K.A.J.W Siriwardhana.

Promising SriLankan minerals for Nano-technology.

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Nanotechnology is manipulation of matter on an atomic, molecular, and supra-

molecular scale. In reality, nanotechnology is an enabling technology providing tools for the

fabrication, manipulation and control of materials at the atomic level. At the Heart of

nanotechnology, it brings into collaboration ideas in chemistry, physics and biology mixed and

blended with engineering and medicine. Scientists and engineers have shown an active

interest in nanotechnologies because at sizes below 100 nm, the fundamental chemical or

electrical properties of materials can change.

Applications of nanotechnology are enabled by Nano-materials, which have novel optical,

electric or magnetic properties. The building blocks of nanotechnology are semiconductors,

metals, metal oxides, carbon materials and organics. The emerging commercial growth areas

in nanotechnology are Nano-materials and Nano-materials processing, Nano-biotechnology,

Nano-photonics, Nano-electronics and Nano-instrumentation.

Sri Lanka is stepping towards development taking hand in hand with Nano technology, by compromising effort to uplift the scientific studies through on going researches. Natural resource availability of Sri Lanka is a plus mark for the development. We may not be able to compete with world’s giants. But definitely there are many paths which we can take. One is water purification methods. We can focus on creating nanofilters to produce clean drinking water without heating the water to boiling level which consumes lot of energy. Almost all the microbes are in micrometer range which is smaller than nano meter scale. Hence this is very much reliable and efficient than boiling water. Scientists in the world have found certain materials, such as Titanium (Ti), when used under this nanotechnology will show characteristics destroying organic material on clothes. Dirt is an organic material. When kept under the sun it destroys this dirt, hence water and soap is not needed. For industries and services, where mass scale washing take place this can bring marvelous changes. We have a potential in this new concept. Most prominent minerals which are leading in nanotechnology world in Sri Lanka are graphite, quartz, mineral sand and clay.

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Graphite-

Carbon is a major element that is available all over the universe. It makes up approximately 20% of the human body. It is a key ingredient in the fossil fuels. Aside from the naturally occurring forms of carbon, graphite and diamond, carbon is also found in the nanostructured forms of fullerenes (or buckyballs) and carbon nanotubes (CNTs).Carbon can form the hardest natural material known on earth, diamond, and it can also form one of the softest materials, graphite. The properties of each material change as the arrangement of atoms changes. When carbon atoms form tiny tubes, called carbon nanotubes, the tubes are twice as strong as steel but weigh six times less. In diamond, each carbon atom is bonded to four other carbon atoms. This creates a three dimensional network of bonds. The extended network of bonding is where diamond gets its strength. In graphite, the carbon atoms are only bonded in two dimensions. The carbon atoms form layered sheets of hexagons. Since there are no bonds between the layers, the layers can easily slip off one another.

Fullerenes (Buckyballs)-

In 1996 Richard Smalley, Robert Curl, and Harold Kroto were awarded the Nobel Prize in chemistry for discovering a new form of carbon - the buckminster fullerene, or buckyball. A buckyball looks like a nanometer-sized soccer ball made from 60 carbon atoms.

Fig 1: Bucky ball.

Carbon Nanotubes-

The structure of a carbon nanotube is like a sheet of graphite rolled up into a tube. Depending on the direction of hexagons, nanotubes can be classified as either zigzag, armchair or chiral. Different types of nanotubes have different properties. When scientists make nanotubes, they tend to get a mixture of several types. A major challenge in nanoscience today is finding a way to make just one type of nanotube. Different types of carbon nanotubes can be produced in various ways. The most common techniques used nowadays are; arc discharge, laser ablation, chemical vapor deposition and flame synthesis.

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Fig 2: (a) armchair, (b) zigzag, (c) chiral

Carbon nanotubes are produced using the Sri Lankan vein graphite. A metal catalyst free, low cost process of manufacturing carbon nanotubes (CNT) using

Sri Lankan graphite as anode and cathode, in the absence of external cooling, in an inert gas atmosphere is presented in this paper. The CNT yield has been analyzed using High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM) and Raman spectroscopy.

The latest research has discovered a new chemical process to combine carbon nanotubes with natural rubber compounds to enhance its flexibility and strength. What’s more, the process has been found to enhance the mechanical and electrical properties without sacrificing the elasticity of the material. Incidentally unknown to many of us global and local rubber industry has been using the concept of combining carbon black nanoparticles to reinforce the strength and flexibility of rubber. Mainly used in the production of automobile industry related rubber products including tires, tubes, suspension top cups, cab mounts and suspensions, the effect that the primary hybrid fillers like carbon black have on the properties of natural rubber including strength, viscosity, vulcanization rate, cross-link density, hardness, modulus, thermal

and electrical conductivity has been long known. Nano-enabled detection and sensing systems can significantly improve the sensitivity

of pollution sensors, by detecting even a few ions of a chemical or biochemical pollutant. Additionally miniaturization could enable highly accurate, sensitive, simple and affordable field testing of water sources for acidity and presence of biological and non-biological pollutants.

Capacitive deionization is a method presently used for water desalination. Carbon-based materials (activated carbon, CNT) are used as the electrode material in such electrochemical cells. With nano-composite based electrodes, capacitive deionization can be extended to cover a wider range of contaminant removal. This will be beneficial not only for Sri Lanka, but also for many other countries in the region having ionic impurity related water issues.

Having a diameter of about 1nm, only water molecules can penetrate through CNTs while all other common pollutants are confined outside the CNT walls. CNTs can in principle allow the removal of almost all the impurities in water including organic, inorganic and biological contaminants. Therefore this can be thought of as the smartest water purification technique to emerge.

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Applications-

AFM probe tips-Single- walled carbon nanotubes have been attached to the tip of an AFM probe to make the tip “sharper”. This allows much higher resolution imaging of the surface under investigation. Flexible probe prevents the damage happening to the sample surface.

Flat panel display screens- When a nanotube is put into an electric field, it will emit electrons from the end of the nanotube like a small cannon. If those electrons are allowed to bombard a phosphor screen then an image can be created.

Nanocomposite materials- Dr. Morinobu Endo at Shinshu University mixed nylon with carbon fibers (100-200 nm diameter threads made in a similar manner to nanotubes), creating a nanocomposite material that could be injected into the world’s smallest gear mold (as of 2004). The carbon fibers have excellent thermal conductivity properties that cause the nanocomposite material to cool more slowly and evenly allowing for better molding characteristics of the nanocomposite. The “improved” properties of the nanocomposite allow it more time to fill the tiny micron-sized mold than nylon would by itself.

Hydrogen storage- Carbon nanotubes are able to store hydrogen and could provide the safe, efficient, and cost-effective means to store hydrogen gas needed for the fuel cell. Hydrogen atoms bond to the carbon atoms of the nanotube, and can be later released with slight changes in temperature and pressure. While nanotube-based hydrogen fuel cells are promising, there are no viable products on the market yet.

Actuators/Artificial muscles- An actuator is a device that can induce motion. In the case of a carbon nanotube actuator, electrical energy is converted to mechanical energy, causing the nanotubes to move. Two small pieces of “buckypaper,” paper made from carbon nanotubes, are put on either side of a piece of double-sided tape and attached to either a positive or a negative electrode. When current is applied and electrons are pumped into one piece of buckypaper and the nanotubes on that side expand causing the tape to curl in one direction. This has been called an artificial muscle, and it can produce 50 to 100 times the force of a human muscle the same size. Applications include: robotics, prosthetics.

Chemical sensors- Semiconducting carbon nanotubes display a large change in conductance in the presence of certain gases. Researchers have been able to use nanotubes as sensors by exposing them to gas and measuring the change in conductance. Compared to conventional sensors, carbon nanotubes provide the advantages of a smaller size, an increased sensitivity, and a faster response.In March 2005, researchers at the Naval Research Laboratory were able to detect minute amounts of sarin gas in under 4 seconds using a prototype nanotube gas sensor. In the future, nanotube sensors could be used for security and environmental applications.

Nanoscale electronics- One of the most significant applications is nanotube transistors. Transistors are devices that can act like an on/off switch or an amplifier for current and are used in nearly every piece of electronic equipment in use today. Scientists have been able to use semiconducting nanotubes as compact, more efficient alternatives to conventional transistors.

Drug delivery with Buckyballs- Scientists are also testing fullerenes for drug delivery. Many drug molecules can be attached to a fullerene. The medicine loaded fullerene can then be attached to an antibody. Antibodies are Y-shaped proteins that can

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recognize and attach to things in the body called antigens. Viruses, bacteria and diseases in the body each have unique antigens. The antibody finds the disease in the body then the attached fullerene delivers the appropriate medicine.

Fig 3: Nano carbon structures.

Fig 4: electronics.

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Quartz-

Silica is the common name for materials composed of silicon dioxide (SiO2) and occurs in crystalline and amorphous forms. Crystalline silica exists in multiple forms. Quartz, and more specifically α-quartz is a widespread and well-known material. Upon heating, α-quartz is transformed into β-quartz, trydimite and cristobalite. Porosil is the family name for porous crystalline silica. Quartz exists in natural and synthetic forms, whereas all porosils are synthetic. Amorphous silica can be divided into natural specimens (e.g., diatomaceous earth, opal and silica glass) and human-made products. The application of synthetic amorphous silica, especially silica nanoparticles (SNPs), has received wide attention in a variety of industries. SNPs are produced on an industrial scale as additives to cosmetics, drugs, printer toners, varnishes, and food. In addition, nanosilica is being developed for a host of biomedical and biotechnological applications such as cancer therapy, DNA transfection, drug delivery, and enzyme immobilization.

Major part of silicaproduced throughout the world is from silica sand.High purity silica sand is not so common; yet, high purity quartz is readily available in many areas of Sri Lanka. Most of these areas havereasonably large vein quartz deposits, (originated as veins) having very high purity (99.5 percent of SiO2).Vein type quartz deposits occur, abundantly,in Pussella, Opanayake, Rattota, Naula, Galaha, Mahagama (Embilipitiya) and Wellawaya areas.

Nanoparticles are obtained by direct synthesis of silica sol or by crystallization of nano-sized crystals of quartz or porosils. The particle size is determined by the synthesis parameters. Amorphous silica sol particles tend to adopt the spherical shape so as to reach a minimum of interfacial surface area. The particle size of commercial silica sols prepared from sodium silicate is from 10 to 25 nm. Grinding and milling processes reduce particle size. These techniques are most often applied to quartz, silica gel and vitreous silica. The obtained products generally have a broad size distribution.

C Quartz can be applied to virtually any surface: glass, wheels, plastics, leather, and rubber.

Ultra hard coating- C Quartz contains ceramic nano particles, which create an

extremely hard finish that is scratch-resistant and durable. The average thickness of C quartz layer is between 0.7 µm - 1.5 µm.

Weather-resistance- CQuartz provides durable protection against rain, sun, salt, and anything else Mother Nature throws at it. The anti-corrosive coating holds up in all weather conditions.

High gloss shine. CQuartz contains nano fiber glass, resulting in a deep, reflective shine.

Water and oil proof finish. CQuartz provides incomparably strong water and oil repellency. This hydrophobic effect prevents water spots and oily stains from attaching to the paintwork.

Smooth, dirt repellent surface. CQuartz's nano particles fill in tiny swirls and imperfections in the paint to make it perfectly smooth. Therefore, dirt and dirty water cannot settle into any crevices. The finish is also resistant to bugs,

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UV rays, acids, and salts. Plus, the slick surface is anti-static and washes off easily.

Anti-Calcium Effect. CQuartz prevents mineral deposits from bonding to the vehicle's surface so water spots can be wiped off.

Detergent-resistant protection. CQuartz cannot be removed by water, alkaline or other detergents, or by pressure washers. It lasts up to two years!

Self-cleaning effect. Most dirt and debris will not stick in the first place so you may find yourself washing your vehicle much less often.

Table 1: Overview of silica materials and relevant properties

Material Nature of product

Particle size Porosity Applications

Colloidal

silica Solution 1-1000 nm Dense Binders, ink

Stober silica Solution 10-1000 nm Tunable porosity Research

Precipitated

silica Powder

5-6 nm primary particles

precipitated to 500 nm -

50 μm aggregates

Tunable porosity

Filler

and

performance

additive

Silica gel Powder

0.5 - 5 nm primary

particles gelled to

networks and milled to

500 μm - 6 mm

aggregates

Tunable, void

spaces between

primary particles

Dessicant,

filler

and

performance

additive

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Mineral sand-

The Pulmoddai deposit is about six kilometres in length with an average width of 100 meters and is estimated to contain six million tonnes of heavy sands with an average composition of 70-72 percent ilmenite, 8-10 percent zircon, 8 percent rutile and 0.3 percent monazite. This unique deposit is replenished during the northeast monsoon and the rate of such replenishment is not known.

SLINTEC has developed a process to produce titanium dioxide starting with the ilmenite extracted from Pulmoddai and the signing of this agreement has in turn initiated the commissioning of a pilot plant and in the future, a large-scale commercial plant. Through the venture, the entities will move into commercial production of titanium and in time, will set up a state-of-the-art processing plant to produce nano titanium.

Titanium dioxide (Ti02) is one of the heavily used oxides. Nearly 60% of the world titanium oxide production is consumed by the paint industry. In addition to paints and coatings, printing ink, paper, rubber, textile, polyester fibre, rayon, plastic, leather, detergent, electronic, pharmaceutical, cosmetic, refractory industries use TiO2 as a raw material. Both TiO2 and nano TiO2 demand is projected to grow as above industries are growing. Especially, in the case of TiO2 the world production is struggling to keep up with the increasing demand. This has been indicated in the recent price increase (in 2011 reaching nearly $4000 per MT) and opening of several new manufacturing plants by the major titanium dioxide manufacturers around the world.

Significant research into nanotechnology in the last decade has shown promising new applications for titanium dioxide. As an example, titanium dioxide nanoparticles are used in dye-sensitised solar cells (DSSC), a relatively new photovoltaic technology which mimics the way plants convert sunlight into energy, although in this case the sunlight is transformed into an electrical current. The potential applications are widespread and range from lightweight lowpower markets to large-scale applications. Other areas of research for the application of titanium dioxide nanoparticles include as an arsenic removal agent in water treatment facilities, cancer treatments (ability to target and destroy cancer cells), and cement that absorbs pollution.

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Clay-

Nanoclays, which consists of stacks of layers which occur in nanometer scale in thickness with

interlayer charge balancing ions are interesting due to their potential applications in catalysis,

environmental remediation, controlled delivery and in the synthesis of nanocomposites with

organic/inorganic materials. Polymer clay nanocomposites show potential benefits such as

increased mechanical strength, decreased gas permeability, superior flame-resistance, and

even enhanced transparency when dispersed nanoclay plates suppress polymer

crystallization. Depending on chemical composition and nanoparticle morphology, nanoclays

are organized into several classes such as montmorillonite, bentonite, kaolinite, hectorite,

and Halloysite.

A small addition of nanoclays can greatly enhance the rheological properties of the paint

system. These properties prevent pigment settling and sagging on vertical surfaces and gloss

is minimally affected due to the low levels of addition. Thermal stability of grease is greatly

enhanced by the addition of small amount of organo-clays. Nanoclays provide colour

retention as well as good coverage in cosmetics and inks. The organic binds to the ionic

surfaces of layered silicates or organically modified nanoclay can act as a hydrocarbon

adsorbent material which is ideal for water treatment applications including removing oil,

grease, polychlorinated biphenyls, radionuclides and heavy metals.

Monazite-bearing alluvium in southwestern Sri Lanka, specifically stream sediments of the

Bentota Ganga River, have been described as one of the world’s most thorium-rich sediments.

This river system drains a region whose bedrock is mainly charnockitic gneiss and

garnetiferous gneiss. The Bentota Ganga River moves monazite with other heavy minerals,

which are deposited in seasonal beach sand deposits extending from Beruwala south to

Kikawala beach, a distance of about 12 km along the coast. Monazite was once mined on a

small scale at Kaikawala beach. Analyses of these monazites by Rupasinghe and others

showed them to be highly enriched in the light REEs relative to the heavy REEs, with a negative

Eu anomaly when the analyses were normalized to chondrite values.

Fig 5: montmorillonite clay particle layered structure.

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o Montmorillonite clay nano particles have such kind of properties like; Modified nano

clay in to polypropylene create active dye sites, Can impart flame retardant property

to the composite, Have the UV blocking capability.

o Sri Lankan nano clay compared to Na-Montmorillonite has a good UV blocking

capability.

o Nano clay particles embedded nano fibers can be produced using electro spinning

technology.

o Electro spinning technology has low output and should be further developed to make

fiber composite at bulk level.

o SL nano clay with layered structure can be successfully use to produce curtains with

UV blocking property.

Fig 6: Structure of montmorillonite.

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Ilmenite-

Titanium dioxide is manufactured by processing naturally occurring titanium containing rutile

(TiO2) or ilmenite (FeTiO3) minerals. Sri Lanka has vast deposits of ilmenite which is the major

raw material in TiO2 production. However, Sri Lanka currently does not produce any type of

value added TiO2 pigments. With the growth of nanotechnology, nano-TiO2 is now produced

worldwide using different methods varying the particle size from 1 nm to 100 nm. Nano-TiO2

has the tightly controlled particle size that increases both the refractive index and light

scattering properties as a result of the uniform particle size distribution and additional surface

area. Nano-TiO2 is particularly interesting in UV resistant surface coatings where it can act as

a UV reflector. Because of the higher photo-catalytic activity nano-TiO2 can be used for anti-

fogging coatings where nano-TiO2 incorporated into outdoor building materials can

substantially reduce concentrations of airborne pollutants such as volatile organic

compounds and nitrogen oxides and as photo-catalyst coating which assist in deactivation of

bio-contaminants. In this investigation nano-TiO2 and pigmentary TiO2 were synthesized using

titanyl sulfate precursor, which can easily be produced by Sri Lankan ilmenite with sulfuric

acid according to the sulfate process. Synthesized nano-TiO2 was characterized by X-ray

diffraction (XRD), Raman spectroscopy, scanning transmission electron microscopy (STEM)

and scanning electron microscopy (SEM) methods. The photocatalytic activity of nano-TiO2

was assessed by the degradation of bromothymol blue in aqueous solution. Nano-TiO2 coated

on glass showed a higher photo-catalytic activity and self-cleaning effect that can effectively

be used in building envelops.

Fig 7: Nano-ilmenite.

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Dolomite-

SriLanka is rich with extensive deposit of dolomitic marbles with large quantities, which have

not yet been exploited on individual scale to produce value added product such as

precipitated calcium carbonate (PCC) nanoparticles. PCC is used extensively and its imported

by SriLankan industries for application as a filler and extender. Hence, this work attempts to

examine SriLankan impure dolomitic marbles as a source for the synthesis of pure nano

particles, so as to fulfill current industrial demand and to add value to the cheap and mundane

marbles. The calcium (Ca) components of the marbles can be extracted from impurities by

preparing solutions of saturated calcium hydroxide, calcium citrate, Ca2+ ethylene-diamine-

tetra-acetic acid complexes and calcium sucrate, separately from dolomite. PCC nanoparticles

are then synthesized by adding sodium carbonate to each calcium extract. The best extract to

synthesize PCC nanoparticles with high yield and purity is calcium sucrate. Here, calcium

sucrate has been used for surfactant assisted hydrothermal synthesis of PCC nanoparticles

with particle sizes ranging from 38.9 – 51.6 nm, which is a novel effort.

SriLankan dolomitic marbles can be used to synthesize PCC nanoparticles with high purity.

The extraction of calcium components of calcined dolomite to sucrose is the best way for the

preparation of PCC nanoparticles. Surfactants can be used to prevent the particle aggregation

during the preparation of PCC nanoparticles using calcium sucrate. The sucrate ions stabilize

calcite in the conditions favorable for aragonite. The synthesis of PCC nanoparticles for use in

local industries and for the export market is a good method to add a very high value to the Sri

Lankan dolomitic marbles.

Fig 8: Nano-Dolomite.

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Magnetite-

Toner is a main component of electro-photographic printing and copying processes. One of

the most important ingredients of toner is magnetite (Fe3O4) which provides the tribo-

charging property for toner particles. Nano- and micro-particles of Fe3O4 were synthesized

using the co-precipitation method and different amounts of lauric acid as a surfactant. The

synthesized nano and micro Fe3O4 was then used as the charge control agent to produce

toner by emulsion aggregation. The Fe3O4 and toner were characterized by X-ray powder

diffraction (XRD), atomic gradient force magneto-metry (AGFM), dynamic laser scattering

(DLS), particle size analysis, differential scanning calorimetry (DSC), and scanning electron

microscopy (SEM). The optimum amount of surfactant not only reduced particle size but also

reduced the magnetite properties of Fe3O4. It was found that the magnetite behavior of the

toner is not similar to the Fe3O4 used to produce it. Although small-sized Fe3O4 created toner

with a smaller size, toners made with micro Fe3O4 showed better magnetite properties than

toner made with nano Fe3O4.

Some studies attempts to synthesize magnetite nanoparticles from a high purity natural iron

oxide ore found in Panvila, Sri Lanka, following a novel top-down approach. Powder X-Ray

diffraction, elemental analysis, and chemical analysis data confirmed the ore to be

exclusively magnetite with Fe2+ :Fe3+ ratio of 1:2. Surface modified magnetite nanoparticles

were synthesized by destructuring of this ore using a top-down approach in the presence of

oleicacid. These oleicacid coated nanoparticles were further dispersed in ethanol resulting

instable nano-magnetite dispersion. Interestingly, the nanoparticles demonstrated a

spherical morphology with a particle size ranging from 20 to 50nm. Magnetic force

microscopic data was used to confirm the topography of the nanoparticles and to study the

magnetic domain structure.

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Table 02: applications of nanotechnology in SriLanka.

Applications of nanotechnology.

Examples.

Energy storage, production,

And conversion

Novel hydrogen storage systems based on carbon nanotubes and other lightweight nanomaterials.

Photovoltaic cellc and organic light emmiting based on quantum dots.

Carbon nanotubes in composite film coatings for solar cells

Nanocatalysts for hydrogen generation

Hybrid-protein-polymer biomimetic membranes

Agricultural productivity enhancement

Nanoporous zeolites for slow-release and efficient dosage of water and fertilizers for plants, and of nutrients and drugs for livestock

Nanocapsules for herbicide delivery

Nanosensors for soil quality and for plant health monitoring

Nanomagnets for removal of soil contaminants

Water treatment and remediation.

Nanomembranes for water purification, desalination, and detoxification Nanosensors for the detection of contaminants and pathogens

Nanoporous zeolites, nanoporous polymers, and attapulgite clays for water purification

Magnetic nanoparticles for water treatment and remediation

Ti02 nanoparticles for the catalytic degradation of water pollutants

Disease diagnosis and screening

Nanoliter systems (Lab-on-a-chip)

Nanosensor arrays based on carbon nanotubes

Quantum dots for disease diagnosis

Magnetic nanoparticles as nanosensors

Antibody-dendrimer conjugates for diagnosis of HIV-1 and cancer

Nanowire and nanobelt nanosensors for disease diagnosis

Nanoparticles as medical image enhancers

Drug delivery systems Food processing and storage

Nanocapsules, liposomes, dendrimers, buckyballs, nanobiomagnets, and attapulgite clays for slow and sustained drug release systems

Nanocomposites for plastic film coatings used in food packaging

Antimicrobial nanoemulsions for applications in decontamination of food equipment, packaging, or food

Nanotechnology-based antigen detecting biosensors for identification of pathogen contamination

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Air pollution and remediation

T1O2 nanoparticle-based photo-catalytic degradation of air pollutants in self-cleaning systems

Nano-catalysts for more efficient, cheaper, and better-controlled catalytic converters

Nanosensors for detection of toxic materials and leaks

Gas separation nanodevices

Construction

Nanomolecular structures to make asphalt and concrete more robust to water seepage

Heat-resistant nanomaterials to block ultraviolet and infrared radiation

Nanomaterials for cheaper and durable housing, surfaces, coatings, glues, concrete, and heat and light exclusion

Self-cleaning surfaces (e.g. windows, mirrors, toilets) with bioactive coating

Health monitoring

Nanotubes and nanoparticles for glucose, CO2, and cholesterol sensors and for in-situ monitoring of homeostasis

Vector and pest detection and control

Nanosensors for pest detection

Nanoparticles for new pesticides, insecticides, and insect repellents

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References-

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Nanoclays-and-their-potential-role-in-buidling-materials-and-services. (n.d.).

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Bridge, C. S. (n.d.). Technology Insight :