicative of
increasing nanoparticles size (Naser Hatef et al, 2012). According to Paulauskas et al.
(2013), a red-shift was observed in the absorption range of the titanium dioxide colloidal
suspension has been reported that an indicative of the presence of the rutile phase within
the suspension. Besides, red spectral shifts shown in Figure 4.5.1.3 can be indicated to
show the TiO2 nanoparticles have enhanced photocatalytic activity (Song et al., 2008).
330
340
350
360
370
380
390
400
410
420
430
Freshly prepared First Week Second Week
ƛm
ax
Non-dialyzed
Dialyzed
Figure 4.5.1.3: λmax of Non-dialyzed and dialyzed titanium dioxide nanoparticles for freshly prepared,
first week and second week
However, there are no changes in the A max of dialyzed titanium dioxide sol in Figure
4.5.l.3, which indicated the dialyzed titanium sol was more stable if compared to non-
dialyzed sol. This is because an aqueous titanium dioxide sol was more stable in a neutral
pH range and this was obtained by removing the acidic substance by dialysis (Yamada et
aI., 1999).
1000 4.6 Dispersive X-ray Analysis (EDX) 900
800
700 Element Atom(%) 600 Carbon 60.01
m ro § 500 c.: 0 0 u
Oxygen 38.79 Silica 0.43
400 Calcium 0.77
300
200 ~ ~~ O'i P Ka U U
100 I I
0
0.00 l.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
keY
Figure 4.6.1: Energy dispersive X-ray element analysis of untreated wood
800 Element Atom(%)
700 Carbon 45.87 600 Oxygen 30.49
~ 500 Titanium 23.14 u Silica 0.30
400 Calcium 0.20
300
200 ro.o ro
~~ "" ~ uu ~ ~
100 I I
0
0.00 l.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
keY
35
36
Figure 4.6.1 and Figure 4.6.2 show the elemental composition in the untreated and treated
wood which analyzed by EDX analysis. The presence of significant peaks for Ti, O, C and
Si, as shown in Figure 4.6.2, suggested the successful impregnation of titanium dioxide
nanoparticles into wood through the vacuum impregnation processes (Devi et al. 2013).
Figure 4.6.1 and Figure 4.6.2 show the presence of carbon in high percentage in the EDX
analysis of the untreated and treated wood samples was ascribable to hydrophobic bonds
such as hydrogen present in lignin and fatty acids as well as due to hemiacetal carbon of
cellulose and hemicellulose (Saha et al., 2011). Besides, the oxygen shown in the EDX
analysis of untreated and treated wood was attributed to the oxygen elements in cellulose,
such as benzyl aryl ether and diaryl ether in the wood. The wood samples were also
consists of tiny amounts of other elements, such as silica, calcium and phosphorus.
Figure 4.6.2: Energy dispersive X-ray element analysis of treated wood
37
4.7 Treating Results of Retention (Calculation with formulae)
* Refers Table A in Appendices
*Parentheses refers to standard deviations
Wood Blocks Retention, kg/m3 Retention , mg Mean
Control Wood 0 0 0
Wood prior to leaching 1
Wood prior to leaching 2
Wood prior to leaching 3
5.3720
3.9660
5.2693
21.49
15.86
21.08
19.48 (2.56)
* (Refers Table A in Appendices) *Parentheses refers to standard deviations
Table 4.7 (a) and (b) show the individual component retention of titanium and titanium
dioxide nanoparticles in leached wood blocks. According to Lebow (2001), CCA treatment
retention that applied to wood was common in 5.4 kg/m3. Therefore, the results showed in
Table 4.7 different only slightly if compared to the data mentioned in CCA treatment.
Several researches have reported the percentage of leachable components decreased with a
decreased retention levels (Lee et. al 1993; Wood et. al 1980; Lebow, 2001).
On the other hand, previous studies have suggested that higher retention levels provide
more water repellency to the wood, thus lowering the leaching rate (Coetze, 1980). The
results of retention on leaching of chemical components were not clear. Increased retention
has been reported for both increase (Irvine et al. 1972) and decrease (Lee et al. 1993;
Wood et al. 1980) in the percentages of leached components.
Besides, the moisture content of the wood could influence the retention levels and distribution
of TiO2 nanoparticles of the leached wood blocks. The percentage of moisture content of the
Wood Blocks Retention, kg/m3 Retention , mg Mean
Control Wood 0 0 0
Wood prior to leaching 1
Wood prior to leaching 2
Wood prior to leaching 3
8.9714
6.6232
8.8000
35.89
26.49
35.20
32.53 (4.28)
Table 4.7 (a): Individual retention of TiO2 nanopartcles for the wood blocks before chemical leaching
Table 4.7 (b): Individual retention of Ti nanopartcles for the wood blocks before chemical leaching
38
leached wood blocks was shown in Table A in Appendices. On top of that, there were several
factors which influence the retention levels of chemicals, such as impregnation method, wood
structures and wood preparation method (Younes & Pouya,2015).
4.7.1 Comparison of retention (calculation) and chemical analysis (acid digestion)
*Refers Table A in Appendices
*Parentheses refers to standard deviations
Table 4.7.1 shows the individual retention of Ti nanoparticles that impregnated inside the
wood blocks which was calculated by using the retention formulae (AWPA, 2007) to
compare with the individual weight of Ti nanoparticles which was obtained by acid
digestion.
Obviously, there is a huge difference between the retention and weight of the impregnated
TiO2 nanoparticles into the wood blocks since they are obtained by different ways. The
retention showed in the table here has taken the uptake of water into account, while the
weights obtained by acid digestion consist of mainly the titanium nanoparticles present and
not take the water uptake into account. Therefore, theoretically, the weight obtained by the
acid digestion is more accurate if compared to the retention which was calculated by using
the formulae.
Individual retention of Ti
nanoparticles
Individual weight of Ti
nanoparticles
Wood Blocks Retention
(mg)
Mean
Weight (mg) Mean
Control Wood 0 0 0 0
Wood prior to
leaching 1
21.490
19.48 (2.56) 1.216 1.2231 (0.014)
Wood prior to
leaching 2
15.860
1.211
Wood prior to
leaching 3
21.080 1.242
Table 4.7.1: Individual retention and individual concentration of Ti nanoparticles for wood blocks before leaching
39
0
1
2
3
4
5
6
7
8
9
0
0.0005
0.001
0.0015
0.002
0.0025
0.003
0.0035
0.004
0.0045
0 6 24 48 96 144 192 240 288 336
[Nan
o-T
iO2/T
i] B
efore
lea
chin
g
[Nan
o-T
iO2/T
i] A
Fte
r le
ach
ing
Time (Hours)
[Nno-TiO2] After leaching
[Nnao-Ti ] After Leaching
[Nano-TiO2] Before leaching
[Nano-Ti]Before leaching
4.8 Leach Rate
*Refers to Table E (I), E (III)
*Parentheses refers to standard deviation
Concentration of TiO2 nanoparticles Wood prior
to leaching 1
Wood prior
to leaching 2
Wood prior
to leaching 3
Concentration of TiO2 nanoparticles
in unleached blocks (mg/L) 8.1145 8.0818 8.2886
Mean of concentration of TiO2
nanoparticles in unleached blocks
(mg/L), Σ
8.1616(0.0908)
Concentration of Ti nanoparticles Wood prior
to leaching 1
Wood prior
to leaching 2
Wood prior
to leaching 3
Concentration of Titanium in
unleached blocks (mg/L) 4.8638 4.8442 4.9682
Mean of concentration of Titanium
in unleached blocks (mg/L), Σ 4.8921(0.0544)
Table 4.8 (a): Concentration of TiO2 nanoparticles impregnated in wood blocks before leaching
Table 4.8 (b): Concentration of Titanium nanoparticles impregnated in wood blocks before leaching
Figure 4.8: Mean Concentration of TiO2 Nanoparticles in Leachate versus Time
*(Refers to Table B in Appendices)
40
Table 4.8 (a) and (b) reveal the concentration of TiO2 or titanium nanoparticles
impregnated in wood blocks before leaching while Figure 4.8 shows the mean
concentration of TiO2 or titanium nanoparticles leached out from the replicate wood blocks
over two weeks. The initial concentration of TiO2 and titanium nanoparticles impregnated
within the wood blocks before leaching was 32.647±0.364 mg/L and 19.5683±0.2177
respectively. The leaching rate was observed to be high for the first 6 hours, then drop less
rapidly from 6 hours to 96 hours and no leaching of TiO2 or Ti nanoparticles occurred at
the end as shown in Figure 4.8. After 48 hours, no leaching was observed for all the treated
wood blocks.
The same trend of graph was also reported by Younes and Marzbani (2014). High leaching
rate in the beginning of experiment could be attributed to unstable titanium dioxide or
titanium nanoparticles on wood surface and also the high surface area exposed to water due
to the size of the wood blocks as reported by Temiz et al. (2014). Although the overall
amount of leached TiO2 or titanium nanoparticles was relatively small, an initial unfixed or
poorly fixed TiO2 nanoparticles moved out of the wood, followed by a rapid decline to a
more stable leaching rate.
From Figure 4.8, the standard deviation in error bar showed there were differences
between the leaching rates of different wood blocks replicates. This was due to the
different wood blocks consist of different chemical composition of structural
polysaccharides, such as cellulose, hemicellulose and lignin which would affect the
leaching rate.
Moreover, the treated wood using non-toxic metal alkoxides of titanium, aluminum, and
silicon which synthesis by sol-gel process could protect the wood against water and
prevent leaching of antimicrobial reagents even in lower concentration as reported by
*(Refer to Table E (I), E (III) in Appendices)
41
Tshabalala and Williams (2008). Therefore, low leaching rate of TiO2 or titanium
nanoparticles from the wood blocks was obtained as shown in Figure 4.8.
4.9 Analysis Results
*(Refer to Table B, Table E (I) and Table E (II))
Table 4.9(a) and (b) show the percentage of total titanium dioxide or titanium nanoparticles
leached out from the wood blocks. The low percentage of titanium dioxide or titanium
nanoparticles could be explained by the small particles size with a large surface area that
caused the nanoparticles remain stable within the wood blocks during leaching.
The low leaching percentage of titanium dioxide or titanium nanoparticles can also be
explained by the formation of stable complex (Hingston et al., 2001). For examples,
titanium elements present in the wood blocks would react with the existing OH to form Ti
Wood block Control
Wood
Leached
Wood 1
Leached
Wood 2
Leached
Wood 3
Weight of titanium dioxide nanoparticles
in leached blocks (mg)
0 2.0211 1.6080 2.2616
Total weight of titanium dioxide
nanoparticles in leached blocks (mg), Σ
0 5.8907
Weight of titanium dioxide nanoparticles
in each leachate (mg)
0 1.67×10-4
1.67×10-4
1.67×10-3
Total weight of titanium dioxide
nanoparticles in leachate (mg) , Σ
0 2.00×10-3
Percent nano-TiO2 leached (%) 0 0.0340%
Wood block Control
Wood
Leached
Wood 1
Leached
Wood 2
Leached
Wood 3
Weight of Titanium in leached blocks
(mg)
0 1.2115 0.9639 1.3556
Total weight of Titanium in leached
blocks (mg), Σ
0 3.5310
Weight of Titanium in each leachate
(mg)
0 1× 10-4
1× 10-4
1× 10-3
Total weight of Titanium in leachate
(mg) , Σ
0 1.2× 10-3
Percent Titanium Leached (%) 0 0.0340%
Table 4.9 (a): Total Percentage of TiO2 Nanoparticles leached out
Table 4.9 (b): Total Percentage of Titanium nanoparticles leached out
42
(OH) 6 complexes. Therefore, the complex formation would result in a low loss of titanium
dioxide or titanium nanoparticles.
Besides, the resulting charge properties and Van der Waals forces caused by nanometal
preparations were one of the factors since these properties and forces would cause low
leaching rate (Clausen et al. 2010). The low retention level of the wood blocks shown in
Table 4.7 was also one of the factors causing low leaching rate, with percentage leaching
decreasing with low retention level (Hingston et al., 2002).
The factor that caused low retention level was moisture content, which influences the
weight of TiO2 or Ti nanoparticles in the wood blocks. The moisture content would
interference the impregnation of TiO2 or Ti nanoparticles into the woods. More
nanoparticles could penetrate into the woods at the low moisture content (near 0%) due to
the presence of empty space. Swelling occurs in the cell wall with cumulative moisture
content, therefore, affecting the volume of the cell wall pores or empty spaces decreases,
which results in decreasing the nanoparticles impregnated into the woods (Hosseinzadeh
and Neyestani, 1988).
The internal wood spaces samples in the cell-wall were calculated with an average 0.9556 ±
0.0671% of moisture content (as shown in Table A in Appendices), which was low. At the
same time, titanium dioxide or titanium nanoparticles impregnated in the lumens and cell
walls would reduce the moisture content (Hubert et al., 2009).Therefore, more
nanoparticles could impregnate inside the wood. In addition, the dimensional stability of
the wood could be enhanced if the nanomaterial distribution was performed more uniformly.
However, there were various factors to influence leaching rate, such as preservative
formulation, leaching temperature, post-treatment handling, timber dimensions and
43
leaching media pH, salinity and temperature as well as complex formation and charge
properties (Lebow, 1996).
44
5.0 CONCLUSION AND RECOMMENDATIONS
Titanium dioxide nanoparticles prepared by the sol-gel process have non-uniform sizes and
not well-dispersed with small aggregates formation. The titanium dioxide nanoparticles
prepared were in anatase phase since most of them were spherical-like shape. However,
the dialyzed titanium dioxide nanoparticles were more dispersed, fewer impurities and
stable due to the elimination of unreacted reactant, acidic substances and reduction of ionic
strength through dialysis. Titanium dioxide nanoparticles which played an important role
as antifungal protect the wood from UV exposure and antidecay was successfully
impregnated into the woods by vacuum impregnation for leaching. The results showed that
few titanium dioxide nanoparticles leached out from the Dyera costulata (Jelutong) treated
wood blocks within 14 days. This could be caused by the titanium dioxide nanoparticles
which were able to prevent leaching through charge properties and Van der Waals forces
caused by nanometal preparations, large surface area, formation stable complexes and low
retention level.
However, there was no parameter for the leaching of wood blocks due to the limited of
time of this study. As such, parameters such as the concentration of nanoparticles, titanium
dioxide without nanoparticles, size of nanoparticles and species of wood block are
recommended for future study. Besides, the doping of titanium dioxide nanoparticles with
Boron or Silicon is suggested for future research and development to enhance the wood
protection application. Other than leaching test, decay test and termites’ resistance test
should be conducted.
P Ka
45
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7.0 APPENDICES Table A
* Parentheses refers to standard deviation
* Weight in grams of treating solutions absorbed by the block (g), G refers to Table D
Retention, kg/m3 =
Wood block Control
Wood
Leached
Wood 1
Leached
Wood 2
Leached
Wood 3
Unleached
Wood 1
Unleached
Wood 2
Unleached
Wood 3
Weight of wood block without glue (g) 1.8567 1.7862 1.9326 1.9027 1.7287 1.9176 1.6654
Weight of wood block after glue (g) 1.9294 1.8451 1.9767 1.9518 1.7928 1.9772 1.7452
Weight of glue (g) 0.0727 0.0589 0.0441 0.0491 0.0641 0.0596 0.0798
Oven-dry mass (g) 1.7423 1.6726 1.7871 1.7705 1.6345 1.7862 1.5632
Air-dry mass (g) , T1 1.7601 1.6884 1.8048 1.7861 1.6487 1.8054 1.5784
Moisture content (g) 0.0178 0.0158 0.0177 0.0156 0.0142 0.0192 0.0152
Moisture content (%) 1.0113 0.9358 0.9807 0.8734 0.8613 1.0635 0.9630
Mean of Moisture Content (%) 0.9556 (0.0671)
Weight of wood block after vacuum impregnation (g),
T2
4.2519 3.6762 3.2723 3.7359 3.6676 3.4167 2.9826
Weight in grams of treating solutions absorbed by the
block (g), T2-T1 (G)
2.4918 1.9878 1.4675 1.9498 2.0189 1.6113 1.4042
Grams of TiO2 nanoparticles in 100 grams of treating
Solution (g) (C)
0 0.9027 0.9027 0.9027 0.9027 0.9027 0.9027
Volume of the block (cm3) (V) 4.0000 4.0000 4.0000 4.0000 4.0000 4.0000 4.0000
Retention ( Uptake of chemicals ), kg/m3 0 4.4860 3.3118 4.4002 4.556 3.6363 3.1689
Mean of Retention , kg/m3 0 4.0660 (0.5340) 3.7871 (0.5762)
Total component gauge/assay retention, Σ 0 12.1980 11.3612
G=T2-T1, the weigh in grams of the treating solution absorbed by the
Block
C= Grams of preservatives in 100 grams of treating solution
V= Volume of the block in ml
52
Table B (a)
Volume of deionized water used: 100 mL
Table B (b)
* Parentheses refers to standard deviation
Time (hours)
Concentration of titanium dioxide nanoparticles in leachate (mg/L)
Treated Wood 1 Treated Wood 2 Treated Wood 3 Mean 6 1.67×10
-3 1.67×10
-3 8.34×10
-3 3.89×10-3
(3.14×10-3
)
24 0 0 6.67×10-3 2.22×10
-3 (3.14×10
-3)
48 0 0 1.67×10-3
5.57×10-4
(7.87×10-4
)
96 0 0 0 0
144 0 0 0 0
192 0 0 0 0
240 0 0 0 0
288 0 0 0 0
336 0 0 0 0
Time (hours)
Concentration of titanium nanoparticles in leachate (mg/L)
Treated Wood 1 Treated Wood 2 Treated Wood 3 Mean 6 0.001 0.001 0.008 3.33×10
-3 (3.33×10
-3)
24 0 0 0.005 1.67×10-3
(2.36×10-3
)
48 0 0 0.004 1.33×10-3
(1.89×10-3
)
96 0 0 0 0
144 0 0 0 0
192 0 0 0 0
240 0 0 0 0
288 0 0 0 0
336 0 0 0 0
Table B (a): Concentration of titanium dioxide nanoparticles in leachate over two weeks
Table B (b): Concentration of titanium nanoparticles in leachate over two weeks
53
Table C
Concentration of Titanium dioxide nanoparticles sample
Samples Concentration (mg/L)
X10 000 Replicate 1 0.983
X10 000 Replicate 2 1.107
X10 000 Replicate 3 1.152
Mean 1.081 (0.0715)
*Parentheses refers to standard deviation
M1 V1 = M2 V2
54
Table D *Parentheses refers to standard deviation
Time
( hours )
Leached Wood 1
Total Ti found in
solution ( mg/L)
Leached Wood 2
Total Ti found in
solution ( mg/L)
Leached Wood 3
Total Ti found in
solution ( mg/L)
6 hours
0.0002
0.0001
0.0001
0.0001
0.0001
0.0001
0.0005
0.0005
0.0005
Mean 0.00013(0.00005) 0.0001 (0) 0.0005(0)
24 hours
0
0
0
0
0
0
0.0004
0.0004
0.0004
Mean 0 0 0.0004(0)
48 hours
0
0
0
0
0
0
0.0001
0.0001
0.0001
Mean 0 0 0.0001(0)
96 hours 0
0
0
0
0
0
0
0
0
Mean 0 0 0
144 hours 0
0
0
0
0
0
0
0
0
Mean 0 0 0
192 hours 0
0
0
0
0
0
0
0
0
Mean 0 0 0
240 hours
0
0
0
0
0
0
0
0
0
Mean 0 0 0
288 hours
0
0
0
0
0
0
0
0
0
Mean 0 0 0
336 hours
0
0
0
0
0
0
0
0
0
Mean 0 0 0
55
Weight of sawdust used: 0.5 g Volume of dilution: 250 ml
Table E (I ) *Parentheses refers to standard deviation
Table E (II) *Parentheses refers to standard deviation
Samples Replicate Weight of Ti found in
solution (mg/L)
Mean
A. Blank 1 1
2
3
0.0063
0.0063
0.0063
0.0063 (0)
B. Blank 2 1
2
3
0.0363
0.0700
0.0295
0.0453 (0.0177)
C. Blank 3 1
2
3
0.0370
0.0353
0.0330
0.0351 (0.00164)
D. Blank 4 1
2
3
0.0098
0.0098
0.0098
0.0098 (0)
Samples Replicate Weight of Ti found in
blocks (mg/L)
Mean Minus
Blank
Leached Wood 1 1
2
3
2.2996
3.2375
1.8676
2.4682 (0.5718) B
Leached Wood 2 1
2
3
2.5105
1.1588
2.1328
1.9340(0.5694) A
Leached Wood 3 1
2
3
2.8580
2.9500
2.4320
2.7469 (0.2257) C
56
Table E (III) *Parentheses refers to standard deviation
Samples Replicate Weight of Ti found in
blocks (mg / L)
Mean Minus
Blank
Unleached Wood 1 1
2
3
1.60900
3.38400
2.40800
2.46700(0.7258)
C
Unleached Wood 2 1
2
3
1.83490
2.27330
3.18750
2.4319 (0.5635)
D
Unleached Wood 3 1
2
3
2.37330
1.43160
3.67680
2.4939 (0.9206)
D
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