placement portfolio

PLACEMENT PORTFOLIO George Chousos

JULY 10, 2015 CARDIFF UNIVERSITY

Environmental Geoscience

Demokritos National Centre for Scientific Research

George Chousos Cardiff University C1263486

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Table of Contents:

Table of Figures: .............................................................................................. 1

Placement Learning Outcomes: ....................................................................... 2

Introduction: ................................................................................................... 3

Evidence of achievement of the learning outcomes: ...................................... 8

Placement Diary: ........................................................................................... 11

References: ................................................................................................... 29

Appendices: ................................................................................................... 30

Appendix 1: .......................................................................................................................................................... 30

Appendix 2: .......................................................................................................................................................... 31

Appendix 3: .......................................................................................................................................................... 32

Appendix 4: .......................................................................................................................................................... 37

Table of Figures: Figure 1. Map of Athens, Greece (www1)……………………………………………………………………………………….……..3 Figure 2. Map of the location of “Demokritos”, Ag. Paraskevi, Athens (www2)…………………………….……….3 Figure 3. Organization chart of “Demokritos”………………………………………………………………………………………..5 Figure 4. OC/EC instrument………………………………………………………………………………………………………………….11 Figure 5. Ion chromatographer…………………………………………………………………………………………………………….13 Figure 6. Particulate matter (PM) automatic measurement pumps………………………………………………………14 Figure 7. GC-FID instrument…………………………………………………………………………………………………………………15 Figure 8. Flow metre…………………………………………………………………………………………………………………………….18 Figure 9. Chemiluminescent Nitrogen Oxides Analyser, Model AC32M…………………………………………………18 Figure 10. A block of cement covered with a TiO2-infused layer of paint……………………………………………….19 Figure 11. Photocatalytic chamber……………………………………………………………………………………………………….19 Figure 12. GC 955, gas chromatographer………………………………………………………………………………………………20 Figure 13. The program edit menu of the GC 955 gas chromatograph……………………………………………………21 Figure 14. Custom-made photocatalytic chamber………………………………………………………………………………..23 Figure 15. Prototype photocatalytic chamber………………………………………………………………………………………23 Figure 16. Photocatalytic cement for NOx decomposition in cube form………………………………………………..27 Figure 17. Photocatalytic cement for NOx decomposition in powder form……………………………………………27


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Placement Learning Outcomes:

1. Enhanced my skills on teamwork, including communication and co-operation.

2. Development of my critical thinking on issues regarding the decisions that had to be made in the

laboratory.

3. Contribution to tasks that my supervisors assigned me to, such as taking part in the writing of a scientific

paper, as well as participating in labs’ chemical analysis procedures.

4. Broadening the horizons and expanding my knowledge on issues concerning air pollution and more

specifically on the concept of photo-catalysis.

5. Getting acquainted with the usage and the functionality of instruments specialised for recording and

measuring air pollution.

6. Enhancing my skills on researching for appropriate and beneficial bibliography and creating a thematic

library on the topic of air pollution.

7. Familiarized myself, by attending group meetings, with the procedures of distributing the tasks between

the members of the group.

8. Practised and developed my scientific speech by giving short lectures to students, discussing photo-

catalysis as a concept while presenting to them the instruments that are being used.

9. Improved my abilities of utilizing Microsoft Word & Excel through assignment given to me by my

supervisors.

10. I participated as co-author in one scientific paper that is to be submitted in a scientific journal and in 2

abstracts submitted to PAOT-3, the 3rd international conference for photocatalytic and advanced

oxidation technologies for the treatment of water, air, soil and surfaces that will take place in Gdansk,

Poland and EAC, the European Aerosol Conference in Milan, Italy.


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Introduction:

The National Centre for Scientific Research “DEMOKRITOS” (N.S.C.R. “Demokritos”) is the largest

multidisciplinary research centre in Greece, greatly focusing in the fields of Nanotechnology, Energy &

Environment, Biosciences, Particle and Nuclear Science, Informatics and Telecommunications. It’s

located at Agia Paraskevi, Athens,

Greece. The area is found on the foot

of Hemittos Mountain and it’s about

12 km to the north of the centre of

Athens (Fig 1, 2). “Demokritos” was

inaugurated in 1961 as a state-

owned entity under the name

Nuclear Research Centre, after the

nuclear reactor research facility

came into operation. That

innovation presented Greece with a

cutting-edge technology, which

indicated a major turning point in

the growth of large-scale research

infrastructures and the first step

towards the formation of a national

Research and Technology policy. In

1985 it took its present name and

became an autonomous Legal Entity of Public Law under the supervision of the General Secretariat for

Research and Technology (GSRT).

The primary aim of that newly established centre was the promotion of nuclear research and

technology for peaceful purposes. In that context, an opportunity was given for the repatriation of many

Greek scientists, who have contributed and continue to contribute to the development of the

Figure 1. Map of Athens, Greece (www1)

Figure 2. Map of the location of "Demokritos", Ag. Paraskevi, Athens (www2.


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infrastructure and the organisation of the scientific research and to provide the foundations for

postgraduate educational activities of the Centre. Furthermore, it conducts world-class basic and applied

research, for advancing scientific knowledge and to promote technological progress in selected areas of

socio-economic interest. The multidisciplinary of the scientific areas that are being treated in the same

area, such as physics, chemistry, microelectronics, biology, informatics, telecommunications, nuclear

technology, energy, radio-medicine, is unique and leads to scientific excellence.

The vision of “Demokritos” is mainly to become a source of Scientific Excellence & Innovative Ideas

in order to gain leadership as interdisciplinary, research Centre at European and also international level.

Its mission is to conduct high quality research in order to produce new knowledge and technology for

the benefit of the scientific and the social progress, to contribute to the diffusion of innovation into the

Greek society, to train high qualified young scientists, and to improve the strategic choices through

partnerships with research centres across the country and also abroad.

For the last, approximately, 50 years of operation, the Centre has contributed substantially to the

development and world-wide acknowledgement of the Greek research community, to the occupation of

new researchers at the implemented research projects and the expansion of about 40% of the Centre’s

dynamic. Furthermore, to the organisation of the first postgraduate programs in Greece (1963)

according to the international standards. During its years of action, always pioneering, boasts over 1500

doctoral dissertations, 500 trainings of secondary education teachers, 120 specializations of scientists in

radioisotope techniques, training of hundreds of Public Services and Organisations executives in

Computing during the 60s and 70s, about 2500 lectures to High School students and more than 5000

visitors annually. Lastly, the Centre has aided with the staffing of Greek universities, technological

institutes, research centres and private companies with scientists of excellence level.

As already mentioned above, the research centre’s orientation focuses mainly on thematic areas

such as Health, Biology & Biotechnology, Micro & Nanotechnology, Environment-Energy & Sustainable

Development, IT & Telecommunications, Nuclear Physics & Particle Physics, Nuclear Technology &

Radiation Protection, and Cultural Heritage, all of which are supported by the highest level of

postgraduate education. Those research areas are being coordinated by five research institutes;


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1. The Institute of Informatics & Telecommunications, which focuses mainly on the research

and development in the areas of Telecommunications, networks, web technologies and

intelligent systems.

2. The Institute of Biosciences and Applications, whose main characteristic is the

multidisciplinary biomedical and biotechnological research that relates to life sciences and

the environment and emphasizes on the development of, new molecules and biomolecules

for diagnostic and therapeutic use, on innovative nanomaterials and diagnostics for

medical and illustrative use, among others.

3. the Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, whose

activities are divided into four thematic areas; Energy/Environment Technologies & Safety,

Nuclear Technology, Bio-diagnostics, and Radiological Sciences and Radio-pharmaceutics.

4. The Institute of Nanoscience and Nanotechnology, which increases the European

competitiveness of the country in Key Enabling Technologies, such as nanotechnology,

micro- and nano-electronics and photonics and lastly,

5. The Institute of Nuclear & Particle Physics, focusing on research areas, such as particle

physics, nuclear physics, astrophysics-cosmology and grid computing.

Figure 3. Organization Chart of "Demokritos"


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Figure 3 shows a clear representation of the organisational structure of the National Centre for Scientific

Research “Demokritos”.

The institute where my work placement took place was the Institute of Nuclear & Radiological

Sciences & Technology, Energy & Safety. As already mentioned above the institute is divided into four

thematic areas, one of them being the Energy, Safety and Environmental Technologies. Amongst the

areas of air quality and climate change studies, in which I was participating, other activities of the division

are solar energy systems, alternative fuels and energy carriers, dioxin and dioxin-like compounds analysis

and human exposure assessment.

The main research being conducted in the objective of air quality is to determine air pollution from

airborne particulate matter (PM), to assess the indoor/outdoor air quality and also pollutants emissions

from industries, including the measurements of the physical properties and chemical analyses of

ambient particulate matter, volatile organic and inorganic compounds etc. In addition, studies are being

carried out on innovative photocatalytic materials for the purpose of removing/oxidizing air pollutants

in the urban and indoor environment.

One of the contributing laboratories in the division is the Environmental Research Laboratory. Its

main goal was to produce scientific know-how and innovative tools suitable for research in the fields of

environment and energy. Equipped with modern facilities for air pollution and gas sorption

measurements, it provides high-level of services on matters such as atmospheric modelling, gas storage

and environmental impact assessment.

My principle role was that of the scientific researcher/laboratory assistant and my duties within the

organisation were to contribute at the chemical analysis of atmospheric particulate matter (PM2.5,

PM10). More specifically, I trained in the analysis of:

1. OC/EC (organic/elemental carbon) using an OC/EC aerosol analyser with a proven thermal-

optical method. More specifically, the method for measuring elemental and organic carbon

in ambient particulate matter (PM) samples deposited on filters is based on the volatilization

and oxidation of carbon-containing PM components. The procedure described is a thermal-

optical transmittance/reflectance (TOT/TOR) method. For the analysis, tissue quartz filters

are used, while EUSAAR2, NIOSH870 or IMPOVEA protocols are followed.


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2. Ions (anions, cations) using IC (ion chromatography) system DIONEX 1100 & DIONEX 5000.

As far as the chemical process is concerned, tissue quartz filter becomes subjected to

ultrasonic extraction, using 6 ml of nanopure water and 0.5 ml isopropanol. Then, the

solution is injected to the ionic chromatographer.

3. Volatile Organic Compounds (VOCs), such as toluene, benzene, ethylbenzene, etc. using gas

chromatography. The instrument used for the procedure was a GC (gas chromatography)

Agilent 6890N equipped with an FID (flame ionization detector), a thermal desorption unit

and a cryotrapper (GERSTEL TDS3).

4. I was familiarised and trained with the photo-catalysis instrumentations. Photocatalysis is

the acceleration of a chemical reaction, e.g. oxidation, by the use of light. It was first found

in 1972 by the pioneers Fujishima and Honda, who succeeded the photocatalytic splitting of

water into its elements. The scope of the current experiments was to estimate the ability of

photocatalytic materials to eliminate air pollutants. Tests were performed in special design

photocatalytic reactors. More specifically, we used three different photo-catalytic gas

chambers for the tests, two of which were custom made at “Demokritos” for the analyses

and one brought to us by Salentec slr. Company as a prototype. The rest of the equipment

include building materials covered with titanium dioxide (TiO2), such as white cement,

ceramic tiles, UV lamps and various types of pollutant gases, e.g. nitrogen oxides (NOx) and

a mixture of benzene, toluene, ethylbenzene and xylenes (BTEX).

Following the training from the laboratory experts as well as the SOPs (Standard Operating

Procedures) of each of the above methods, I managed to sample, handle and chemical characterize a

significant number of atmospheric samples.

Lastly, I performed a state of the art study on the science field that the laboratory is involved. More

specifically, I extensively scrutinised the scientific articles of the lab personnel and in addition a

significant number of articles in the field of atmospheric pollution and its remediation.

My immediate supervisors throughout my placement at the Centre were Dr. Thomas Maggos and

Dr. Dikaia E. Saraga.


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Evidence of achievement of the learning outcomes:

Regarding the enhancement of my teamwork skills, e.g. communicating, critical thinking, co-

operating, etc. during the group meetings the task, which was assigned to me, was to be involved in the

OC/EC chemical analysis of PMs. The current task was part of a European project which was allocated to

the lab from CEN, the European Committee for Standardization. The duration of the project was one

year, starting from January till December of 2014. I joined the project around September and I

contributed to the 51% of the total filters chemical analysis (approximately 600 filters).

Another learning outcome during the placement was my contribution on the writing of a scientific

paper and also the enrichment of my knowledge on issues concerning air pollution. I was involved in the

introduction of the paper. For that purpose I had to scrutinize a number of published papers in order to

include as much information as possible. The main subject of my research, and also the topic of the

paper, was on particulate matter (specifically PM2.5) measurements and polycyclic aromatic

hydrocarbons (PAHs) characterization in ambient air. After going through the papers, I gathered up the

information required to write the introductory part of the paper and composed some drafts. With the

guidance of my supervisor, I eventually picked the best one for the paper and submitted it to her.

Going through scientific papers of various topics regarding air pollution issues for both my

knowledge enhancement and for the needs of the tasks that I was assigned to complete, I created a

literature library, an example of which can be seen in Appendix 3, in order to categorize the topics for

my convenience.

A summary of the information collected throughout the year is given below:

An air pollutant is a substance that can have adverse effects on humans and the environment. The

substance can be solid particles, liquid droplets or gases and can be originated either naturally or by

human interference. The main air pollutants that are considered harmful or can have poisonous effects

are:

Particulate matter (PM): a complex mixture of extremely small particles and/or liquid droplets.

Particle pollution is mainly made up of a number of components, such as organic chemicals,

metals, and soil or dust particles. They can be split up into three different groups, depending on

their size; coarse particles (<10 μm), fine particles (<2.5 μm) and ultrafine particles (<1 μm).


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Particles smaller than 10μm are thought to pose the greatest problems, since they can penetrate

deep into the lungs, thus creating various respiratory problems.

Volatile organic compounds (VOCs): the principle pollutants are benzene, toluene, ethylbenzene

and xylenes. They are emitted as gases for certain solids or liquids. Typically the concentration

of these pollutants are higher (up to ten times) in indoor environments than outdoor. A vast

variety of products emit volatile organic compounds, such as paints and lacquers, cleaning

supplies, pesticides, building materials, copiers and printers, etc. Health effects include eye, nose

irritation, headaches, nausea, damage to vital organs, e.g. kidney, liver.

Nitrogen oxides (NOx): recognised as a highly reactive group of gasses, most of which are

emitted into the atmosphere in the form of nitrogen monoxide (NO) and nitrogen dioxide (NO2),

which can contribute to the formation of ground-level ozone (O3) by reacting with VOCs under

sunlight. Their main sources are combustion, tobacco smoke, cars and power plants. Health

problems include respiratory deterioration.

Ground-level ozone (O3): as mentioned above, ground-level ozone is mostly emitted into the air

by chemical reactions between nitrogen oxides and volatile organic compounds in the presence

of sunlight, but it can also be emitted directly from copiers, printers and screens. It can trigger a

variety of health problems, especially for children, the elderly and people suffering from lung

diseases, e.g. asthma.

Sulphur dioxide (SO2): an additional group of reactive gasses. Their major sources are power

plants, industrial facilities and processes such as the extraction of metal ores and the burning of

high sulphur containing fuels by large ships, locomotives, etc. Linked to a number of adverse

effects on the respiratory system.

For the treatment of such gas pollutants various air pollution control and purification techniques are

available. One of these techniques, and the one being tested in the laboratory, at “Demokritos” Centre,

is photocatalysis. As already mentioned, photocatalysis is the acceleration of a chemical process in the

presence of light. The basic requirements for photocatalysis to occur are the presence of:

A photocatalyst, a semiconductor material, such as metal oxides (ZnO, TiO2, CdS, etc.). TiO2 is

the most predominant, compared to the rest, due to its superior characteristics, e.g. low cost,


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very stable (inert), low or no toxicity, activation in environmental conditions (low energy costs),

etc.

A liquid or gaseous intermediate

Irradiation, usually ultraviolet (wavelength <400 nm)

Once the semiconductor becomes irradiated with UV or visible light, a series of redox reactions occur on

the surface of the semiconductor, which in turn produce highly reactive oxidants. Subsequently, the

oxidants created on the surface come in contact with the gas molecules that are adsorbed and

decompose them into harmless for the environment compounds. Moreover, the photocatalytic process,

using TiO2, is not isolated in decomposing air pollutants, but has expanded into various applications, such

as the development of, self-cleaning and anti-fogging surfaces, antimicrobial action, water treatment,

etc.

During the 28th week of my placement, we were joined by two high school students who were

placed under my custody for the entire week. My main responsibility was to acquaint them with the

instruments in the laboratory, including their utility and usage, the projects we were taking part in and

the main concepts of air pollution and its remediation, e.g. particulate matter, photocatalysis etc., which

comprised of the improvement of my scientific speech and my ability to communicate my knowledge.

Furthermore, I was also trained and thus expanded my knowledge and ability to use Microsoft

Word and Excel. Throughout my placement I was given instructions to create either paragraphs meant

to be used in research papers or reports in Word or produce graphs and diagrams in Excel for the same

purpose.

Lastly, I had the opportunity to work with my team on two abstracts, thus placing my name in the

list of authors. The first one referred to the chemical characteristics of traffic related particles and the

effects on human health. The abstract was sent to the European Aerosol Conference (EAC) 2015

Scientific Program Committee for evaluation and eventually it got accepted, and which will be presented

as a poster at the Milan conference for Atmospheric Aerosols-Specific Aerosol Types (Appendix 1). The

second abstract’s subject was the investigation of the photocatalytic activity of doped titania nano-

powders under the irradiation of visible light. The abstract was submitted to the 3rd international

conference of photocatalytic and advanced oxidation technologies in Gdansk (Appendix 2).


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Placement Diary:

1st week (08-12/09/2014):

The first week of my placement in “Demokritos” was the introductory week. I familiarised with my

colleagues, the environment in the laboratory, the instruments which I will be using later on in the

placement, and any relevant projects that I

would take part of. I was shown to my first

instrument, which was the OC/EC

(organic/elemental carbon) aerosol

analyser (Fig 4). This instrument is being

used to measure the organic and elemental

carbon concentration in ambient

particulate matter (PM), specifically PM2.5

and PM10, samples deposited on quartz

fibre filters, a procedure described as

thermal-optical transmittance/reflectance method. I studied thoroughly its manual so I could have a

better understanding of its utility and usage. At first, I was only observing the process of taking the

measurements, i.e. changing of the filters, taking notes, etc.

In addition, I was presented with the project that I was going to be a part of. The project originated

from CEN, the European Committee for Standardization, an association that unites the National

Standardization Bodies of 33 European countries. It’s one of the three organizations that have been

recognised, by the European Union and by the European Free Trade Association (EFTA), for developing

and defining voluntary standards at European level. Its activities relate to a vast variety of fields and

sectors, one of them being the environment (CEN, European Committee for Standardization, 2015). The

main goal of the project was to investigate the practicality and feasibility of the performance

requirements, criteria and QC (quality control) checks proposed in prEN/TS 16450:2012 for the

appropriate operation of PM Automated Continuous Measurements Systems (AMS) under practical field

conditions. The task that our laboratory undertook was the analysis of the filters from four different sites

Figure 4. OC/EC instrument.


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all over Europe, Italy, Germany and two from the Netherlands. With the utilization of the instrument

mentioned above, three candidate methods were evaluated (EUSAAR2, Improve and NIOSH870). The

project lasted for one year and the number of analyses was, in total, 1063.

Lastly, they showed me how to search for appropriate and useful literature for the purpose of

assisting in any of the research conducted, which also led to the enrichment of my own knowledge on

the subject.

2nd week (15-19/09/2014):

In my second week here, after observing my mentor, I started operating the instrument myself

under her supervision. As already mentioned, I took part in the writing of a scientific paper which topic

was on particulate matter measurements and polycyclic aromatic hydrocarbons characterization in

ambient air in an apartment in Greece. The experimental part of the paper was conducted under

different activities scenarios, such as smoking, grilling, frying, etc. My main task was to compose the

introduction of the paper including information about emissions of PM2.5, PAHs, their effects on the

environment and their emission sources. The writing of the paper has yet to be completed and it is still

under process.

3rd week (22-26/09/2014):

During the third week of my placement I was introduced to my next instrument, the Ion

Chromatographer (Fig 5). This is used to measure the cations (e.g. Na+, K+, Ca+) and anions (e.g. F-, SO4

2-,

NO3-) of liquid samples in order to figure out their composition and the origin of the sources. Throughout

the week I was in charge of both the OC/EC and the Ion Chromatographer simultaneously.


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Moreover, my mentors and I started working on a campaign, conducted in my office. The aim was

to investigate possible emission of ozone (O3)

from an air purifier. Continuous measurements

of O3 concentrations were conducted using an

ozone automatic thermo analyser instrument-

i30. In addition, a Grimm 1.108 automatic

spectrometer instrument was utilized in order

to monitor the particle distribution in the room,

every day in the course of a week. My input at

the campaign was to monitor the

instrumentation, record the alternations in the

mode of the air purifier, i.e. quiet, medium,

high, and turbo and after the experiment was over I was in charge of creating representable diagrams,

from the results, which were used in the final report.

4th week (29.10-03.11/2014):

The first two days of the fourth week, my mentor and I calibrated the OC/EC instrument. The

reason why the calibration had to be done was due to the fact that the gases, which are being used by

the instrument, were replaced and thus making the gas flows unstable. Given the fact that the process

regarding the gases is very delicate, they had to be in balance prior to the usage of the instrument. Once

it was over we continued with the filters. At the end of the week, I was asked to contribute to the

installation of PM samplers (Fig 6), at a central building on Mesogeion Avenue, one of the main roads in

Athens at the eastern suburbs, for the needs of an experimental campaign. My contribution in the above

campaign offered me experience in their function and utility.

Figure 5. Ion chromatographer.


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5th week (06-10/10/2014):

During the fifth week of the placement, my main

responsibility was to handle the OC/EC instrument, since the

samples for the Ion Chromatographer were finished the week

before. At the meantime, I was also doing my research on the

introduction I was writing for the paper, composing some

drafts that were later on submitted to my mentor for review

and evaluation.

6th, 7th & 8th week (13-31/10/2014):

In the course of those weeks, my obligations were similar

to the fifth week; continuing with the measurements of the

filters for the CEN project, with only difference that I was

trusted to conduct the experiment on my own on the eighth week, except of Tuesday since it was a

National Holiday, because my mentor was absent. In addition, the writing of the introductory part of the

scientific paper came to an end as I submitted the final product to my mentor for her to include in the

paper.

9th week (3-7/11/2014):

In the ninth week, the third portion of the filters came to an end, for the OC/EC analysis, thus

receiving the fourth and final portion of the campaign. Moreover, I was advised to research on the topic

of volatile organic compounds (VOCs), such as toluene, benzene, ethylbenzene etc., so I can acquaint

myself on the subject and be introduced to the corresponding instrument.

Figure 6. Particulate matter (PM) automatic measurement pumps.


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10th week (10-14/11/2014):

As mentioned above, this was the week I got presented to the instrument measuring VOCs in

ambient air, the GC-FID (gas

chromatograph) (Fig 7). The method

used to determine the VOCs is the EN

ISO 16017. The equipment used to

measure the VOCs are small glass

tubes adsorbents, with a 6mm outer

diameter (OD), a 4mm inner diameter

(ID) and about 177.8 mm in length.

The tubes are filled with Tenax TA

(polydiphenyl oxide). During my time

in the lab, the experiments conducted

were only for calibrating the

instrument, whose procedure was to spike in the glass tube, using a 10 μl syringe, 1μl of the appropriate

standard solution and subsequently placing it, for 30 minutes, at a pouring unit through which pure inert

helium (He) is being imported at flow rates of about 100 ml/min. It should be noted that, before the

spiking, the syringe is cleaned, about 15 times, using methanol. The analysis of the VOCs is performed in

a thermal desorption unit coupled to GC-FID. The tubes are heated up to 240oC for 10 minutes and the

desorbed compounds were transferred to a capillary cryogenic trap held at -100oC. The cryogenic trap is

then ballistically heated up to 200oC and the compounds are injected to the analytical column.

11th week (17-21/11/2014):

This week’s main responsibility was to continue the measurements of the filters of the CEN

campaign. At this point in the placement, I had a lot of experience running the instrument on my own,

thus having no supervision from my mentors, except for the daily update on the progress of the

measurements, until the deadline of the campaign. At the end of the week I submitted my placement

progress report to Cardiff University.

Figure 7. GC-FID instrument.


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12th, 13th & 14th week (23.11-12.12/2014):

In the course of these weeks my tasks were limited to handling the OC/EC instrument important

for the CEN campaign, again unsupervised, and also observing and assisting with the calibration of the

GC-FID, responsible for the VOCs measurements. In the meantime, one of my mentors gave me

published scientific papers of the lab personnel and in addition a significant number of articles in the

field of atmospheric pollution to study.

15th week (15-19/12/2014):

In the fifteenth week, the filters send to us for the OC/EC instrument came to an end, thus

concluding the campaign for the European Committee for Standardization (CEN). The final step we

carried out was to gather and organise the data collected throughout the year and send it to them for

evaluation and for the continuation of their research. The only occupation left for me in the lab was the

calibration of the gas chromatographer.

16th week (22-24/12/2014):

The sixteenth week in Demokritos was mainly spent on me researching into scientific papers and

journals, since it was the week before Christmas, therefore not having any campaigns or tasks assigned

to me.

The period from the 25th of December until the 8th of January marked our Christmas vacation.

17th week (09/01/2015):

On my return to the Centre I was announced that I would be introduced to the concept of photo-

catalysis, and I was also given some of the papers of the lab personnel on photocatalysis so I would

familiarize myself before I would be properly introduced to the instruments.


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18th & 19th week (12-21/01/2015):

During the first two weeks after the Christmas break, to prepare for my introduction to

photocatalysis, I requested from my mentors to give me any material, such as books, journals and

scientific papers, they had about the concept of photocatalysis.

From the 22th till the 31st of January I travelled to Cardiff, having permission from my mentor to do so,

where I met with my mentor Dr. Tim Jones to discuss some inquires about my dissertation and to start

researching on the topic that I chose. We discussed my decision on changing the previous idea I had

considered for my 3rd year dissertation plan, which was air pollution in Athens and its consequences on

human health to writing about photocatalysis as a method of purifying polluted air and its applications.

20th & 21st week (02-13/02/2015):

Throughout those two weeks of my work placement in “Demokritos”, my main task was to

meticulously research on the concept of photocatalysis, which I achieved by scrutinizing scientific papers

and books both from the lab’s personnel and from papers found online. In that period of time I was able

to comprehend the idea of photocatalysis and have had a better understanding of the theoretical part,

thus requesting from my mentor to introduce me to the instruments and to the experimental part. In

addition, there was an issue with the OC/EC instrument, which didn’t allow us to analyse any filters.


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22nd & 23rd week (16-27/02/2015):

In the course of these weeks, I was introduced to one of the equipment used in the experiments

in photocatalysis. As seen in Figure 8, I was acquainted

with the flow metre. The flow metre is mainly used to

adjust the flow of the gases that are being used in each

experiment, i.e. control the concentration of the

desirable gas that flows into the photocatalytic

chamber, e.g. synthetic air, nitrogen oxides (NOx),

volatile organic compounds (VOCs) etc., and in some

cases to create a combination of gases. It was fairly

simple to understand the function and utility so we

began testing the flows. The tests were conducted

with the help of the Chemiluminescent Nitrogen

Oxides Analyser Model AC32M (Fig 9), by

connecting a teflon tube from the flow metre to

the analyser, from which the gases flew. Main

applications of the analyser are monitoring

nitrogen oxides (NO2, NOx and NO) in ambient

air. The typical levels of concentration measured

range between 0.4 ppb to 20 ppm. In our

experiments the concentration we tried to

achieve was at about 350 ppb.

Figure 8. Flow metre.

Figure 9. Chemiluminescent Nitrogen Oxides Analyser, Model AC32M.


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After the stabilisation of the gas flows the photocatalytic experiments initiated. The main idea behind

the concept of photocatalysis is the treatment, with the use of a semiconductor, in this case titanium

dioxide (TiO2), and with UV irradiation, of air

pollutants such as nitrogen oxides (NOx, NO2,

NO) and volatile organic compounds, e.g.

benzene, toluene, ethylbenzene etc. The

semiconductor, i.e. the titanium dioxide (TiO2),

was impregnated onto the surface of a building

material, such as cement, ceramic tile, glass

etc. (Fig 10). Once the pollutants are adsorbed

on the surface of the semiconductor and the

material is subjected to UV light,

photocatalysis activates, thus degrading the

pollutants and decreasing their concentration.

The chamber used for the experiment can be

seen at Figure 11.

As already mentioned, the concentration level

we picked for our gases was at approximately

350 ppb. The procedure was throughout the

experiment the same. Firstly, we let the gas

flow through the chamber to stabilise, without

placing any building material in or UV

irradiation. Then we turned on the UV lamps

and left it for about 30 min to 1 hour. A slight

decrease was noticed. Secondly, the building

material was placed in the middle of the

chamber without the activation of the UV lamps. About the same result; a decrease in the concentration

Figure 10. A block of cement covered with a TiO2-infused layer of paint.

Figure 10. GC 955, gas chromatograph.Figure 11. A block of cement covered with a TiO2-infused layer of paint.

Figure 11. Photocatalytic chamber.


20

of the pollutant was observed. Lastly, including both the material and the UV lamps in the experiment

the concentration decreased and the degradation rate (μg/m2s) and percentage (%) were calculated.

24th & 25th week (02-06/03/2015):

During the first day of the twenty-fourth week I was introduced to another of the equipment used

in the photocatalysis experiments, the GC955 a gas chromatograph for automatic measurements of

compounds in air and other gas mixtures (Fig 12). In our experiments it was used to measure the

concentration of some volatile organic compounds, such as benzene, toluene, ethylbenzene and xylenes

(BTEX). Since it was a new instrument neither my mentor nor I knew how to operate it, so an expert on

the instrument came and trained us on its utility. The training lasted about one hour and it included

information on how the measurement is being taken, what is the procedure before we receive the data,

how to retrieve the data we require and how to calibrate the instrument. Throughout the rest of the

weeks, after being trained on the utility of the instrument, we decided to start running some

experiments to comprehend the practical part.

Figure 12. GC 955, gas chromatograph.


21

The default measuring process, which can be seen in Figure 13, of the instrument consists of cycles of

15 min duration each. During each cycle, in 3 min intervals, i.e. sample strokes, a portion of the gas is

injected into the instrument (about 4-5 ml). The total amount of gas measured is 20 ml per cycle. Once

the 15 min cycle is over, the subsequent one initiates and, simultaneously, the analysis of the sample

that was preconcentrated in the last run begins.

In the beginning of our experiments, we decided to change the default sampling process to inject

the whole amount of the desirable gas, which was during the 3.5-5 min instead of the 3 min intervals.

The results showed that the concentration of the pollutants measured, using our method, were less than

half of the expected concentration, thus forcing us to restore its default sampling mode.

During week 25 of my placement, we continued the experiments on photocatalysis while using the

nitrogen oxides (NOx) as the desirable pollutant. As already mentioned the concentration level we chose

Figure 13. The program edit menu of the GC955 gas chromatograph.


22

was at about 350 ppb. For all the duration of the experiment, which was 3 days (10th, 11th and 12th), the

experimental process remained constant; the gas would flow through the photocatalytic reactor with

UV irradiation and in the absence of a TiO2- infused building material, then we would add the material

but turn off the UV lamps and finally have both the lamps and the material concurrently. The expected

result would be for the concentration to decrease drastically in the presence of the UV irradiation and

the material, in contrast to our results, where they either remained constant or increased slightly. In

addition to this, we decreased the initial concentration to about 145 ppb, in case the original level was

too high, but the results remained constant.

26th, 27th & 28th week (16.03-03.04/2015):

Throughout the course of those three weeks my main task was to enhance my knowledge on the

concept of photocatalysis, both for the placement and the experiments I would conduct and for my own

dissertation, by scrutinizing several scientific papers. I was also given, to study, the doctoral thesis of my

mentor in “Demokritos”. In the 28th week we were joined by two high-school students for the duration

of the week. They were assigned to me to familiarize them with the lab personnel, the topics of research

in the laboratory, the instruments being operated, and lastly I lectured them on the concept of

photocatalysis, explaining the chemical process and its environmental effects.

The period from the 6th till the 14th of April marked our Easter holiday.

30th week (15-17/04/2015):

Similar to the previous weeks I was going through scientific papers in order to comprehend the

subject of photocatalysis, mostly the chemical processes that take place and the mechanics of the

procedure.


23

31st week (20-24/04/2015):

On the first day of the thirty-first week two new photocatalytic chambers were delivered to us.

The first one, as seen in Figures 14 and 15, is a prototype photocatalytic chamber, for testing, sent to us

from Salentec S.L.R, a company from Italy established in 2005 (Salentec advanced technologies, n.d.).

The instrument is compliant with the UNI 11484 -2013

standard; a method to determine the ability of inorganic

materials spread either in cementitious mortars, and/or

lime-, ceramic matrices, paints or deposited as thin films or

coverings onto various substrates to remove nitrogen

monoxide (NO) from a gas stream by photocatalytic action.

(UNI ente Italioano di normazione, n.d.). The second

photocatalytic chamber (Fig 16), is a custom made chamber,

produced in “Demokritos” Centre, for the purposes of

conducting photocatalytic tests. The second one was mostly

operated by a university student, from the National

Technical University of Athens, that joined us in order to conduct the experiments he required. The

Figure 14. Prototype photocatalytic chamber.

Figure 15. Custom-made photocatalytic chamber.


24

experiments carried out, on the 23rd and 24th while using the latter photocatalytic chamber, were much

more encouraging than the previous ones. The desired gas pollutants were benzene, toluene,

ethylbenzene, p-xylene and o-xylene, all of which are volatile organic compounds. Even though the

concentration of benzene did not decrease considerably, expected because of its high chemical stability,

the results showed an immense degradation rate for the rest of the pollutants over the course of

approximately four hours.

32nd week (27.04-01.05/2015):

In the start of the thirty-second week of my placement, the gases that were used for the

photocatalytic experiments run out, thus having to wait until the new ones would arrive. On the 28th of

April, the Centre hosted a lecture, given by Professor Gregory V. Korshin from the University of

Washington, Department of Civil and Environmental Engineering, at the Institute of Nanoscience and

Nanotechnology. The topic of the speech was the “Use of Absorbance and Fluorescence Spectroscopy in

Examining Mechanisms and Predicting the Efficiency of the Degradation of Emerging Contaminants in

Advanced Oxidation Processes”. My mentor advised me to attend to the lecture, as it was relevant to

the research I had been doing at the Centre.

Throughout the rest of the week, Dr. Dikaia Saraga and I started writing the final report for the CEN

campaign. The report consisted of the data that were gathered during the year, i.e. the measurements

of the organic and elemental carbon on the filters, presented as graphs and of a writing section clarifying

the above data. My responsibility in the preparation of the report was to gather up the data from the

instrument, separate them into appropriate sections and create the desirable Excel graphs.

33rd week (04-08/05/2015):

On the first day of the thirty-third week, I had already finished the graphs they asked me to create

so I submitted them to my mentors, thus concluding my part of the contribution, to the report. Since the

report was my only responsibility, I started composing my placement portfolio. I consulted my mentors

in aiding me with the preparation of my portfolio, especially on creating an appropriate structure and

the information I was going to write. On Wednesday, the 6th of May, my mentor, Dr. Thomas Maggos,


25

gave a lecture at the National and Kapodistrian University of Athens to the postgraduate students of the

university. The topic of the two hour lecture was “Photocatalytic decomposition of air pollutants using

building materials enriched with titanium dioxide”. I was advised to attend the lecture, since that was

also the subject of my research, both for my university dissertation and for the research in my placement.

The last two days of the week were consisted of research on photocatalysis and the writing of the

portfolio.

34th week (11-15/05/2015):

On the 11th and 12th of May, my two main tasks were to continue writing my portfolio, while

consulting my mentor in order to get some assistance with it, and to do some more research on the

concept of photocatalysis, by going through scientific papers either given to me from the lad personnel

or from journals that I found on-line. While I was enriching my own knowledge on photocatalysis, by

scrutinizing the papers, I was also keeping a journal including all the information that I could use for my

own third-year dissertation for my university. In addition to the tasks already mentioned, for the rest of

the week, I was asked once more to contribute to the writing of the CEN report. Since I was not eligible

to write the report, my contribution to the report was to gather up the rest of the data from the OC/EC

instrument and use Excel to create the graphs requested.

35th week (18-22/05/2015):

Continuing from the previous week, the first three days of this week consisted of me creating the

graphs for the CEN report, while consulting my mentors to confirm that the graphs were accurate.

Another responsibility of mine, besides creating the graphs, was to produce a fitting caption for each

graph describing the results shown, the method being used, and the city or area that the filters were

sent from. For the rest of the week, I focused my attention on writing the rest of the portfolio and doing

research on photocatalysis.


26

36th & 37th week (25.05-05.06/2015):

Photocatalytic experiments were aborted as we had to order the appropriate tubing connections

and consumables (e.g. gasses) in order to set the new photocatalytic reactor .Throughout the rest of the

week, since I couldn’t go through with any tests, my main concern was the continuation of the portfolio.

Same as the previous week, during the 37th week my main obligation was to write my portfolio, while

doing more research on photocatalysis, by reading journals and published papers. In addition to this, I

was also assisting some of the personnel in the lab in any way they needed.

38th week (08-12/06/2015):

On the 8th of June all of the equipment necessary for the assembly of the photocatalytic

experiments were gathered so we spent the day fixing and putting together the pieces. After finishing,

we had to wait for the gas pollutants and for one more instrument to arrive. For the rest of the week, I

continued searching and scrutinizing scientific papers for photocatalysis and I also assisted at the OC/EC

instrument by running some of the filters they were sent from Qatar.

39th week (15-19/06/2015):

On the first day of the 39th week, I was announced, by my mentor, that I would give an

approximately 30-min PowerPoint presentation of my learning achievements throughout my year in the

Centre. The presentation would take place on my last day of work and it would be in front of the lab

personnel I worked with, including both of my mentors and the Director of the institute Dr. Athanasios

Stubos. As it was my first time giving an oral presentation I asked from my mentor, Dr. Dikaia Saraga to

send me any presentations she had already given to assist with mine. In addition to that, I also employed

Dr. Thomas’ Maggos presentation, at the National and Kapodistrian University of Athens a couple of

weeks ago, to create my own. For the rest of the week, I focused my attention on composing the

presentation while doing some more research on photocatalysis and writing the rest of the portfolio. On

the last day of the week, we were finally ready to start conducting the photocatalytic experiments, as all

of the apparatus essential for the tests had arrived.


27

40th & 41st week (22.06-03.07/2015):

Throughout those two weeks my main

responsibilities in the lab were, the

photocatalytic experiments supervised by my

mentor, my individual research on

photocatalysis, writing the portfolio and

creating my PowerPoint for my presentation.

For the photocatalytic experiments we used

building materials, such as cement, infused with

titanium dioxide (TiO2) for the nitrogen oxides

(NOx) decomposition. Two different forms were

used; one was as powder and the other as a

cube, as seen in figures 16 and 17 respectively.

The experiments run daily, changing the material

inside of the photocatalytic chamber (Fig 11) for

each test, while the duration of each one was

around 4-5 hours. The desired concentration of

the pollutant was about 350 ppb and the

instrument used was the Chemiluminescent

Nitrogen Oxides Analyser (Fig 9). After the

finishing of each test, my task was to collect the data from the apparatus, load them on Excel and create

graphs in order to ascertain the fact that photocatalytic decomposition of the gas pollutants occurred.

Furthermore, I performed calculations, based on appropriate equations for the quantification of the

photocatalytic removal of the gas pollutants. Then, I presented the results of the tests to Dr. Thomas

Maggos for evaluation. An outcome of the experiments was that although in both cases decomposition

of the nitrogen oxides occurred, a higher degree was observed while using the powder form.

Figure 17 Photocatalytic cement for NOx decomposition in powder form.

Figure 16. Photocatalytic cement for NOx decomposition in cube form.


28

Moreover, I was preparing my presentation of the overall work and achievements during my time

at the Centre, with the help of my mentor. The research and the reading of scientific papers was put on

hold, in order for me to focus on the more significant tasks at that point, e.g. next week’s presentation.

42nd week (06-10/07/2015):

The 42nd week consisted the last week of my work placement at the National Centre for Scientific

Research. For that reason, my tasks and responsibilities were limited to finishing the writing of my

portfolio and the presentation taking place at the end of the week. In addition, the photocatalytic

experiments also were put on hold, due to the fact that one of our gas bottles, containing synthetic air,

run out thus preventing the tests to continue. On Wednesday 8th of July, I submitted my portfolio to my

university, thus leaving me with my only responsibility being the presentation and its preparation. For

the last two days, I spent them working on the presentation and finally on Monday 13th I gave the

presentation to the personnel in the lab and my two mentors, thus ending my time and work placement

at the Centre.


29

References: CEN, European Committee for Standardization, 2015. What we do. [Online] Available at: https://www.cen.eu/work/Pages/default.aspx [Accessed 30 June 2015]. Salentec advanced technologies., n.d. About us: Spin off. [Online] Available at: http://www.salentec.com/salentec/profilo.aspx?idPagina=106 [Accessed 30 June 2015]. UNI ente Italiano di normazione, n.d. UNI Standard. [Online] Available at: http://store.uni.com/magento-1.4.0.1/index.php/uni-11484-2013.html?___store=en&___from_store=it [Accessed 30 June 2015]. WWW1: Google Earth, 2014. Map of the National Scientific Research Centre "Demokritos" 38o00’12.97”N, 23o49’31.09”E, elevation 265m. 3D Buildings data layer. WWW2: Google Earth, 2014. Map of Athens, Greece, 37O59’37.87”N, 23O49’14.63”E, elevation 381m. 3D buildings data layer.


30

Appendices:

Appendix 1: Chemical characteristics and health risk assessment of traffic related particles

St. Pateraki1, K. Bairachtari1,2, C. Markellou3, G. Chousos1, Α. Stamatelopoulou1, N. Mihalopoulos3,4, Ch.Vasilakos1 and Th. Maggos1

1 Environmental Research Laboratory/ I.N.RA.S.T.E.S., National Centre for Scientific Research “DEMOKRITOS”, 153 10 Aghia Paraskevi, Athens, Greece

2 Hellenic Army Academy, Division of Physical Sciences & Applications, Vari Attica 16673, Greece

3 Environmental Chemical Processes Laboratory, Chemistry Department, University of Crete, 2208, 71003

Heraklion, Greece 4 Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Palaia Penteli, 152 36, Athens, Greece

Keywords: Fine particles, roadside, chemical composition, health risk assessment

Presenting author email: [email protected] Roadside air quality in cities is an environmental and simultaneously health issue of increasing concern, especially in urban areas where many roadways are lined by dense and high-rise buildings forming street canyon that greatly limits the dispersion of mobile emissions. Recently, the WHO classified diesel exhaust as Group I Carcinogen (Rakowska et al., 2014) while aerosol samples taken in urban areas show that motor vehicular emissions, especially diesel exhausts, constitute the most significant source of ultrafine and fine particles (Lee et al., 2006). Despite the implementation of emission control programs, roadway transport is still a major source of PM pollution (Rakowska et al., 2014). In general, horizontal aerosols profile in a roadside microenvironment has been studied extensively. Unfortunately, there are only limited studies observing the vertical characteristics of traffic originated particles (Tian et al., 2013). Therefore, a roadside monitoring campaign in terms of PM2.5 and PM1 concentrations and chemical components took place within the urban atmosphere of Athens (ions, OC, EC, PAHs). Being considered as traffic hot spot due to its location next to one of the busiest roads of the capital, the selected roadside allows the thorough investigation of the behavior of different, traffic-impacted, diameter particles. The placement of the experimental equipment on different heights of a 19m high building (1st and 5th floor) i) along the open road and ii) at the street canyon (H/W ratio~1.5), allocates the parallel analysis of the configured vertical and horizontal PM status. Moreover, taking into consideration the toxic and mutagenic equivalency factor (TEF and MEF, respectively) method, will be evaluated the carcinogenic and mutagenic potential of PM2.5 and PM1- bound PAHs, both horizontally and vertically. The particle mass determination was conducted according to EN 12341. The water-soluble ions and the carbon elements will be detected using suppressed ion chromatography and a carbon analyzer, respectively while the analysis of the PAHs will be performed

according to ISO 12884. During the fieldwork (8-12/9/14 & 22-26/9/14), a total of 60 samples were collected. In total, the daily PM2.5 and PM1 values did not exceed 32.4 and 27.5μg/m3, respectively. As it was expected, the obtained average load, was higher along the open road, than the one at the street canyon. In both investigated cases it should be highlighted the fact that i) the average PM2.5 peak occurred at the 1st floor while the maximum PM1 average value was recorded at the 5th one and ii) the PM1 partitioning at the PM2.5

mass was increased on the 5th floor (90% and 92% at the open road and the street canyon, respectively). It is worthy to note the significant vertical differentiation, at the street canyon, between the PM1/PM2.5 ratio on 22/9; 43% and 96% on the 1st and 5th floor, respectively.

Fig. 1 Average PM concentration on the vertical and the horizontal axis

This work was supported by thefinancial supported from the EnTeC FP7 Capacities programme (REGPOT-20122013-1, FP7, ID: 316173)

Lee, SC., Cheng, Y., Ho, K.F., Cao, J.J., Louie, PK.-K, Chow J.C. and Watson J.G. (2006) Aerosol Sci. Technol. 40, 157-165.

Rakowska, A., Wong, K.C., Townsend, T., Chan, K. L., Westerdahl, D., Ng, S., Mocnik, G., Drinovec, L. and Ning Z. (2014) Atmos Environ 98, 260-270.

Tian, Y.-Z., Shi, G.-L., Han, S.-Q., Zhang, Y.-F., Feng, Y.-C., Liu, G.-R., Gao,

L.-J., Wu, J.-H. and Zhu, T. (2013) Sci Total Environ 447, 1–9.

0

1

0

2

0

3

0 Along the

ope n

road Street Canyo n 5 th floo

r 1 st floo

r

mailto:[email protected]


31

Appendix 2:

Doped titania nano-powders with photocatalytic and antimicrobial properties under visible light irradiation

D. S. Tsoukleris1, C. Psarras1, M. Loizidou2, E. Α. Pavlatou1, G. Chousos3, P. Panagopoulos3, Ch. Vasilakos3, Th. Maggos3

1. General Chemistry Laboratory, School of Chemical Engineering, National Technical University of Athens 2 Unit of Environmental Science and Technology, School of Chemical Engineering, National Technical University of Athens

9 Heroon Polytechniou Str., Zografos Campus, Athens GR-15780, Greece 3Environmental Research Laboratory, INRASTES, NCSR “Demokritos”, Ag. Parskevi, Athens, Greece

One of the most prevalent synthetic routes for the production of doped nanostructured titania has become the so called sol-gel process, widely known as hydrolysis-condensation (SOLution-GELation) which falls into the broad class of wet chemistry methods. In this work emphasis has been given to the study of this specific synthesis route, since it has become the most frequently applied synthetic method providing various advantages.

In this study, titania nano-powder was prepared by sol–gel method using titanium butoxide (TBOT) and distilled water/ HNO3 as titanium precursor and hydrolyzing agent, respectively. An alcoholic solutions were added and the solution was stirred under vigorous stirring. Then, added the dopant urea and stirred overnight. The prepared sol-gel solution deposited onto glass spherules with spray pyrolysis method and calcinated to 450oC in order to be produced the final TiO2 thin film. X-ray diffraction patterns (XRD) of the calcinated powders were obtained with a Siemens D5000 X-ray diffractometer in the diffraction angle range 2θ = 20o-80o using Cu Kα radiation. FT-Infrared spectra were obtained on a Jasco 4200 spectrophotometer and the spectra were recorded for a wave number range from 700 to 5000 cm-1 with a resolution of 8 cm-1 by using the ATR method. Diffuse reflectance UV-Vis spectra from 200nm to 700nm with slit width of a few nm was collected on a Hitachi 3010 spectrophotometer. Moreover, morphology and particle size were studied by using electron microscopy (SEM).

In order to enhance the efficiency of TiO2 under visible irradiation, the produced nanomaterial was modified with non-metal dopants aimed to decrease the band gap that facilitates visible light absorption. In terms of the use of TiO2 in semiconductors, band gap was arguably one of the most important properties. In general, the band gap of the TiO2 nano-particles is from 3.0 to 3.2eV whereas in this study the band-gap was estimated to be below 2.5 eV by the reflectance UV-Vis spectra. The XRD data demonstrate that all powders could be characterized as nanocrystalline as well as the FEG-SEM results (Fig. 1).

The photocatalytic efficiency of the material was evaluated in a photoreactor by the photo-degradation of benzene, toluene and o-, m-, p-, xylenes and ethylbenzene (BTEX). 0.03 m2 of the powder (spherules) were placed inside a pyrex (permitting radiation pass when wavelength is over 320 nm) glass tube (50 cm in length and 1.5 cm in diameter), which in turn was incorporated in the central axis of the photoreactor. A known concentration of VOCs (approx. 20 ppb/v) with 0.2m3/h flow rate passed from the glass tube, while the 4 Vis-lamps were irradiating the system. The analysis of VOCs concentration was conducted by an automated GC-PID (955 Syntec Spectras) providing VOCs concentrations every 15 minutes interval. Preliminary results shown significant degradation of xylenes and ethyl-benzene (70% and 60% respectively) while the corresponding value for toluene was quite lower (7.44%).Accordingly the photocatalytic rate (μg/m2s) was calculated 0.03, 0.01 and 0.002 for xylene and ethyl-benzene and toluene respectively.

Figure 1. SEM image of synthesized TiO2 nano-powders


32

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