Application of titanate nanotubes silicon dioxide (TNTSiO2) nanocomposite for the adsorption heavy metal (copper (II) ion) in aqueous solution

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY NGUYEN THUY TRANG APPLICATION OF TITANATE NANOTUBES-SILICON DIOXIDE TNT@SiO 2 NANOCOMPOSITE FOR THE ADSORPTION HEAVY META

THAI NGUYEN UNIVERSITY

UNIVERSITY OF AGRICULTURE AND FORESTRY

NGUYEN THUY TRANG

APPLICATION OF TITANATE NANOTUBES-SILICON DIOXIDE (TNT@SiO 2 ) NANOCOMPOSITE FOR THE ADSORPTION HEAVY METAL

(COPPER (II) ION) IN AQUEOUS SOLUTION

BACHELOR THESIS

Study Mode: Full-time

Major: Environmental Science and Management

Faculty: International Training and Development Center

Batch: 2012-2016

Thai Nguyen, 20/07/2016

Thai Nguyen University of Agriculture and Forestry

Degree Program Bachelor of Environmental Science and Management

Student name Nguyen Thuy Trang

Thesis Title Application of Titanate nanotubes-Silicon dioxide (TNT@SiO2)

nanocomposite for the adsorption heavy metal (Copper (II) ion)

nanocomposite and separated out of aqueous solution within 30 minutes reaction Results obtained in this study clearly show TNT@SiO2 nanocomposite is successful

for the adsorption heavy metals ion in solution

Keywords TNT@SiO2 nanocomposite , hydrothermal method,

adsorption, heavy metal, Cu(II) ion

Number of pages 56

Date of submission 30th August, 2016

Supervisor’s

signature

ACKNOWLEAGEMENT

Firstly, I would like to say thanks to the cooperation between Thai Nguyen University of Agriculture and Forestry and National Tsing Hua University for providing me an amazing opportunity to internship in Taiwan It brings me great pleasure to work and submit my thesis for graduation

I would like to express my deeply gratitude to Prof Dr Ruey- an Doong

whose guidance, encouragement, suggestion and very constructive criticism have contributed immensely to the evolution of my ideas during the project Without his guidance, I may not have this thesis

I sincerely thanks to Assoc Prof Dr Tran Thi Thu Ha for her advices,

assistance, sharing experiences before and after I went to Taiwan, helping me to understand and complete proposal and thesis

I am also thankful to Mr Nguyen Thanh Binh (PhD) and Ms Khuat Thi

Thanh Huyen for teaching me the synthesis of nanotubes and various other techniques and methods used in environmental field They were very helpful in providing me constructive feedback and suggestions on my project and helping me to successful complete several of my experiments and report Without them help and devotion, I would not be able to reach this stage

I am really fortunate to be in Prof Dr Ruey- an Doong’s lab Thanks to all the members in Professor Doong’s laboratory who hearty help me a lot when I work in

there

I also thank to my family for providing me emotional, unceasing encouragement and physical and financial support At last, I would like to thank all those other persons who helped me in completing this report Because of my lack knowledge, the mistake is inevitable, I am very grateful if I receive the comments and opinions from teachers and others to contribute my report

Sincerely,

Nguyen Thuy Trang

TABLE OF CONTENT

LIST OF FIGURES 1

LIST OF TABLES 2

LIST OF ABBREVIATIONS 3

PART I INTRODUCTION 4

1.1 Research rationale: 4

1.2 Research’s objectives 5

1.3 Research questions 6

1.4 Limitations 6

PART II LITERATURE REVIEW 7

2.1 Heavy metals 7

2.1.1.Definition and sources of heavy metals: 7

2.1.2.Characteristics of heavy metals: 7

2.1.3.Heavy metals pollution in the world and Vietnam 8

2.1.3.1 Heavy metals pollution in the soil 8

2.1.3.2 Heavy metals pollution in coastal, marine environment 9

2.1.4.Effecting of heavy metals to environment and human’s health 10

2.1.5.The characteristics and health effects of Copper 12

2.1.6.Method for treament heavy metals in aqueous solutions 13

2.2 Nanomaterials: 13

2.2.1.Titanate nanotubes ( TNT) : 15

2.2.1.1 Overview of Titanium dioxide: 15

2.2.1.1.1.Titanium oxidation structures and properties: 15

2.2.1.1.2.Titanate nanotubes(TNT) 16

2.2.2.Overview of SiO2: 17

2.2.3.Overview of nanocomposite 18

2.2.3.1 Definition and characteristics of nanocomposite 18

2.2.3.2 SiO2@TNT nanocomposite 19

PART III MATERIALS AND METHODS 20

3.1 Materials 20

3.2 Methods: 22

3.2.1.The synthesis of TNT: 22

3.2.2.The synthesis of TNT@SiO2 nanocomposite 23

3.2.3.Adsorption experiment: 23

3.2.4.The methods for determining the characteristics of materials 24

3.2.4.1 X-ray Diffraction ( XRD) 25

3.2.4.2 Scanning Electron Microscopy ( SEM) 26

3.2.4.3 Transmission Electron Microscopy ( TEM) 28

3.2.4.4 Fourier transform infrared spectroscopy ( FTIR) 29

3.2.4.5 Zeta potential (ZP) 30

3.2.4.6 Atomic absorption spectroscopy 32

PART IV RESULTS 33

4.1 The X-ray diffraction of TNT, SiO2 and SiO2@TNT composite 33

4.2 Morphology of TNT, SiO2 and TNT@SiO2 composite 34

4.3 Fourier transform infrared (FTIR) spectrum of SiO2, the synthesis TNT and TNT@SiO2 37

4.4 Zeta potential 38

4.5 Application of TNT@SiO2 for the adsorption Cu(II) ion 39

PART V DISCUSSION AND CONCLUSION 41

5.1 Discussion 41

5.2 Conclusion 42

REFERENCES 43

LIST OF FIGURES

Figure 2.2.1.1.1: Crystal structure of the three forms of titanium dioxide 15

Figure 2.2.2 : Crystal structure of SiO2 17

Figure 3.1.2: Some instruments used for this study 21

Figure 3.2.1: Schematic of the synthesis TNT 22

Figure 3.2.2: Schematic of the synthesis TNT@SiO2 23

Figure 3.2.3 : The samples of Cu(II) ion (10mg/L) and TNT@SiO2 of the adsorption experiment at pH=5 in the different times 24

Figure 3.2.4.1: Schematics of X-ray diffractometer technique used for crystal structure analysis 26

Figure 3.2.4.2: Schematic diagram of SEM 28

Figure 3.2.4.3: Schematic diagram of TEM 29

Figure 3.2.4.5: The effect of pH on Zeta potential 31

Figure 3.2.4.6: Schematic of an atomic-absorption experiment 32

Figure 4.1: XRD patterns of TNT, SiO2 and SiO2@TNT composite 33

Figure 4.2 A: SEM images of the synthesis TNT(a) and TNT@SiO2 composite (b) 34

Figure 4.2 B: TEM images of SiO2, the synthesis TNT and TNT@SiO2 composite 36

Figure 4.3: FTIR spectrum of SiO2, the synthesis TNT and TNT@SiO2 37

Figure 4.4: The effect of pH to zeta potential of SiO2@TNT 38

Figure 4.5: The adsorption Cu (II) ion (10mg/L) by TNT@ SiO2 at pH=5 in aqueous solution at room temperature 39

LIST OF TABLES

Table 3.1.1: Sources of chemical materials 20

LIST OF ABBREVIATIONS

SiO2@TNT or

TNT@SiO2

SiO2 + TiO2 nano composite

TiO2 + SiO2 nano composite

FTIR Fourier transform infrared spectroscopy

PART I INTRODUCTION

1.1 Research rationale:

Economic and social development have produced many benefits – raising standards

of living and improving quality of life across the world – it has also resulted in the depletion of natural resources, the degradation of ecosystems and environmental issues Environmental pollution is a controversial issue not only in Vietnam but also in the world

With about 70% of the earth’s cover being water, it undeniably becomes one of our greatest resources Furthermore, roughly 70% of an adult’s body made up of water So, water is very important for human Water pollution is an appalling issue, powerful enough to lead the world on a path of destruction Water is an easy solvent, enabling most pollutants to dissolve in it easily and contaminate it The most basic effect of water pollution is directly suffered by the organisms and vegetation that survive in water, including amphibians On a human level, several people die each day due to consumption of polluted water contained heavy metals Heavy metals are particularly problematic because, unlike most organic contaminants, they are non-biodegradable and can accumulate in living tissues, posing great threat to both human health and ecological environment The most common heavy metals mainly include mercury, cadmium, lead, chromium, arsenic, zinc, copper, nickel, cobalt, etc To date, various methods have been proposed for efficient heavy metal removal from waters, including but not limited to coagulation, chemical precipitation, membrane filtration, reverse osmosis, solvent extraction, flotation, ion exchange and adsorption But, adsorption is one of the highly selective methods for removing heavy metals from aqueous solutions This is an economical technique which also offers numerous advantages

resulting from the vast number of available adsorbents With the development of modern technologies, a very wide range of materials have come to be used as hazardous metal adsorbents, from natural substances to highly selective synthetic systems

Titanium oxide nanotube (TiO2 nanotube/ TNT) is one of the nanostructured oxides with tubular structure TiO2 is well known as a wide gap semiconductor oxide, high photocatalytic activity, inexpensive, chemically stable, harmless, large specific surface area and high pore volume, has no absorption in the visible light region, and a potential material for the adsorption of metal ions in aqueous solution

SiO2 was contained in waste panel glass of television, notebook, smartphone etc,

To contribute for protecting the environment, with efforts are being done in recent year

to coat TiO2 on high surface area supports such as silica (SiO2) and alumina (Al2O3) to improve surface area of TiO2(Hanprasopwattana A et al.,1997; Yuranova T et

al.,2006) Recent studies showed that TiO2-SiO2 mixed oxides might be good

combination to become one of the best catalyst for oxidation reactions ( Yoshida H et

al., 2000) Thus, SiO2@TNT nano composite with high specific surface area of TNT is promising in treating contaminated aqueous solution

Considering all aspects and issues mentioned above, I propose research:

“Application of Titanate nanotubes-Silicon dioxide (TNT@SiO2) nanocomposite for the adsorption heavy metal ( Copper (II) ion) in aqueous solution.”

1.2 Research’s objectives

The objective of this study was to fabricate, investigate and develop of TNT@SiO2 nano composite for the adsorption of Cu (II) ion from aqueous solution

To further approach and understand about the synthesis process, nanostructures, formation mechanism, various physicochemical characteristics, and evaluate the properties and application for the adsorption of TNT@SiO2 nano composite through a hydrothermal method

Estimation of the adsorption capacity of some heavy metal ions in aqueous solutions

The characteristics of nano composite materials were determined by XRD, TEM, SEM, FTIR, and AAS

The fabrication of new materials TNT@ SiO2 nano composite will make a significant contribution in waste water treatment and improve the domestic water efficiency as well as contribute to the environmental protection

1.3 Research questions

What is the characteristics of TNT@SiO2 nano composite?

How about the adsorption capacity Cu (II) ion of TNT@SiO2 nano composite

in aqueous solution?

1.4 Limitations

Because the time for an internship was too short, this research project cannot perform any other experiments

PART II LITERATURE REVIEW

2.1 Heavy metals

2.1.1 Definition and sources of heavy metals:

There is not clearly about definition of a heavy metal But the high densities of native metals such as copper, iron and gold may have been noticed in prehistory (Raymond 1984, p 9) Heavy metals are found naturally in the earth, and become concentrated as a result of human caused activities Common sources are from mining and industrial wastes; vehicle emissions; lead-acid batteries; fertilisers; paints; treated woods; aging water supply infrastructure ( Harvey, Handley & Taylor 2015); and

microplastics floating in the world's oceans ( Howell et al., 2012; Cole et al., 2011,

pp 2589‒2590)

Heavy metals have a high atomic weight and a density at least 5 times greater than that of water Heavy metals can be classified into three different types including toxic metals (such as Hg, Cr, Pb, Zn, Cu, Ni, Cd, As, Co, Sn, etc.), precious metals (such as

Pd, Pt, Ag, Au, Ru etc.) and radionuclides (such as U, Th, Ra, Am) ( Bishop.,2012) And toxic metals are the most impact to human’s health and life

2.1.2 Characteristics of heavy metals:

Heavy metals are a natural constituent on earth commonly known with properties such as having persistence, high toxicity and also serving as non-biodegradable pollutants when they accumulate in the ecosystem Heavy metals can create adverse effects on environmental and human health due to their toxicity Some heavy metals are found in the body and essential for human health, such as iron, zinc, magnesium,

cobalt, manganese, molybdenum and copper, although the amount is very small but it

is present in metabolism However, at excess level of the essential elements can endanger the life of the organism (Foulkes, 2000) The remaining metal elements are unnecessary elements and can be highly toxic when present in the body; however, the toxic is only present when they enter the food chain These elements include mercury, nickel, lead, arsenic, cadmium, aluminum, platinum and copper in the form of metal ions Heavy metals enter plant, animal and human tissues via air inhalation, diet and manual handling Thus, heavy metals can bind to vital cellular components, such as structural proteins, enzymes, and nucleic acids, and interfere with their functioning Symptoms and effects can vary according to the metal or metal compound, and the dose involved Broadly, long-term exposure to toxic heavy metals can have carcinogenic, central and peripheral nervous system and circulatory effects

2.1.3 Heavy metals pollution in the world and Vietnam

Nowadays, pollution becomes increasingly prevalent in our daily life In some areas, it has a fairly negative impact on our health Among all the pollutions, heavy metal is an important part which should never be neglected

2.1.3.1 Heavy metals pollution in the soil

Heavy metals contamination of soils currently has become one of the most serious environmental problems Some of the heavy metals are micronutrients necessary for plant growth, such as Zn, Cu, Mn, Ni and Co, while others have no known function, such as Cd, Pb and As In a national survey commissioned by the United Kingdom, the Department of the Environment analysed samples collected from

November 1981 to June 1982 from 53 locations in England, Scotland, and Wales

(Thornton et al., 1990) The results showed that 93 % of the garden soils exceeded

2,000 mg·kg-1 Pb In Derbyshire, the Pb concentration was within the range of 1,180 – 22,100 mg·kg-1 , while the Pb concentration in the vegetable plot soil the range was 1,140 – 26,500 mg·kg-1 Several studies reported that the Cd content in soils near the smelter or metallurgical factories were very high For example, in Poland, at a site located 600 m away from a metallurgical factory, the Cd content in soil was 250 mg·kg-1 (Greszta and Godzik, 1969) In Vietnam, by using wastewater for the irrigation of crops, the land might have been exposed to heavy metals contamination

(Nguyen et al., 2001) According to Le and Nguyen (1998) and to Ho and Nguyen

(2003), most of the soil pollutions with Pb and Cu are caused by the traditional craft villages and heavy metal recycling activities

2.1.3.2 Heavy metals pollution in coastal, marine environment

Heavy metals contamination in coastal and marine environments is becoming

an increasingly serious threat to both the naturally stressed marine ecosystems and humans that rely on marine resources for food, industry and recreation Heavy metals are introduced to coastal and marine environments through a variety of sources and activities including sewage and industrial effluents, brine discharges, coastal modifications and oil pollution There is an increasing trend of heavy metal pollution

in sediments of several coastal waters in the western part of Indonesia Heavy metals such as Pb, Cd, Cu, Cr and Zn in sediments were recorded relatively high in concentration Variation for each metal were in the following: 0.42 -101.28 mg Pb kg-1

dry weight (dw), 0.03 -9.86 mg Cd kg-1 , 0.10 -61.34 mg Cu kg -1 , 0.99 -42.10 mg Cr

kg -1 and 0.46 -122.00 mg Zn kg -1 (Zainal Arifin., 2001) While in the water of the Yangtze River Basin, China, the concentrations of Cd, Cu, Pb and Zn are 0.080, 7.91, 15.7 and 18.7 microg/l, respectively This metals come from human activities, industrial emission, wastewater and solid waste These contaminants pollute drinking water and food, and threaten human health Some diseases resulting from pollution of geological and environmental origin, were observed with long-term and non-reversible effects (Cheng S., 2003) In Vietnam, in four surveyed stations from Quang Ninh province to Thai Binh province, the concentration of some metals, such as copper, exceeded the permissible concentrations (0.01 mg/litre), reaching concentrations of 0.017–0.048 mg/litre of dissolved copper Mercury contamination may prove very harmful to aquatic organisms, one third of the samples exceeded permissible concentrations In the water layer near the bottom of Bach Dang and Thai Binh river mouths it was 0.005 mg/litre and in other stations it is now 0.0002 mg/litre In some areas, Fe2+ exceeded the permissible concentration (0.50 mg/litre), reaching Fe2+

concentrations of 1.20–1.65 mg/litre (FAO/NACA., 1995)

2.1.4 Effecting of heavy metals to environment and human’s health

Environmental pollution due to toxicity of heavy metals cause ecological imbalance, decrease crop yield , degrade many populations organisms, and effect to human's health have been found in many countries around the world In the mining areas located in the districts of Jajpur, Keonjhar, Mayurbhanj and Sundargarh districts

of Odisha in India, nearly 45% to 67% of iron and 45% to 54% of chromium contamination are reported This high concentration of salts and metals acts as stress to plants affecting the yield of crops and viability of flora and fauna adversely not only in

the area of location but all adjoining areas by spreading thus raising concern The major effects of heavy metals on seeds are manifested by overall abnormalities and decrease in germination, reduced root and shoot elongation, dry weight, total soluble protein level, oxidative damage, membrane alteration, altered sugar and protein metabolisms, nutrient loss all contributing to seed toxicity and productivity loss (Sunil Kumar Sethy & Shyamasree Ghosh., 2013) Besides, fish are relatively situated at the top of the aquatic food chain The concentrations of heavy metals (Cu, Zn, Pb, Cd, Fe and Mn) were measured in the liver, gills and muscles of fourteen benthic and pelagic fish species collected from three main landing areas (Shalateen, Hurghada and Suez)

in the Egyptian Red Sea The levels of heavy metals varied significantly among fish species and organs Thus, the content of toxic heavy metals in fish affected to fish populations, especially, to human’s health as renal failure, liver damage,

cardiovascular diseases and even death (Kh M El-Moselhy et al., 2014)

The main threats to human health from heavy metals are associated with exposure to lead, mercury, cadmium, arsenic, copper, zinc, and chromium Exposure

to arsenic is mainly via intake of food and drinking water, food being the most important source in most populations Long-term exposure to arsenic in drinking-water

is mainly related to increased risks of skin cancer, but also some other cancers, as well

as other skin lesions such as hyperkeratosis and pigmentation changes Occupational exposure to arsenic, primarily by inhalation, is causally associated with lung cancer Clear exposure-response relationships and high risks have been observed Cadmium affected to kidney damage but possibly also bone effects and fractures Mercury can cause mutations and genetic damage, while copper, lead can cause brain and bone

damage In Thai Nguyen province of Vietnam, people living around Pb-Zn mining areas occurred some sign of heavy metal poisoning even cancer disease.And in a lead recycling village in Hung Yen province of Vietnam, a lot of children became less intelligent than the children in other places of this province (Ha, C T., 2011).

2.1.5 The characteristics and health effects of Copper

Characteristics of Copper

Copper was one of the earliest elements known to man At one time, it could be found lying on the ground in its native state or uncombined state Copper's distinctive red color made it easy to identify However, the commonly encountered compounds are copper (II) salts, which often impart blue or green colors Copper is obtained from minerals such as azurite, or basic copper carbonate (Cu2(OH)2CO3 ); chalcocite, or copper glance or copper sulfide (Cu2S); chalcopyrite, or copper pyrites or copper iron sulfide (CuFeS2 ); cuprite, or copper oxide (Cu2O); and malachite, or basic copper carbonate (Cu2(OH)2CO3 ) And copper forms a rich variety of compounds, usually

with oxidation states +1 and +2, which are often called cuprous and cupric, respectively (Holleman, A F et al., 2001)

Health effects

Copper is an essential micronutrient for both plants and animals A micronutrient is an element needed in minute amounts to maintain good health in an organism A healthy human has no more than about 2 milligrams of copper for every kilogram of body weight However, a large amounts of copper in the human body are usually a problem One exception is the condition known as Wilson's disease

Some people are born without the ability to eliminate copper from their bodies The amount of copper they retain increases The copper level can become so great it begins

to affect a person's brain, liver, or kidneys Mental illness and death can result (Chemistry Explained, 2016)

2.1.6 Method for treament heavy metals in aqueous solutions

Environmental pollution by heavy metal is arising as the most endangering tasks to both water sources and atmosphere quality today Revelation to heavy metals, even at trace levels, is harmful to human beings Thus, removal of undesirable metals from water sources is considered as an important task that is still threatening to human's health and the environment There are some effective methods for the removal of heavy metal ions from water sources such as: chemical precipitation, membrane filtration, reverse osmosis, solvent extraction, flotation, ion exchange and adsorption Among these methods, adsorption offers flexibility in design and operation and, in many cases it generates high-quality treated effluents In addition, owing to the reversible nature of most adsorption processes, adsorbents could be regenerated by

suitable desorption processes for multiple use (B.J Pan et al., 2009) In addition, many

desorption processes are of low maintenance cost, high efficiency, and ease of

operation (S.P Mishra, et al., 1996) Therefore, the adsorption process is considered as

one of the major suitable technique for heavy metals removal from water/wastewater sources

2.2 Nanomaterials:

The rapid growth in nanotechnology has spurred significant interest in the environmental applications of nanomaterials Nanomaterials are excellent adsorbents

and catalysts (Khin et al., 2012) Since nanomaterials offer significant improvement

with extremely high specific surface area, numerous associated sorption sites, low temperature modification, short intraparticle diffusion distance, tunable pore size and

surface chemistry compared to other materials (Ju-Nam and Lead, 2008; Qu et al., 2013; Chen et al., 2007), extensive research have been carried out to remove heavy

metals from wastewater by developing and using various nanomaterials

Although traditional sorbents could remove heavy metal ions from waste water the low sorption capacities and efficiencies limit their application deeply To solve these defects of traditional sorbents nanomaterials are used as the novel ones to remove heavy metal ions in waste water Compared with traditional materials nano-structure adsorbents have exhibited much higher efficiency and faster rates in water treatment Nanomaterials used as sorbents for removing heavy metal ions in waste water should satisfy the following criterions; (a) the nano sorbents themselves should

be non toxic; (b) the sorbent should have relatively high sorption capacities and selectivity to the low concentration of pollutants; (c) the adsorbed pollutant should be removed from the surface of the nano adsorbent easily; (d) the sorbents should be infinitely recycled So far, a variety of nanomaterials such as carbon nanotubes, carbon based material composites, graphene, nano metal or metal oxides, and polymeric sorbents have been studied in the removal of heavy metal ions from aqueous solution, and the results indicate that these nanomaterials show high adsorption capacity

2.2.1.Titanate nanotubes ( TNT) :

2.2.1.1 Overview of Titanium dioxide:

2.2.1.1.1 Titanium oxidation structures and properties:

Titanium dioxide, also known as titanium (IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2 When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891, or CI 77891

TiO2 is polymorphous and it exits in three types of crystal structure: rutile, anatase and brookite The most common are anatase and rutile, since brookite is rather

unstable Anatase can be transformed into rutile at high temperatures(Floriano et al.,

2014) Brookite with its orthorhombic crystal system can be transformed into rutile

with the application of heat (Kadam et al., 2015)

In all three forms, titanium (Ti4+) atoms are coordinated to six oxygen (O2−) atoms, forming TiO6 octahedral(Pelaez et al., 2012)

Figure 2.2.1.1.1 was shown the crystal structure of the three forms of titanium dioxide (Shanon.,2012)

Figure 2.2.1.1.1: Crystal structure of the three forms of titanium dioxide (Source:

Shanon.,2012) ( Ti: Grey; O: Red)

Titanium dioxide is an n-type semiconductor that has a band gap of 3.2 eV for anatase, 3.0 eV for rutile, and ~3.2 eV for brookite(Goswami Pallabi., 2012) Titanium dioxide (TiO2) is the most widely investigated photocatalyst due to its strong oxidative properties, low cost, non-toxicity, chemical and thermal stability

2.2.1.1.2 Titanate nanotubes(TNT)

Inspired by the discovery of carbon nanotubes, one dimensional nanostructured materials have become a research topic owing to their unusual properties and potential applications Among the various semiconductors, titanate nanotubes (TNTs) have been subject of interest because of their cheap fabrication, unique one-dimensional

nanostructure, high surface area and electrical conductivity (D.V Bavykin et al., 2009; H.-H Ou et al., 2007) Titanium dioxide has been intensively investigated as a

potential sorbent due to its high chemical stability in the pH range 2- 14 and because the process is simple with a fast rate of adsorption and desorption

Titanate nanotubes (TNT) were prepared by hydrothermal method These defined and uniformly tubular materials are characterized by high specific surface

well-areas and pore volumes, and they possess good ion-exchange properties (Q Chen et

al., 2007) Particularly, TNT have many functional hydroxyl groups All the protons of these hydroxyl groups may be readily exchanged with heavy metal ions in aqueous

solutions (D.V Bavykin et al., 2006) Moreover, the hydrothermal method is very simple with high yield and reusable alkali solutions (Q Chen et al., 2002) Therefore, TNT may have great potential to adsorb heavy metals Doong et al., (2012) fabricated

titanate nanotubes (TNT) using an alkaline hydrothermal method and then calcined at

various temperatures ranging from 200 to 600oC in air for 4h for removal of bisphenol

A and Cu(II) ion The calcined TNT has good Cu (II) adsorption capacity

Figure 2.2.2 : Crystal structure of SiO2

(Source: Kyawthetlatt., 2013)

Silica is used primarily in the production of glass, optical fibers for telecommunications, whiteware ceramics (earthenware, stoneware, and porcelain) Silica is used as a desiccant It is the soul material for the semiconductor industry as it has good thermal and dielectric property Silicon dioxide also used as the supporting material of titanium dioxide to enhance the surface areas and the photocatalytic activity for the adsorption heavy metals

2.2.3 Overview of nanocomposite

2.2.3.1 Definition and characteristics of nanocomposite

A conbination of two or more materials with different physical and chemical properties and distinguishable interface defined, that is a composite With many advantages of composites over many metal compounds, such as high toughness, high specific stiffness, high specific strength, gas barrier characteristics, flame retardancy, corrosion resistance, low density, and thermal insulation.made nanomaterials, in particular nanocomposites, have diversified applications in different areas such as biological sciences, drug delivery systems, and wastewater treatment In nanocomposites, the nanoparticles were incorporated within different functionalized materials such as multiwalled carbon nanotubes, activated carbon, reduced graphene oxide, and different polymeric matrices

In recent years, water pollution is a huge issue and caused by the pollutants that result in severe environmental problems In recent years, various methods for heavy metal detection from water have been extensively studied One of the most effective methods is using nanocomposite These nanocomposites provide high surface area and

a specific affinity for heavy metal adsorption from aqueous systems The adsorption of different pollutants such as heavy metal ions and dyes from the contaminated water using nanocomposites has attracted significant attraction due to their characteristic properties such as extremely small size, very large surface area, absence of internal diffusion resistance, and high surface-area-to-volume ratio Metal oxide nanoparticles, including aluminum oxides, titanium oxides, magnesium oxides, cerium oxides, and ferric oxides, have been proved to be very efficient for the removal of various pollutants from the aqueous water Nanocomposites have better adsorption capacity, selectivity, and stability than nanoparticles Magnetic nanocomposites are also a very efficient class of nanocomposites in which magnetic nanoparticles have been used as the reinforcing material They have the advantages of both magnetic separation techniques and nano-sized materials, which can be easily recovered or manipulated with an external magnetic field They are also very effective for the removal of both organic and inorganic pollutants from the pollutant water( Ajay Kumar Mishra.,2015)

2.2.3.2 SiO 2 @TNT nanocomposite

An increased interest in inorganic oxide systems has prompted the dynamic development of methods for their synthesis and functionalisation This interest stems from their specific physicochemical properties such as specific surface area or stability, which are vital for the production of composite systems

In order to contribute for protecting the environment, mesoporous composites from waste panel glass of Television, Notebook, Smartphone is expecting for a good absorbent component to do this experiment with the composition are SiO2 (60%),

Al2O3 (18%), B2O3 (8.5%), CaO (3.0%) , MgO (3.0%) and SrO (7.5%)

PART III MATERIALS AND METHODS

3.1 Materials

The nanomaterials were synthesized by chemical materials and used some instruments

in National Tsing Hua University, Taiwan

3.1.1 Chemical materials

Almost the chemicals were used as received without further treament

Table 3.1.1: Sources of chemical materials

4 Copper (II) Nitrare