Photocatalytic Degradation Of Acetone Research Articles

Mo3S13]2− modified TiO2 coating on non-woven fabric for efficient photocatalytic mineralization of acetone

Improving the photocatalytic efficiency of commercial TiO2 has important significance for practical application of TiO2 based photocatalysts. A novel photocatalyst [Mo3S13]2−/TiO2 was fabricated by combining [Mo3S13]2− with commercial TiO2 by an impregnation method. This composite photocatalyst presented a remarkable enhancement on photocatalytic mineralization of acetone in comparison with commercial TiO2. The optimum loading amount of [Mo3S13]2− was 1.7wt%, which is more efficient than the Pt/TiO2 (1.5wt%). Electrochemical impedance spectroscopy (EIS) showed the smooth electron transfer pathway in [Mo3S13]2−/TiO2 composite, facilitating the photo-charges separation during the photocatalysis process. Reactive oxygen species scavenging test illustrated that superoxide radical (O2−), hydroxyl radical (OH) and photo-induced hole (h+) were all contributing to the acetone degradation. The [Mo3S13]2−/TiO2 photocatalyst was deposited on non-woven fabrics which showed obvious promotion on the photocatalytic degradation of acetone in comparison with pristine commercial TiO2.

Comparing the photocatalytic activity of TiO2 at macro- and microscopic scales

This study focuses on the characterization of photocatalytic TiO2 coatings using Kelvin probe force microscopy. While most photocatalytic experiments are carried out at a macroscopic scale, Kelvin probe force microscopy is a microscopic technique that is surface sensitive. In order to link microscale results to macroscopic experiments, a simple method to establish the relation between Kelvin probe force microscopy and electrochemical measurements is presented by the calibration of a reference sample consisting of epitaxial deposited Cu-Ni-Au that is used as a transfer standard. The photocatalytic properties of TiO2 at macro- and microscopic scales are investigated by comparing photocatalytic degradation of acetone and electrochemical experiments to Kelvin probe force microscopy. The good agreement between the macro- and microscopic experiments suggests that Kelvin probe force microscopy can be a valuable tool towards the understanding, standardization and design of TiO2-based solutions in photocatalytic applications.

Photocatalytic degradation of acetone and methanol in a flow-through photoreactor with immobilized TiO2

Volatile organic compounds must be used in many industrial processes, involving their emission to the environment in gaseous form. This paper describes the degradation of vapors of acetone and methanol in air by photocatalysis. To achieve this, a tubular flow-through reactor with TiO2 photocatalyst irradiated by either UV-A or UV-C lamps is used. The irradiation wavelength was the main studied parameter. Equal volumetric feed of liquid in the air stream for both pollutants resulted in a concentration of acetone of about 275 ppm and of methanol of about 500 ppm. In separate experiments, using the UV-A lamps, the conversion of acetone was 29 %, while for methanol it was 72 %. The faster oxidation of methanol relative to acetone can be explained by their different molecular structure. For UV-C lamps, the conversion of acetone significantly increased (to 60 %), while that of methanol increased only slightly (to 80 %). The contribution of photolysis to the degradation of both compounds was considered and finally evaluated to be negligible in this setup.

Photocatalytic degradation of acetone, acetaldehyde and toluene in gas-phase: Comparison between nano and micro-sized TiO2

Volatile organic compounds (VOCs) are prevalent components of indoor air pollution. The photocatalytic degradation could be an interesting method to degrade them.This paper reports the photoactivity study of two classical nano-sized and two micro-sized commercial TiO2 powdered samples. Photocatalytic tests have been performed following the degradation of acetone, acetaldehyde and toluene in the gas phase under UV light. An accurate study of the intermediate oxidation products was performed. XPS and FTIR analyses allowed to highlight the relationship between TiO2 surface properties and reactivity toward VOCs explaining the different behavior of the photocatalyst in case of hydrophilic and hydrophobic pollutants.

Photocatalytic Activity of Titanium Oxide – Iron Oxide Coatings Prepared by Plasma Spraying

This study examines the photocatalytic activity of coatings produced by atmospheric plasma spraying (APS). The spraying tool used is a water -stabilized plasma gun WSP. The TiO2 �Fe2O 3powder withand withoutNa 2SiO3additive was agglomerated to build p articles suitable for feeding into the plasma jet and spraying. The coatings are analyzed by scanning electron microscopy, X -ray fluorescence and Xray diffraction. Photocatalytic degradation of acetone as well as the growth kinetics of the products -carbon dioxide and carbon monoxide -is quantified for both coating types and compared with a pure TiO 2 coating. The coatings show a lamellar structure, as is typical for this technological process. Howe ver the porosity is rather high. Anatase titania from the feedstock powder is converted to rutile phase whereas a presence of FeTiO 3is detected in the coating without Na 2SiO3. The coating from powder withNa 2SiO3 admixture is amorphous. Both coatings aremore photocatalytically active than the reference TiO 2coating.

Photocatalytic degradation of acetone and butane on mesoporous titania layers

Mesoporous titania was prepared by homogeneous hydrolysis of titanium oxo-sulfate with urea in aqueous solutions in the presence of the cationic and anionic surfactants, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl benzene sulfonate (SDBS), respectively. Following annealing at 600 °C the structure of prepared samples was determined with X-ray powder diffraction (XRD) and selected area electron diffraction (SAED). The morphology and microstructure characteristics were also obtained by scanning electron microscopy (SEM) and high resolution electron microscopy (HRTEM). Surface area (BET) and porosity were also determined. From the mesoporous titania samples, a 300 μm thin layer on glass desk 10 × 15 cm was created. The photocatalytic activity of the prepared layers was assessed from the kinetics of the photocatalytic degradation of butane and acetone in the gas phase.

Effects of microwave drying on the microstructure and photocatalytic activity of bimodal mesoporous TiO 2 powders

Bimodal nanocrystalline mesoporous TiO 2 powders with highly photocatalytic activity were prepared by a hydrothermal method using tetrabutylorthotitanate as precursor, and then dried in microwave oven. The prepared samples were characterized by XRD, SEM, TEM, HRTEM and N 2 adsorption–desorption measurement. The photocatalytic activity was evaluated by the photocatalytic degradation of acetone in air under UV light irradiation at room temperature. The effects of microwave drying on the microstructures and photocatalytic activity of the TiO 2 powders were investigated and discussed. The results show that microwave drying not only promotes the growth of the pores but also greatly reduces the state of agglomeration within the powders. All the microwave-dried TiO 2 powders show higher photocatalytic activity than Degussa P-25 (P25) and the TiO 2 powders dried by conventional method.

Atmospheric plasma sprayed (APS) coatings of Al2O3–TiO2 system for photocatalytic application

The goal of this study is to examine the photocatalytic ability of coatings produced by atmospheric plasma spraying (APS). The plasma gun used is a common gas-stabilized plasma gun (GSP) working with a d.c. current and a mixture of argon and hydrogen as plasma-forming gas. The TiO(2) powders are particles of about 100 nm which were agglomerated to a mean size of about 55 mum, suitable for spraying. Composition of the commercial powder is 13 wt% of TiO(2) in Al(2)O(3), whereas also in-house prepared powder with the same nominal composition but with agglomerated TiO(2) and conventional fused and crushed Al(2)O(3) was sprayed. The feedstock materials used for this purpose are alpha-alumina and anatase titanium dioxide. The coatings are analyzed by scanning electron microscopy (SEM), energy dispersion probe (EDS) and X-ray diffraction. Photocatalytic degradation of acetone is quantified for various coatings. All plasma sprayed coatings show a lamellar structure on cross section, as typical for this process. Anatase titania from feedstock powder is converted into rutile titania and alpha-alumina partly to gamma-alumina. Coatings are proven to catalyse the acetone decomposition when irradiated by UV rays.

Photochemistry of the Indoor Air Pollutant Acetone on Degussa P25 TiO2 Studied by Chemical Ionization Mass Spectrometry

We have used chemical ionization mass spectrometry (CIMS) to study the adsorption and photochemistry of several oxygenated organic species adsorbed to Degussa P25 TiO2, an inexpensive catalyst that can be used to mineralize volatile organic compounds. The molecules examined in this work include the common indoor air pollutant acetone and several of its homologs and possible oxidation and condensation products that may be formed during the adsorption and/or photocatalytic degradation of acetone on titanium dioxide catalysts. We report nonreactive uptake coefficients for acetone, formic acid, acetic acid, mesityl oxide, and diacetone alcohol, and results from photochemical studies that quantify, on a per-molecule basis, the room-temperature photocatalytic conversion of the species under investigation to CO2 and related oxidation products. The data presented here imply that catalytic surfaces that enhance formate and acetate production from acetone precursors will facilitate the photocatalytic remediation of acetone in indoor environments, even at room temperature.

Hydrothermal synthesis and photocatalytic activity of nanocrystalline TiO 2 powders in ethanol–water mixed solutions

Bimodal mesoporous nanocrystalline TiO 2 powders were synthesized by a hydrothermal method using tetrabutylorthotitanate as precursor in ethanol–water mixed solutions. The as-prepared TiO 2 powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and N 2 adsorption–desorption measurements. The photocatalytic activity of the as-prepared TiO 2 powders was evaluated by the photocatalytic degradation of acetone under UV-light irradiation at room temperature in air. The effects of alcohol content on the microstructures and photocatalytic activity of the TiO 2 powders were investigated and discussed. The molar ratios of EtOH to H 2O obviously influenced the crystallization, crystallite size, BET specific surface areas and photocatalytic activity of the prepared TiO 2 powders. Hydrothermal treatment enhanced the phase transformation of the TiO 2 powders from amorphous to anatase and crystallization. It was found that the photocatalytic activity of TiO 2 powders prepared at 150–200 °C for 3–24 h in an ethanol–water mixed solution greatly exceeded that of Degussa P25. All TiO 2 powders after hydrothermal treatment showed bimodal pore-size distributions in the mesoporous region: one was intra-aggregated pores with maximum pore diameters of ca. 2–8 nm and the other inter-aggregated ones with maximum pore diameters of ca. 41–48 nm.

Effects of hydrothermal temperature and time on the photocatalytic activity and microstructures of bimodal mesoporous TiO2 powders

Bimodal nanocrystalline mesoporous TiO2 powders with high photocatalytic activity were prepared by a hydrothermal method using tetrabutylorthotitanate (TiO(C4H9)4, TBOT) as precursor. The as-prepared TiO2 powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption measurements. The photocatalytic activity of the as-prepared TiO2 powders was evaluated by the photocatalytic degradation of acetone (CH3COCH3) under UV-light irradiation at room temperature in air. The effects of hydrothermal temperature and time on the microstructures and photocatalytic activity of the TiO2 powders were investigated and discussed. It was found that hydrothermal treatment enhanced the phase transformation of the TiO2 powders from amorphous to anatase and crystallization of anatase. All TiO2 powders after hydrothermal treatment showed bimodal pore-size distributions in the mesoporous region: one was intra-aggregated pores with maximum pore diameters of ca. 4–8nm and the other with inter-aggregated pores with maximum pore diameters of ca. 45–50nm. With increasing hydrothermal temperature and time, the average crystallite size and average pore size increased, in contrast, the Brunauer-Emmett-Teller (BET) specific surface areas, pore volumes and porosity steadily decreased. An optimal hydrothermal condition (180°C for 10h) was determined. The photocatalytic activity of the prepared TiO2 powders under optimal hydrothermal conditions was more than three times higher than that of Degussa P25.

Photocatalytic degradation of acetone by Ni-doped titania thin films prepared by dc reactive sputtering

Two series of titania-based photocatalysts were prepared by the sputtering method, in Ar/H2O atmosphere, utilizing a Ti target modified with 1–6 Ni inserts. The first catalysts series (samples 1–5) was deposited under the total pressure of 6×10−3mbar (16% water vapor), while for the second series (catalysts 6–9) the total pressure was 3×10−3mbar (33% H2O). XRD data showed that Ni could accommodate to the titania matrix only within certain concentration limits. Ni presence in the catalysts composition does not influence significantly the morphology or the electric properties of the films, but exhibits a strong influence over the photocatalytic properties. The highest conversion in the photocatalytic decomposition of acetone was obtained in the first catalysts series for sample 2 (0.41 Niat.%, conversion rate 47%), while in the second series, the most active catalyst was sample 7 (0.13 Niat.%, conversion rate 25%). Reusing sample 3 for several runs leaded to an improvement in its catalytic behavior. The photocatalytic activity was found to be strongly influenced by the amount of Ni and the deposition conditions.

A Comparative Study on Preparation of TiO<sub>2</sub> Pellets as Photocatalysts Based on Different Precursors

The porous TiO2 pellets were prepared based on pigment grade titaina, P25 titania powder and titanium(IV) butoxide. The characterization was done with X-Ray diffraction, scanning electron microscopy and BET measurements. The result shows that TiO2 pellets by using titanium(IV) butoxide with some addictive have the best surface porosity, with specific surface area of 196.9m2/g. For pigment grade titania and P25 titania powder, it is still effective to enhance the surface area after reassembling. The surface area increased from 11.6 to 29.2 m2/g for pigment grade titania and from 50 to 84.4 m2/g for P25 titania powder. Furthermore, it has been investigated on how to optimize and get the highest surface area by controlling the sintering temperature, reaction temperature, pH of solution, and the amount of alcohol and addictive of surfactant during preparation. The experimental photocatalytic degradation of acetone and toluene was performed using titania pellets made from P25 titania powder.

Effects of calcination temperature on the photocatalytic activity and photo-induced super-hydrophilicity of mesoporous TiO2 thin films

Mesoporous TiO2 nanometer thin films were prepared on fused quartz by the dip-coating sol–gel method from a system containing a triblock copolymer as a template (or pore-forming agent), and then calcined at different temperatures. These films were characterized by X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, BET surface area and UV-visible spectrophotometry. The photocatalytic activity and photo-induced super-hydrophilicity of the films were evaluated by the photocatalytic degradation of acetone and water contact angle measurement in air, respectively. It was found that the thin films calcined at 700 °C not only show the highest photocatalytic activity, but also possess the greatest light-induced hydrophilicity and the slowest conversion rate from the hydrophilic to a hydrophobic state. The former is attributed to the fact that the films calcined at 700 °C are composed of anatase and rutile, which is beneficial in enhancing the transfer of photo-generated electrons from the anatase to the rutile phase, reducing the electron–hole combination rate in anatase and enhancing its activity. The high light-induced hydrophilicity and slow hydrophilic to hydrophobic conversion rate are due to the synergetic effect of good photocatalytic activity, sufficient surface hydroxyl content and a degree of surface roughness. Because of their high specific surface areas and mesoporous structures, the photocatalytic activity of mesoporous TiO2 thin films is higher than that of conventional TiO2 thin films.