INTRODUCTION
Research rationale
Toluene is a widely used solvent in everyday life, playing a significant role in industrial applications While it serves as an essential raw material and an effective organic solvent, toluene poses serious health risks and environmental concerns.
Humans contribute significantly to toluene pollution in their environments while also being the primary victims of exposure, particularly in the manufacturing sector Despite its risks, toluene remains widely used in manufacturing due to its importance Understanding the toxicity of toluene is crucial for implementing preventive measures in its production and usage This essay focuses on toluene to highlight the benefits of minimizing Highly Toxic Organic Pollutants (HTOPs) Additionally, the photocatalytic properties of titania are explored for their effectiveness in wastewater treatment (Shen, 2016) Toluene was first discovered by P Kelley.
P Walter in 1037 when he developed coal gas from resin
This study investigates the effectiveness of photocatalysts in degrading toluene, comparing its degradation under various conditions The evolution of nanotechnology has led to innovative research applications across diverse scientific fields.
Research’s Objective
- Evaluate the capability of P25, TiO2 powder, Fe/TiO2 in the degradation of toluene
- Examine photocatalytic activity under the UVA light source
- Assess these condition has effect on the degradation of toluene
Research’s Contents
1 Literature review about toluene, its adverse effects on ecosystem and human health
2 Synthesis and investigate the characteristics of materials to the degradation of toluene
3 Compare the photocatalytic activity differences type of photocatalysts to ward toluene degradation.
Research’s Scope
The sample of toluene and photocatalyst were prepared in Environmental Nanomaterial Laboratory, Chiao Tung University, Taiwan The experimental process was done in the laboratory
LITERATURE REVIEW
Toluene
Volatile compounds like toluene significantly impact human health and the environment, leading to various side effects (Beydoun et al., 1999; Bernstein et al., 2008) Studies indicate that consistent exposure to toluene can result in neurological issues, including memory loss, impaired muscle growth, hearing loss, and color vision deficiencies (Peral et al., 1997; Neubert et al., 2001).
The Environmental Protection Agency (EPA) has detected toluene in well water, surface water, and soil, with its vapors also present in the air Due to its widespread use in consumer products, indoor air concentrations of toluene can exceed those found outdoors It is estimated that the average absorbed dose of toluene from indoor sources, combined with outdoor emissions from vehicles and gasoline, is approximately 300 µg/day.
Toluene is a crucial starting material in the explosives industry and serves as a solvent, with its concentration allowed up to 200 parts per million in air However, there is limited evidence to consistently maintain this concentration within the maximum permissible limits Air quality control is a significant concern in environmental science and technology, prompting extensive research into photocatalytic oxidation (PCO) processes PCO has proven effective in managing air quality by targeting compounds such as carbon monoxide (CO), nitrogen oxides (NO), volatile organic compounds (VOCs), and bioaerosols in enclosed environments.
TiO2 catalysts are widely recognized for their effectiveness in removing volatile organic compounds (VOCs) from polluted air due to their high activity, safety, and affordability Recent studies have clarified the process of visual oxidation of organic compounds, including aromatic compounds, when using TiO2 catalysts under close-range irradiation.
Toluene, named after the balsamic resin "toluol" from South America, is a transparent, low-viscosity liquid that is insoluble in water It readily dissolves in various organic solvents, including alcohol, ether, and ketones Due to its flammable nature, toluene is primarily utilized as an industrial feedstock and solvent.
The toluene molecule consists of two parts: the benzene ring and the ankyl ring
Toluene is an aromatic hydrocarbon characterized by the distinctive aroma of the benzene ring and the properties of its alkyl base The interaction between the benzene ring and the alkyl base modifies their characteristics Toluene primarily undergoes substitution reactions (SE) in the benzene ring and oxidation reactions at the methyl base Due to its versatile nature, toluene is extensively utilized across various industrial applications.
~ 5 ~ as a substitute for benzene: Toluene is used primarily in applications requiring solubility and the highest volatility
Toluene is a highly soluble solvent utilized in various industries, including the production of synthetic resins, automotive paints, interior paints, and marine paints It plays a crucial role in the manufacturing of adhesives and binders, serves as a diluent, and is a key ingredient in detergents Additionally, toluene is involved in the production of benzene, dyes, textiles, and numerous other applications across diverse sectors.
•If exposed to toluene for a long time, cancer may develop
• Eye contact: Stimulating, but does not affect the eye membrane
Frequent or prolonged skin contact with certain substances can lead to irritation and inflammation, while short and irregular contact typically does not cause serious irritation However, irritation is more likely to occur during evaporation, and such skin contact can result in severe dermatitis.
• Inhalation (respiratory system): High evaporation content (greater than about
1000 ppm) causes eye and respiratory irritation, can cause headaches, drowsiness, unconsciousness, affecting the nerve center , brain damage and can cause death
• Ingestion (digestive system): A small amount enters the abdomen or causes or damages the human lungs, which cause death.
TiO 2 photocatalysis
Titanium dioxide (TiO2) is a semiconductor and is famous as an anti-ultraviolet (UV) catalyst in oxidizing photos of organic matter and inactivating bacteria, algae and viruses
Titanium oxide acts as an optical semiconductor by transforming from an insulator to a conductor when it absorbs light energy This transformation occurs as excited electrons transition from the valence band to the conduction band, creating holes in the valence band The excited electrons then react with atmospheric oxygen to form superoxide anions, while the holes interact with moisture in the air to produce hydroxyl radicals These active oxygen species effectively oxidize and decompose organic matter.
Figure 2: Photo catalyst oxidation process
Titanium oxide surfaces demonstrate super permeability when the water contact angle is 5° or lower This phenomenon occurs under light irradiation, where electron-hole pairs are generated, leading to superfluidity The creation of oxygen vacancies, resulting from the interaction of holes, is a key factor in this process.
~ 7 ~ oxygen atoms in the lattice Such holes form a hydrophilic area, and because water is readily adsorbed there, super-permeable products are generally
Advanced oxidation processes (AOP) utilizing UV irradiation and titanium dioxide (TiO2) are becoming increasingly effective for wastewater treatment A thorough review highlights the various TiO2 catalysts, irradiation sources, and reactor types, comparing the efficacy of TiO2 in surface immobilization versus system suspension Photocatalytic technology with TiO2 is particularly effective for degrading organic pollutants, achieving complete mineralization under mild environmental conditions Recent studies have focused on its application in degrading persistent organic pollutants and endocrine disruptors The use of TiO2 in suspended mud reactors has gained popularity due to its simplicity and enhanced degradation efficiency, although it necessitates the separation of TiO2 from treated water The manuscript concludes with a discussion on a hybridization system employing a two-stage coagulation and microfiltration process to effectively remove TiO2, allowing for its recovery and reuse in photocatalytic applications.
Semiconductors are primary light absorbers Due to a favorable combination of electronic structure, absorption properties, they are used in photocatalysis (S Sappideen, PhD Dissertation, 2000)
(b) TiO2 was singled out as an important oxide material in the wide-ranging review of future directions in solid chemistry of nation by Cava et al (2002) for the
The photocatalytic cleavage of water on TiO2 electrodes, known as the "Honda–Fujishima Effect," was first reported by Fujishima and Honda in 1972 This process utilizes TiO2, a naturally occurring titanium oxide, to facilitate water splitting.
1795, and its commercial production started in the 1920s
Over the past few decades, a vast body of literature has explored titanium dioxide polymorphs (TiO2), highlighting its diverse properties and numerous industrial applications TiO2 is widely utilized as an opacifying agent in paints, plastics, paper, textiles, and inks, as well as in corrosion-resistant coatings, antimicrobial solutions, and air and water purification systems Additionally, it serves as a UV absorber in cosmetic products and is being researched for advanced applications in water remediation, photocatalysis, rechargeable batteries, supercapacitors, and sensor devices.
(d) Substances studied in different lighting conditions The initial reaction step involves the creation of electron-hole pairs by irradiating TiO2 with light that has
~ 9 ~ a higher energy content than the band gap (Uddin et al., 2007) For TiO2 anatase and rutile, the band gap ranges are 3.2 eV and 3.0 eV, respectively, with wavelengths of
Ultraviolet (UV) light, specifically at wavelengths of 388 nm and 410 nm, is essential for activating titanium dioxide (TiO2) photocatalysts, as it excites electron pairs in the valence band, facilitating redox reactions that decompose adsorbed organic pollutants The effectiveness of TiO2 can be enhanced by embedding it in supporting materials with large surface areas, which helps concentrate diluted pollutants and mitigates the challenges posed by small photocatalyst particles Recent years have seen various innovations in the design of TiO2 photocatalysts, incorporating auxiliary materials and different coating methods to improve the decomposition of organic compounds Notable materials used in these designs include glass beads, fiberglass, quartz, stainless steel, aluminum, activated carbon (AC), and silica, with AC being particularly effective as an adsorbent for organic pollutants in aqueous environments.
The adsorption of organic matter on activated carbon (AC) leads to a transition onto the TiO2 surface, where it is quickly attenuated This process involves the interaction of light particles with semiconductors, generating highly reactive oxygen species like hydroxyl radicals (OH•), superoxide (O2•-), and hydroperoxyl radicals (HO2•) Key factors for effective catalytic applications include the specific surface area, UV light absorption range, and the efficiency of photochemical catalysts.
Titanium dioxide (TiO2) is a simple inorganic compound that exists in four primary crystal forms: anatase, rutile, brookite, and TiO2 itself The TiO2 phase diagram reveals a variety of high-pressure phases, which geologists consider potential candidates for minerals found in the Earth's mantle Notable high-pressure polymorphs of TiO2 include columbite, baddeleyite, cotunnite, pyrite, and fluorite structures.
(g) Rutile, the most stable phase at ambient pressure and temperature at macroscopic size while anatase is more stable at nanoscale (Shannon, R.D., 1965) (h)
(o) Figure 3 Schematic image for the kinetic and thermodynamic control polymerization of TiO 6 octahedral units as the nucleation of anatase and rutile in
The geometric ratio of cis coordination positions in octahedral dimers is 7:1 for anatase compared to rutile Due to symmetry breakdown in the anatase structure, only half of the cis coordination sites are accessible This high probability of cis coordination polymerization contributes to the tendency of anatase to form metastable structures easily.
Rutile, anatase, and brookite are three forms of titanium dioxide (TiO2), each exhibiting distinct physical properties due to their structural differences Rutile features a more compact structure, resulting in a higher refractive index, greater specific gravity, and enhanced chemical stability compared to anatase While rutile melts at 1825˚C, anatase begins to irreversibly transform into rutile at approximately 500˚C Brookite, a less common natural form of TiO2, shares similar color and luster with rutile, and its hardness and density closely resemble those of rutile Although TiO2 is not as widely recognized as its counterparts, it was first synthesized in 1980 and later discovered in nature in 1991.
TiO2(B), named for its resemblance to tungsten bronze compounds, is the least dense polymorph of titanium dioxide, making it an excellent host for lithium ions compared to other forms Despite its potential, the metastable nature of TiO2(B) has limited research in electrochemistry.
The primary challenge in utilizing TiO2 as a photo-activated catalyst is its significant energy gap between the conduction and valence bands, which limits electron excitation to only 3%–4% of the air-mass 1.0 solar spectrum To enhance its effectiveness with visible light, extensive efforts have been directed towards reducing the TiO2 band gap This reduction not only aims to improve its catalytic performance but also holds promise for advancing renewable energy applications, such as photovoltaic cells and hydrogen production through photocatalysis.
The thermodynamic properties of micro- and nanoparticles are significantly influenced by surface energy, which plays a crucial role in determining their characteristics Due to their smaller size, nanoparticles possess larger surface areas, resulting in increased surface energy.
To maximize the efficiency of photocatalytic reactions, depositing noble metals on semiconductor nanoparticles is crucial, as these metals serve as sinks for photo-induced charge carriers, enhancing interfacial charge transfer The lower Fermi concentration of noble metals compared to TiO2 allows photo-excited electrons to migrate from the conduction band to the metal particles, while holes remain in TiO2, significantly reducing electron-hole recombination and promoting stronger photocatalytic reactions Doping TiO2 alters its surface properties, including the thickness of the space charge layer and the concentration of surface states, thereby modifying its chemical nature and electronic structure Narrowing the band gap of TiO2 enhances its photoactivity in the visible spectrum, with changes in the threshold energy for doped Titania samples leading to a red shift in the adsorbed edge, improving luminescent properties The overall photocatalytic activity is influenced by alterations in the bulk electronic structure of the semiconductor, affecting electron-hole generation and separation under illumination, while factors such as the Fermi energy level and the formation of new energy levels impact surface properties and the potential for photocorrosion.
Research indicates that oxygen vacancies and associated color centers in doped TiO2 are the primary factors contributing to the observed red-shift of the absorption edge, enhancing light sensitivity.
Photocatalysis
Photocatalysis involves the absorption of light photons by a catalyst, which excites electrons from the valence band to the conduction band, creating electron-hole pairs These pairs serve as redox centers that effectively trigger oxidation-reduction reactions on the catalyst's surface, leading to the degradation of harmful pollutants (S Swetha et al, 2011).
Transition-metal ions play a crucial role in photocatalytic reactions by influencing reaction rates and facilitating the conversion of harmful ions into less toxic forms or enabling the recovery of valuable metals from semiconductor catalysts Titanium dioxide (TiO2) is widely used in photocatalysis for various applications, including water dissociation, air and water purification, removal of indoor odors, antibacterial treatments, and self-cleaning surfaces Additionally, TiO2 exhibits photo-induced superhydrophilicity, which enhances its effectiveness The photocatalytic activity of titanium oxide is primarily determined by the surface charge carrier transfer rate and the recombination rate of electrons and holes Furthermore, particle size significantly impacts the catalyst's surface activity; smaller particles increase the specific surface area and active sites, although there is an optimal size for maximum efficiency.
Particles with a size of approximately 10 nm exhibit the highest surface activity, as noted by Zhang et al (1998) However, when particle sizes fall below 10 nm, the surface recombination rate tends to increase, leading to a decrease in catalytic activity Therefore, achieving an optimal balance between particle size, surface activity, and recombination centers is crucial for developing the most efficient photocatalysts.
UV absorption
Inorganic sunscreen filters are essential for blocking UV light across the entire UV-A and UV-B spectrum (290–400 nm) through their absorption, scattering, and reflection properties These properties are influenced by factors such as the refractive index, particle size, emulsion dispersion, and film thickness Effective sunscreens should also be photostable, ideally achieving 100% stability, while efficiently scattering absorbed energy to prevent the formation of harmful reactive oxygen species Titanium dioxide (TiO2) is particularly effective in blocking UV-B rays and provides reasonable protection against UV-A radiation, ensuring good transmission in the range above 400 nm.
TiO2 nanoparticles, with sizes reduced to 10–20 nm, achieve an optimal balance of scattering and absorption at 700 nm, ensuring excellent protection while maintaining satisfactory transparency When activated by UV light, these nanoparticles generate highly oxidizing radicals, including hydroxyl (OH) and superoxide (O2-), as well as other reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) and singlet oxygen (O2), which are recognized for their cytotoxic and genotoxic effects.
MATERIALS AND METHODOLOGY
Materials
Powdered TiO2; Fe-TiO2 were formed in laboratory and selected in this study P25 is a commercial product that supplied by Environmental Nanomaterial Lab, Chiaotung universisy, Taiwan
LED UVA is provided by Environmental Nanomaterial Lab.
Experimental methods
3.2.1 Synthesis TiO 2 and Fe-TiO 2
Step1: Pour 30ml of IPA into the tube then pour 4ml of TTIP onto the surface of the tube
Step 2: Place the tube on the contrifuge for 2 minutes at 200rpm
Step 3: After contrifugation, pour compound into the dish to dry in 2 hours at 95C-100C After the first one hour grind the compounds to let isopropennal vapour
Step 4: Grind the powder into the oven for 3 hours at 300 degrees Celsius
Prepare TiO2 powder as the initial step In this experiment need:
The molar ratio of Ferric Nitrate, 9-Hydrate to IPA is 1:5
Step 1: Apply IPA solution to the tube containing TiO2 powder Pump 0.5ml of
Fe +3 solution into the tube Use an ultrasonic machine to separate the residue and solution within 10 minutes
Step 2: Continue the tube on the contrifuge machine to allow the sediment to settle at 10000rpm for 3 minutes
Step 3: Put the dregs into the furnace at a temperature of 500 degrees Celsius for 3 hours
3.2.2 Test the degradation rate of toluene by using 3 samples of powder produced
Prepare three petri dishes glass, each dish containing 0.3gram of powder
In a degradation test, the powder was placed in a reactor with an equal amount of toluene and exposed to LED UVA energy The absence of water in the reactor resulted in the fastest degradation of toluene, followed by indoor gas Conversely, when using humidified air at 100% humidity, the photocatalyst's surface became saturated with water, causing the toluene absorption process to take significantly longer compared to the drier environments.
This experiment was conducted at room temperature
3.2.4 Investigate the effective way to let the degradation process go faster
Experiments were conducted to investigate the kinetics of toluene adsorption on selected Fe-TiO2 powder using filter paper The photocatalyst was synthesized with varying amounts of chemicals, resulting in different products.
By applying the same step as doping Fe into TiO2 but to get the most Fe-TiO2 powder, filter paper was used
After doping Fe, the solution was poured onto the filter paper during using gravitational filtration Then put the finished product into the furnace overnight at
To examine the conditions affect the degradation process some factors is not change as:
Figure 4: Photocatalyst was irradiated using UVA LED 370nm
RESULTS
Result of synthesis photocatalyst
The photocatalyst was synthesis in different amount of chemicals make different products
The powder has the milk white colour and smooth
Figure 6: TiO 2 powder made in laboratory
This product is pure white and has a little sparkle
4.1.3 Product of doped iron(Fe)
Figure 7: Fe-TiO2 powder made in laboratory The powder was consumed has a little red colour from Fe doped.
Results of photocatalyst by deposition
Figure 8: Product of iron doping on TiO 2 using filter paper
By using filter paper, TiO2 doped Fe was synthesis with the best quality of powder
Results of different conditions
To test the degradation of toluene, the light source has no change in three environmental conditions
Figure 9: Environment condition affect to the degradation of toluene
The degradation of toluene occurred most rapidly in a dry reactor, followed by the degradation in indoor gas In contrast, humidified air at 100% humidity caused the photocatalyst surface to retain more water, resulting in a prolonged toluene absorption time compared to the drier environments Throughout the experiment, the light source remained constant across all three environmental conditions.
Dried Air Humidified Air Indoor Gas
Results of different light intensity
To investigate the impact of light intensity on degradation, UVA LED was positioned at two distances: 1.5 cm and 2.5 cm from the photocatalyst surface, with consistent temperature and humidity throughout the experiment.
Figure 10: Light irradiation at different distance to the photocatalyst
At a closer distance, the intensity of light significantly enhances the effectiveness of the photocatalyst, leading to a more rapid reduction of toluene concentration within the reactor compared to light at a greater distance Additionally, sorption equilibrium is achieved after 30 minutes of exposure.
Results of different concentration
To evaluate the impact of concentration on toluene degradation, experiments were conducted at a light intensity set at the initial distance, with environmental conditions maintained at 25-ppm, 50-ppm, 100-ppm, and 200-ppm The humidity was consistent at 17%, and the room temperature was held at 23°C.
Figure 11: Different concentration degradation through the time
As the concentration of toluene in the reactor decreased, the time required for its degradation also reduced Figure 11 illustrates that the removal efficiency of toluene diminished with increasing concentrations.
The photocatalyst demonstrated effective toluene degradation efficiency at concentrations of 25ppm and 50ppm within one hour As the concentration of toluene increased, the degradation efficiency also improved; however, higher concentrations required more time for complete degradation.
Discussion and Conclusion
Discussion
Titanium dioxide (TiO2) is a wide band-gap semiconductor with its primary polymorphs—rutile, anatase, and brookite—exhibiting band-gaps between 3.05 and 3.18 eV The functional performance of TiO2 is largely influenced by its band structure, which is affected by variations in crystal structure and the stoichiometry or chemical identity of its constituent atoms.
Yamashita et al also studied the visible light activity of transition metal implanted TiO2 using XAFS analysis and theoretical calculations The substitution of
Ti ions by isolated metal ions is the determining factor for the utilization of solar light Yamashita et al also studied the properties of Fe ion-implanted TiO2
The study investigated the photochemical degradation of toluene under UV irradiation, both with and without the presence of TiO2 Results indicate that without TiO2, the photo catalytic decomposition of toluene was minimal However, the introduction of TiO2 into the reactor significantly enhanced the degradation rate of toluene.
Light intensity effected: The UVA intensity has effect of on the photocatalytic efficiency of prepared catalysts was investigated by changing the position of UV source lamps
Under UV irradiation, a photo reactor effectively decomposed toluene in the gas phase through a photocatalytic reaction Previous studies have examined the interaction effects of using TiO2 in the photocatalytic degradation of toluene.
For the decomposition of toluene, the rate of decomposition is almost independent of the initial toluene concentration This suggests that the catalyst coating
The increased speed of UVA light transmission enhances the interaction between the catalyst's surface and toluene, leading to more efficient decomposition over shorter time periods However, at higher toluene concentrations, the decomposition rate declines due to the formation of intermediate products, which affects the overall process.
Experimental results indicate that toluene decomposition increases with higher UV light intensity, with a greater photo catalytic efficiency observed at a 1.5 cm distance from the lamp compared to 2.5 cm Increased UV intensity generates more photons, which enhances the photo catalytic reaction and leads to the formation of more hydroxyl radicals (OH•) that effectively decompose toluene Consequently, as UV light intensity rises, the rate of toluene decomposition also increases Various photo catalytic oxidation methods have been proposed in the literature (Carp et al., 2004; Zhang et al., 2007; Saquib et al., 2008).
Surface oxidation involves the transfer of photosynthetic electrons to adsorbed holes, facilitating interactions between ionic surface species, as noted by Amalric et al (1994) It is widely recognized that the complete degradation of organic molecules is enhanced by surface mechanisms where these molecules react in the adsorbed phase (Aramendía et al., 2008) Additionally, alternative oxidation pathways may necessitate the attack of hydroxyl (OH) radicals, which can be generated through water splitting or O2 - intermediates, as suggested by various authors (Saquib et al., 2008).
The TiO2 sample exhibits a high concentration of conduction electrons, which may enhance the surface reduction of O2 to O2- without the need for photogeneration This process could be influenced by competition between O2 adsorption and other molecules, alongside the potential dissociation of water Additionally, homogeneous pathways involving OH radical attacks may occur The laboratory-prepared nano TiO2 catalyst demonstrated strong photocatalytic performance, with the degradation rate of toluene significantly affected by operating parameters such as initial toluene concentration and ultraviolet light intensity Notably, the degradation rate of toluene increased with higher UVA light intensity.
Conclusion
In this study, three materials were characterized and used for degradation of toluene The following conclusions were based on the results obtained from the experiment:
•Dopping ferric on TiO2 is better on degradated toluene because it preserves a higher degree of charge carriers and promotes charge utilization
• Although the deposition is lighter than the coating, the effect is better Deposition can make the surface of photocatalyst uniform, that make the degradation go faster by irradiation
•The time for toluene concentration to reach equilibrium state was around 20 minutes to 30 minutes
• Light source at different distance has effect to the degradation The samples were irradiation with more light intensity make the degradation process become faster
Environmental conditions significantly influence the degradation of toluene, with dry environments enhancing the activity of photocatalysts in absorbing toluene compared to humid conditions.
Agrios, A.G.; Pichat, P State of the art and perspectives on materials and applications of photocatalysis over TiO2 J Appl Electrochem (2005), 35,
Ao, C H., Lee, S., (2003) Enhancement effect of TiO2 immobilized on activated carbon filter for the photodegradation of pollutants at typical indoor air level, Appl Catal., 44: 191–205
Aramendía, M A., Borau, V., Colmenares, J C., Marinas, A., Marinas, J M.,
Navío, J A., Urbano, F J., (2008) Modification of the photocatalytic activity of Pd/TiO2 and Zn/TiO2 systems through different oxidative and reductive calcination treatments Appl Catal B: Environ., 80: 88-97
B Ohtani, Preparing Articles on Photocatalysis―Beyond The Illusions,
Misconceptions and Speculation, Chem Lett., 37 (2008)
Banerjee, A.N., The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures
Beydoun, D., Amal, R., Low, G., (1999) Role of nanoparticles in photocatalysis J
Carp, O., Huisman, C L., Reller, A., (2004) Photoinduced reactivity of titanium dioxide Prog Solid State Ch., 32: 33-177
Caruso, G., Merlo, L., & Caffo, M (2014) Nanoparticles potential: types, mechanisms of action, actual in vitro and animal studies, recent patents
Chang, X., Y Zhang, M Tang, and B Wang, Health effects of exposure to nano- TiO2: a metaanalysis of experimental studies Nanoscale research letters, 2013 8(1): p 1-10
Chen, X.; Mao, S.S Titanium dioxide nanomaterials: Synthesis, properties, modifications, and applications Chem Rev (2007), 107, 2891–2959
Contado, C and A Pagnoni, TiO2 in commercial sunscreen lotion: flow field-flow fractionation and ICP-AES together for size analysis Analytical chemistry, 2008 80(19): p 7594-7608 164
Fujishima A, Rao T.N, Tryk D.A.(2000) Titanium dioxide photocatalysis J
Fujishima, A.; Honda, K Electrochemical Photolysis of Water at a Semiconductor Electrode Nature 1972, 238, 37–38
Higashimoto, S.,Tanihata, W., Nakagawa, Y., Azuma, M., Ohue, H., Sakata, Y.,
(2007) Effective photocatalytic decomposition of VOC under visible- light irradiation on N-doped TiO2 moddified by vanadium species Appl
Hoffman, M.R.; Martin, S.T.; Choi, W.Y.; Bahnemann, D.W Environmental applications of semiconductor photocatalysis.(2000) Chem Rev 1995,
Juliano , R.L.( 1978 ) Drug delivery systems: a brief review Can J Physiol
Korean J Chem Eng.,(2008), A review on UV/TiO 2 photocatalytic oxidation process, 64-72
Lazzeri, M., A Vittadini, and A Selloni, Structure and energetics of stoichiometric TiO 2 anatase surfaces Physical Review B, 2001 63(15): p 155409
Linsebigler, A.L.; Lu, G.; Yates, J.T., Jr Photocatalysis on TiO 2 surfaces:
Principles, mechanisms, and selected results.(1987) Chem Rev 1995,
Matsudai , M , and Hunt , G.( 2005 ) Nanotechnology and public health Nippon Koshu Eisei Zasshi, 52 : 923 – 7
N.A Mir, M.M Haque, A Khan, K Umar, M Muneer, S Vijayalakshmi, J Adv Oxid Technol 15 (2012) 380–391
Ollis, D.F Photocatalytic purification and remediation of contaminated air and water C R Acad Sci Ser (2000), 3, 405–411
Peral, J., Domenech, S., Ollis, D F., (1997) Heterogeneous photocatalysis for purification, decontamination and deodorization of air J Chem
Rahimi N, Pax RA, Gray EM Review of functional titanium oxides I: TiO 2 and its modifications, Progress in Solid State Chemistry (2016)
Saquib, M., Tariq, A., Faisal, B., Muneer, M., (2008) Photocatalytic degradation of two selected dye derivatives in aqueous suspensions of titanium dioxide
Shannon, R.D and J.A Pask, Kinetics of the Anatase-Rutile Transformation Journal of the American Ceramic Society, 1965 48(8): p 391-398
Shen, X (2016) Molecularly Imprinted Photocatalysts Molecularly Imprinted