Degradation Of Acetone Research Articles

Nanocomposite of Ag–AgBr–TiO2 as a photoactive and durable catalyst for degradation of volatile organic compounds in the gas phase

The nanocomposites of Ag–AgBr–TiO2 photocatalyst have been prepared by a simple deposition–precipitation method, which is used for the gas-phase degradation of volatile organic pollutants of aromatic benzene and non-aromatic acetone that are notorious volatile organic compounds (VOCs) present in indoor and outdoor air. A collection of joint techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet/visible diffuse reflectance spectra (UV/vis DRS) have been employed to determine the structure, morphology and optical properties of the as-prepared Ag–AgBr–TiO2 nanocomposite. The presence of surface Ag species existed as Ag (0) and Ag (I) in Ag–AgBr–TiO2 is confirmed by the analysis of X-ray photoelectron spectroscopy (XPS). The Fourier transformed infrared spectroscopy (FT-IR) analysis shows the enhanced chemical bonding of O–Ti and O–Ti–O after the deposition of AgBr and Ag species onto the surface of TiO2. It is found that the Ag–AgBr–TiO2 nanocomposite exhibits much higher photocatalytic activity and stability under both UV light and visible light irradiation as compared with that over commercial titania (Degussa P25) toward the gas-phase degradation of both aromatic benzene and non-aromatic acetone. The active radical species involved for degradation reactions over the Ag–AgBr–TiO2 photocatalyst have been investigated by the spin-trapping electron paramagnetic resonance (EPR) spectra and the OH-trapping photoluminescence (PL) spectra. Synergetic effects between Ag–AgBr and TiO2 have been observed and discussed for the gas-phase degradation of volatile organic compounds on the basis of joint results of characterization and photocatalytic activity.

Photocatalytic Degradation of Acetone over Sulfated MoOx/MgF2 Composite: Effect of Molybdenum Concentration and Calcination Temperature

This paper presents a novel visible-light-driven catalyst, a SO42–/MoOx/MgF2 composite, which was synthesized by a simple solution method. Multiple techniques, including Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS) were applied to investigate the physical and photophysical properties of the catalysts. The photocatalytic activities were evaluated in the degradation of acetone in gas phase. In the photodegradation of acetone, the highest conversion was obtained over a catalyst containing 5 mol % molybdenum. The XRD and Raman characterizations indicate that the molybdenum oxide was highly dispersed in the MgF2 matrix. These MoOx species might be the active sites of the catalysts, which is the reason for the visible-light response of the composite catalyst. The MgF2 matrix acts to isolate the MoOx species and retard the electron–hole pair recombination. When the molybdenum concentration is >5 mol %, crystalline MoO3 phase was observed. The large MoO3 particle would decrease the separation efficiency. Thus, the photocatalytic activity was reduced. Besides the molybdenum concentration, the calcination temperature also shows a great effect on the activity. A sulfated 5 mol % MoOx/MgF2 catalyst that was calcined at 350 °C showed the highest photocatalytic activity. Based on the results of the characaterization, the origin of the high activity was discussed. The light absorption ability and the MoOx size effect are considered as the key factors.

Synthesis, characterization and photocatalytic performance of VDyO x composite under visible light irradiation

A VDyO x (V 2O 5/DyVO 4) composite photocatalyst was prepared using a simple solution method. The powders were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) method, Raman spectroscopy (Raman), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Visible light-induced photocatalytic activities of the powders were evaluated by the degradation of acetone. Results generally show that the binary semiconductors V 2O 5/DyVO 4 with matching band potentials exhibit better photocatalytic properties compared with those of the single phase V 2O 5 or DyVO 4. An acetone conversion of 91.6% was achieved over V 1.5Dy 1O x composite photocatalyst under visible light irradiation. Effective electron–hole separation in the two semiconductors is believed to be mainly responsible for the increased photocatalytic performance of composites. The performance of the VDyO x composite catalyst can be further improved by loading a small amount of Pt. In addition, the Pt doped V 1.5Dy 1O x catalyst was also proven to be efficient in the photodegradation of 2-propanol and benzene.

Preparation, characterization and activity evaluation of V 2O 5–LaVO 4 composites under visible light irradiation

This article presents a novel visible-light-driven catalyst, an LaVO x composite that was prepared from La(NO 3) 3 and NH 4VO 3 solutions. The visible-light-induced photocatalytic activity of this composite was evaluated by the degradation of acetone. Results indicate that the LaVO x composite exhibits high activity for acetone photodegradation. The highest acetone conversion (93.1%) was obtained with the La 1V 1.5O x catalyst. Its photo-activity and ability for complete oxidation could be enhanced further by doping with a small amount of the metal platinum. Physical and photophysical properties of the LaVO x composite catalysts were evaluated by X-ray diffraction (XRD), the Brunauer–Emmett–Teller (BET) method, Raman spectroscopy (Raman), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Based on the results of this investigation, the coupling effect of m-LaVO 4 and V 2O 5 was identified as generating the high activity in catalysis.

LC-MS Analysis of Low Molecular Weight Carbonyl Compounds as 2,4-Dinitrophenylhydrazones Using Negative Ion Mode Electronspray Ionization Mass Spectrometry

Organic compounds in the environment, such as pesticides, degrade into inorganics via transformation into carbonyl compounds, such as formaldehyde, acetaldehyde, and acetone. 2, 4-Dinitrophenylhydrazones of 37 carbonyl compounds were prepared with 2, 4-dinitrophenyl hydrazine (DNPH). Their ESI negative spectra and EI positive spectra were obtained using an HPLC-mass spectrograph. EI positive spectra showed more ions than ESI negative spectra except in the case of two hydrazones. Molecular ions (M+) of carbonyl-DNPHs appeared as a base peak in the EI positive spectra in the case of all but 8 hydrazones. Many significant ions for the identification of a specific carbonyl compound are obtained by ESI negative spectra. Analysis of acetone in various waste waters was successfully conducted using a newly developed ESI negative spectroscopy method-levels found in the samples ranged from 2.1 mg/L to135.0 mg/L. Results of similar tests of the rate of acetone degradation in various water samples showed that acetone in moat water degraded completely after 18 days, whereas 70% of the acetone remained in pure water after 65 days, suggesting that microorganisms may play an important role in the degradation of carbonyl compounds in the environment.

CFD modelling of an annular reactor, application to the photocatalytic degradation of acetone

This study deals with the photocatalytic degradation of acetone, which is a typical pollutant of indoor air, in an annular photoreactor. The TiO 2 photocatalyst is deposited on a fiberglass support and irradiated by a commercial fluorescent tube placed at the center of the device. Acetone conversion extents up to 90% are obtained for low initial concentrations. Neither external mass transfer nor internal diffusion limitations are observed, and the annular reactor is first assimilated to a plug flow reactor. The Langmuir Hinshelwood model gives a good description of acetone degradation, and kinetic and adsorption parameters can be analytically deduced of the performed experiments. A Computational Fluid Dynamics description of the reactor is then proposed. The classical Navier–Stokes equations describe the flow in the free zone, whereas the Brinkman equation is used for the description of the flow in the porous zone. From an hydrodynamic point of view, a very good agreement between theoretical and measured Residence Time Distribution or upward velocities is obtained, testifying for the good description of the photocatalytic reactor. For a given illumination, the variations of acetone concentration inside the reactor can then be modelled. Comparison between theoretical and experimental outlet concentrations allows finally a better precision in the determination of the Langmuir Hinshelwood kinetic parameters. A relative difference of about 15% appears between the two sets of kinetic parameters (obtained assuming a plug flow or deduced from the CFD modelling). CFD simulations of photocatalytic reactor can thus address a better design of such air treatment devices.

Effect of Fluoride on the Photocatalytic Activity of Hollow TiO2 Microspheres prepared by Fluoride‐Mediated Self‐Transformation

AbstractPhotocatalytic activity of TiO2 is known to be enhanced by surface fluorination due to the enhanced production of free •OH radicals in solution. Recently, hollow TiO2 microspheres with enhanced photocatalytic activity was developed through fluoride‐mediated self‐transformation, in which the high photocatalytic activity in degradation of acetone was attributed to the fluoride‐induced enhanced crystallization of TiO2 without taking into account the effect of surface fluorination. This paper aims to re‐evaluate the effects of fluoride‐induced crystallization and surface fluorination on the photocatalytic activity of hollow TiO2 microspheres prepared by fluoride‐induced self‐transformation. Degradation of Brilliant Red X3B (X3B), an organic dye, was performed under different conditions to evaluate photocatalytic activity.

Photocatalytic degradation of gaseous acetone, toluene, and p-xylene using a TiO2 thin film

A nano-structured TiO2 thin film immobilized on glass springs was prepared by the sol-gel method, and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Acetone, toluene and p-xylene were chosen as common VOCs for a photocatalytic degradation study of both mixed and pure gases using the TiO2 thin film. Addition of hydrogen peroxide promoted activation of the catalyst during acetone degradation. The effects of gas flow rate and UV light wavelength were investigated with the pure gases. Gas flow rate greatly influenced the degradation. The highest degradation rates were 77.7% (at 3 L/min) for acetone, 61.9% (at 3 L/min) for toluene, and 55% (at 7 L/min) for p-xylene. A UV light wavelength of 254 nm provided greater degradation of the VOCs than 365 nm UV light. The degradation rates of p-xylene and acetone in the gas mixture were lower than those of pure p-xylene and acetone. The opposite trend was observed for toluene. Acetone, both in the mixed gas and pure, had the highest degradation efficiency. Acetone, toluene and p-xylene degradation followed Langmuir-Hinshelwood kinetics.

Photosensitization of Dye/TiO<sub>2</sub> Thin Films by Using Natural Dye of TCPP

The Dye-Sensitized TiO2 thin film fabricated by TiO2 nanoparticles is a novel technology with advantage in low cost, little pollution and simple in manufacturing process. The fiber-shaped reacting sites provide enlarged photo-sensing area of the TiO2 thin films. Natural dye of TCPP was applied to improve the photo absorbability in this study. Besides, a novel plasma surface activation technique employed on the thin film showed well performance compared with previous reports by heating methods. The SEM images demonstrate that the nano-TiO2 composites deposited on the fiber substrate. Degradation of acetone under 365 and 420 nm light irradiation were conducted to evaluate the photocatalytic ability of the TiO2 and TCPP/TiO2 thin films. While TiO2 thin films gel catalyst showed good photocatalytic performance with a high degradation efficiency of 99.9%, only about 80% conversion efficiency was achieved by the TCPP/TiO2 thin films reactor under 365 nm light irradiation. Although the TCPP dye on TiO2 nanoparticle shows beneficial reflection intensity in 420 nm, the acetone degradation capability of TiO2 and TCPP/ TiO2 thin films reactor decreased about 30% and 25% respectively compared with the degradation efficiency under 365 nm.

Degradation of Volatile Acetone by a Photocatalytic Reactor with TiO<sub>2</sub> Coated Sieve

The TiO2 thin films were coated on the 100 meshes stainless steel 304 (SS304) sieves by using the sol-gel method followed by a thermal treatment at 200oC. The prepared TiO2-coated sieves were then employed to setup a photocatalytic reactor for evaluating their abilities on the degradation of VOCs (volatile organic compounds). The UV lamp was enveloped with a cylinder TiO2-coated sieve and located in the center of the reactor. A VOCs diffusing tube was applied to yield acetone under water bath. The yielded gaseous acetone was enforced to pass through the TiO2-coated sieves and reacted by photocatalytic reaction. Both the inflow gas and off-gas were monitored by a PID (photoionization detector) sensor for calculating the treat efficiencies under various conditions. The results showed that the amorphous structure was observed on the TiO2 films after sol-gel method, whereas the crystalline anatase phase was found after annealing at 200oC. The SEM images showed that the surface morphology of TiO2 coated SS304 sieves was very similar to that of uncoated sieves, demonstrating a good uniformity and thin thickness of the sol-gel coating method derived in this work. It was observed that most volatile acetone (almost 100%) was removed after treated with the designed photocatalytic reactor under a high fed flow rate (0.5- 2.0 l/min). As compared with the control experiments (UV OFF test), the adequate photocatalytic abilities of this developed TiO2 coated sieves were demonstrated. With the advantages of high contacting area with VOCs, low headloss, durable substrate and easy maintenance, the TiO2-coated sieves possessed a high potential for applying on the photocatalytic degradation of indoor air pollutants.

Facile synthesis of ZnO/Zn2TiO4 core/shell nanowires for photocatalytic oxidation of acetone

ZnO/Zn2TiO4 core/shell nanowires were synthesized for the first time based on a solid–solid reaction of ZnO nanowires with a conformal shell of TiO2, which was deposited by a sol–gel method. The as-prepared samples were characterized by X-ray diffraction (XRD) analysis, transmission electron microscope (TEM) and environmental scanning electron microscope (ESEM). The surface photovoltage (SPV) spectra indicated that the as-synthesized ZnO/Zn2TiO4 core/shell nanowires exhibited more excellent photovoltaic activity than single ZnO nanowires. The enhanced photocatalytic activity of the ZnO/Zn2TiO4 core/shell nanowires was demonstrated by the degradation of acetone under UV light irradiation. As monitored by the in situ FTIR, a sequence of chemical steps could be extracted during the photocatalytic oxidation of gaseous acetone, which was firstly degraded into formate, and subsequently converted into CO and CO2. CO2 was partially converted to carbonate further.

Adsorption and Photoinduced Decomposition of Acetone and Acetic Acid on Anatase, Brookite, and Rutile TiO2 Nanoparticles

A comparative study of the adsorption and photoinduced degradation (PID) of acetone and acetic acid on thin films of anatase, brookite, and rutile TiO2 nanoparticles is presented. The materials were thoroughly characterized by a wide range of methods, including X-ray diffraction, transmission electron microscopy, and Raman and UV−vis spectroscopies. In situ FTIR transmission spectroscopy was used to follow adsorption and PID reactions. Molecular adsorption of acetone and acetic acid is observed on anatase and brookite, whereas significant dissociation occurs on rutile. It is inferred that adsorbate−surface interaction increases in the order anatase < brookite < rutile, favoring formation of bridge-bonded species on rutile (acetate and formate). Illumination with simulated solar light readily dissociates acetic acid and acetone on all TiO2 samples and produces polymorph-specific intermediate surface species, including acetate, formate, carbonate, and water. PID of surface coordinated acetate is rate determ...

Thick film titania on glass supports for vapour phase photocatalytic degradation of toluene, acetone, and ethanol

Thick film titania photocatalysts (50–100 μm, Degussa P-25 TiO 2) coated on two types of soda glass supports viz. beads (TiO 2/B) and Rasching rings (TiO 2/R) were tested in vapour phase photodegradation of toluene (63–383 g m −3), acetone (116–1161 g m −3), and ethanol (116–1161 g m −3) in a batch recirculation photoreactor at 60–70 °C. The concentrations of the substrates were 10- to 100-fold higher than those reported previously in similar investigations. The films were characterized by using SEM for morphology and EDX for elemental composition and mapping. Further, the effects of water vapour and shape and packing of the glass supports on the photodegradation kinetics were examined. The TiO 2 films on both the glass supports demonstrated high activity for photodegradation of toluene, acetone, and ethanol according to first-order kinetics. The apparent rate constants ( k a ) were found to vary from 1.48 × 10 −2 to 9.4 × 10 −3 g m −3 min −1 for the photodegradation of toluene on both TiO 2/B and TiO 2/R; 5.57 × 10 −2 to 1.29 × 10 −2 g m −3 min −1 for TiO 2/B and 6.70 × 10 −2 to 1.17 × 10 −2 g m −3 min −1 for TiO 2/R for acetone; and 2.14 × 10 −1 to 1.96 × 10 −2 g m −3 min −1 and 7.25 × 10 −2 to 3.51 × 10 −2 g m −3 min −1 using TiO 2/R for ethanol photodegradation. The efficient photodegradation of higher concentration of toluene, acetone, and ethanol was attributed to (i) availability of more amounts of active sites on the thick TiO 2 films for adsorption of VOCs, (ii) their photodegradation within ‘photoactive zone’ constituting outer surface layer of thick TiO 2 coating and (iii) higher reactor temperature. The SEM and EDX data suggest migration of sodium ions across glass/TiO 2 interface into ‘photoactive zone’ of the thick TiO 2 layers did not occur. The TiO 2/R appear to show better efficiency in comparison with TiO 2/B because their packing in the reactor allows for better illumination of catalysts surface.

Pivotal role of fluorine in enhanced photocatalytic activity of anatase TiO2 nanosheets with dominant (0 0 1) facets for the photocatalytic degradation of acetone in air

Surface-fluorinated anatase TiO2 nanosheets with dominant {001} facets were fabricated by a simple hydrothermal route in a Ti(OC4H9)4-HF-H2O mixed solution. The atomic ratios of fluorine to titanium (RF) exhibit an obvious influence on the structures and photocatalytic activity of TiO2 samples. In the presence of HF, TiO2 nanosheets can be easily obtained. With increasing RF, the relative anatase crystallinity, average crystallite size, pore size and percentage of exposed {001} facets increase, contrarily, BET specific surface areas decrease. All fluorinated TiO2 nanosheets exhibit much higher photocatalytic activity than Degussa P-25 TiO2 (P25) and pure TiO2 nanoparticles prepared in pure water due to the synergistic effect of surface fluorination and exposed {001} facets on the photoactivity of TiO2. Especially, at RF=1, the fluorinated TiO2 nanosheet exhibits the highest photocatalytic activity, and its photoactivity exceeds that of P25 by a factor of more than nine times.

Influence of hydrogen bonding upon the TiO 2 photooxidation of isopropanol and acetone in aqueous solution

This study investigates the aqueous photocatalytic degradation of small polar organic compounds (SPOCs) that bear hydrogen-bonding capabilities but do not readily adsorb to the TiO 2 catalyst. The effect of pH on the TiO 2 surface hydroxyl speciation and surface acid/base equilibria was used to elucidate the possible role of hydrogen-bonding interactions in the degradation of acetone and isopropanol in aqueous TiO 2 photocatalytic systems. The kinetic parameters describing the decomposition of these two model compounds were obtained by gas chromatographic analysis of their photoreaction systems and interpreted on the grounds of the Brönsted acid/base properties of the TiO 2 surface speciation and solute hydrogen-bonding numerical scales. The results showed that the fastest initial degradation rates of acetone and isopropanol occurred in a pH range where the optimal conditions for adsorption through hydrogen bonding to the TiO 2 surface and optimum concentration of hydroxyl radicals (OH ) coincide. The fastest degradation constants were observed at pH 6.04 and 8.61 for acetone and isopropanol, respectively. The hypothesis of hydrogen bonding to surface hydroxyl groups presented in this study challenges the common assumption that these model compounds do not adsorb to surface sites, and that their oxidative pathways of degradation only occur via homogeneous-phase reaction with free OH radicals.

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.

Degradation of Acetone and MEK Using a Biofilter Packed with a Ceramic-type Medium

Degradation of Acetone and MEK Using a Biofilter Packed with a Ceramic-type Medium

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.

Gas phase degradation of acetone using a TiO2 photocatalyst supported on a polyester fabric

The feasibility of using a titanium dioxide photocatalyst supported on polyester fabric for the removal of low concentrations of VOCs was evaluated. A series of experiments was conducted to evaluate photocatalytic efficiency in terms of the following: catalytic activity; reaction temperature; influence of mass transfer and type of VOC.

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.