Methyl Ethyl Ketone Degradation Research Articles

Critical role of reactive species in the degradation of VOC in a plasma honeycomb catalyst reactor

This paper reports the nature of the reactive species formed and their role in the degradation of methyl ethyl ketone (MEK) using plasma catalysis in a honeycomb monolith reactor. A series of experiments were performed using plasma with different discharge gases (i.e., N2, O2, or air) in the presence of the honeycomb catalyst. A novel method is introduced to identify the reactive species that form during the plasma process and their contribution. We found the role of O atoms to be dominant compared with that of other reactive species in the plasma catalytic removal of MEK. In addition, the effect of introducing O3 over the catalyst surface was investigated, with oxygen activation resulting from surface chemisorption mainly contributing to MEK oxidation. Analysis of the byproducts enabled us to propose possible reaction mechanisms for the oxidation of MEK in the air plasma catalytic reactor.

Kinetic modeling of the photocatalytic degradation of methyl ethyl ketone in air for a continuous-flow reactor

This paper reports the study on kinetic modeling of photocatalytic degradation of methyl ethyl ketone (MEK) using TiO2 coated on silica fiber felts. Two different mathematical models, ideal plug flow model and axially dispersed plug flow model (dispersion model), were used to simulate the performance of the PCO reactor. Six kinetic rate equations on the basis of Langmuir-Hinshelwood (L-H) expression were examined to find the best model that fits the experimental data. Moreover, the light intensity distribution on the photocatalyst surface was simulated using the linear source spherical emission model (LSSE) and validated with the experimental data. The Beer-Lambert model was also applied to demonstrate the diminishment of light intensity in the PCO filter. For model prediction validation, a series of experiments was carried out in a bench-scale continuous flow reactor at different concentrations (0.1–1 ppm), relative humidities (17–67%), flow rates (10–30 L/min), and light intensities (7–23.5 W/m2). In addition, adoption tests with MEK at various concentrations (0.25–1 ppm) and relative humidities (15–50%) were conducted under dark condition. Formaldehyde, acetaldehyde, acetone, and propionaldehyde were identified (through HPLC analysis) as by-products of the MEK PCO reaction. Owing to higher concentrations of formaldehyde and acetaldehyde, aldehyde group was considered as the main by-products. The result of carbon balance indicated that 7.2% of MEK mineralized to CO2 (measured by GC-FID) and around 10.8% of that was converted to by-products (for 18.4% removal efficiency). Evaluation of different kinetic rate expressions revealed that the unimolecular L-H model considering inhibitive effect of water vapor and by-products for adsorption provided the best fit. The dispersion model combined with this rate expression had a higher accuracy at all operating conditions while the plug flow model failed to predict the PCO performance at various intensities and air velocities. Evaluation of mass transfer was also performed, and it was concluded that the mass transfer effect on the PCO process is not dominating step; consequently, the PCO reaction is the rate-limiting process.

Carbon-doped TiO2 film to enhance visible and UV light photocatalytic degradation of indoor environment volatile organic compounds

Abstract Carbon-doped P25, a visible-light-driven photocatalyst, was prepared to remove methyl ethyl ketone (MEK) from the indoor air environment. The effect of key parameters such as carbon content, relative humidity and light type on the photocatalyst efficiency, reaction rate and by-products generation rate were evaluated. C-doped P25 photocatalysts coated on nickel foam enhanced photocatalytic degradation and the reaction rate of gas-phase MEK under visible and UV light, compared with a commercial P25 coated on the same substrate material. The results indicate that the photocatalytic degradation efficiency and the reaction rate of all examined photocatalysts under UV light are higher than visible light. All the experiments were carried out in two continuous reactors with a small residence time (0.025 s), 2.95 mg/m3 (1000 ppb) inlet contaminant concentration and at four different relative humidity levels (0, 20, 40 and 60 %). As a result, the optimum relative humidity was 20 % and 40 % for visible-PCO and UV-PCO of C-doped P25, respectively. Moreover, C-P25-0.1 % showed the highest MEK degradation under all tested conditions. The removal efficiency was enhanced from 77 % to 94 %, when three layers C-P25-0.1 % photocatalyst, was under UV light, and increased from 50 % to 67 % under visible light. Moreover, the by-product generation was considerably decreased for three-layer C-P25-0.1 % photocatalyst.

Effect of surface fluorination of P25-TiO2 coated on nickel substrate for photocatalytic oxidation of methyl ethyl ketone in indoor environments

Volatile organic compounds (VOCs) degradation via photocatalytic oxidation process (PCO) has been employed for air treatment in indoor environment application. However, the performance of PCO is hindered at high humidity conditions, due to the superhydrophilic surface of TiO2 and competition between VOCs and water molecules for adsorption on surface’s active sites. Herein, the photocatalytic activities of P25 and surface fluorinated P25 (F-P25) coated on nickel foam were evaluated for degradation of methyl ethyl ketone (MEK). Surface fluorination enhanced the UV light absorption and reduced the charge carrier recombination. Therefore, the photocatalytic efficiency and by-product generation rate of F-P25 are investigated in a continuous reactor operating at different inlet contaminant concentrations (200–1000 ppb), relative humidity levels (0–80%), light intensities (37 and 28 W/m2) and residence time (0.013-0.076 s). Results indicated that the surface fluorination of P25 enhanced the PCO efficiency of MEK removal in all tested conditions, compared to P25. The MEK removal efficiency under UV irradiation for three-layer and one-layer of F-P25 photocatalyst are 92% and 73%, respectively. Accordingly, by-products generation was considerably decreased using three layers of F-P25 photocatalyst. Moreover, the reaction mechanism for the photocatalytic oxidation of MEK is also proposed. The results of this research will ultimately lead to enhancing the efficiency of PCO process, especially in high humid condition.

On the role of BmimPF6 and P/F- containing additives in the sol-gel synthesis of TiO2 photocatalysts with enhanced activity in the gas phase degradation of methyl ethyl ketone

The role of phosphate and fluoride ions brought by the BmimPF6 ionic liquid via hydrolysis during the sol gel synthesis of TiO2 has been investigated by replacing BmimPF6 with phosphorous- and fluorine-containing additives, phosphoric acid (PA) and sodium fluoride (NaF), respectively. Correlation between the physico-chemical properties and the photocatalytic behavior of the synthesized TiO2 materials was established. High crystallinity anatase TiO2 photocatalysts with controlled crystallite size and shape resulting from P/F-induced modifications displayed strongly improved photocatalytic activity and mineralization yield under UV-A illumination in the degradation of methyl ethyl ketone (MEK) taken as model Volatile Organic Compound (VOC), compared to the TiO2 Aeroxide P25 reference and sol-gel TiO2 counterpart synthesized in absence of any BmimPF6. We showed that the BmimPF6 ionic liquid could be efficiently substituted by cheap PA and NaF additives in an adequate ratio in the sol-gel synthesis for synthesizing TiO2 photocatalysts without altering the main physico-chemical properties and the photocatalytic activity. We proposed a similar synthesis mechanism in both ionic liquid- and P/F-assisted sol-gel syntheses of TiO2, involving a combined role of phosphate and fluoride ions. The reaction of phosphates with titanium hydroxide network in the early stage of the sol-gel synthesis resulted in a size control of TiO2 crystallites and thus in higher specific surface area, in favor of a higher MEK conversion rate, while the fluoride ions were hypothesized to cause an anisotropic TiO2 crystal growth during the aging step of the sol gel synthesis, in favor of a higher selectivity to CO2 through a favored adsorption of intermediate products of MEK degradation on the exposed TiO2 {001} facets.

Complete Genome of Rhodococcus pyridinivorans SB3094, a Methyl-Ethyl-Ketone-Degrading Bacterium Used for Bioaugmentation.

Here, we present the complete genome of Rhodococcus pyridinivorans SB3094, a methyl-ethyl-ketone (MEK)-degrading strain used for bioaugmentation relating to the treatment of wastewater contamination with petrochemical hydrocarbons. The genome highlights important features for bioaugmentation, including the genes involved in the degradation of MEK.

Functional characterization and application of a tightly regulated MekR/P mekA expression system in Escherichia coli and Pseudomonas putida

A methyl ethyl ketone (MEK)-inducible system based on the broad-host-range plasmid pBBR1MCS2 and on the P mekA promoter region of the MEK degradation operon of Pseudomonas veronii MEK700 was characterized in Escherichia coli JM109 and Pseudomonas putida KT2440. For validation, β-galactosidase (lacZ) was used as a reporter. The novel system, which is positively regulated by MekR, a member of the AraC/XylS family of regulators, was shown to be subject to carbon catabolite repression by glucose, which, however, could not be attributed to the single action of the global regulators Crc and PtsN. An advantage is its extremely tight regulation accompanied with three magnitudes of fold increase of gene expression after treatment with MEK. The transcriptional start site of P mekA was identified by primer extension, thereby revealing a potential stem-loop structure at the 5' end of the mRNA. Since MekR was highly insoluble, its putative binding site was identified through sequence analysis. The operator seems to be composed of a 15-bp tandem repeat (CACCN5CTTCAA) separated by a 6-bp spacer region, which resembles known binding patterns of other members of the AraC/XylS family. Subsequent mutational modifications of the putative operator region confirmed its importance for transcriptional activation. As the -35 promoter element seems to be overlapped by the putative operator, a class II activation mechanism is assumed.

Modeling of the photocatalytic degradation of methyl ethyl ketone in a fluidized bed reactor of nano-TiO2/γ-Al2O3 particles

Gas phase photocatalytic degradation of methyl ethyl ketone (MEK) using nano-TiO2 supported γ-Al2O3 adsorbent was studied in a Fluidized Bed Photo-Reactor (FBPR). The objective was to simulate photocatalytic degradation of MEK in the FBPR. The experiments were conducted in order to investigate the effect of operating parameters such as relative humidity (RH), MEK concentration, and superficial gas velocity on MEK degradation. In order to simulate the performance of the FBPR, the kinetic sub-model and the hydrodynamic sub-model were coupled together and solved simultaneously. The Langmuir–Hinshelwood (LH) kinetic model was adopted for photocatalytic degradation of MEK and its kinetic parameters were determined experimentally. The simple two-phase and dynamic two-phase models were considered as the hydrodynamic sub-models and their validity was investigated through comparing the simulation data and the experimental results. It was observed that the dynamic two-phase model has more validity than the simple two-phase; therefore, the dynamic two-phase model was selected as the hydrodynamic sub-model to predict the performance of the FBPR. The model predictions were compared with the experimental results of this study and the experimental data reported in the literature. Close agreement was found between the model and the experimental data. The modeling and simulation results of this study can be used to predict the performance of the fluidized bed photo-reactor.

Performance improvement of TiO<SUB align=right>2 supported on adsorbents for photocatalytic degradation of MEK in air

Photocatalytic degradation of Methyl Ethyl Ketone (MEK) was carried out in gas phase using TiO2 supported on different adsorbents. Based on size and surface area, three different adsorbents, montmorillonite, β-zeolite and MCM-41 were tested. A fluidised bed annular photoreactor fitted with either 254 or 365 nm lamps was used for the photodegradation studies. The removal rates of MEK were higher for the catalysts supported on the adsorbent as compared to bare TiO2 (Degussa P25 and sol-gel TiO2) due to both improved adsorption and photocatalytic degradation. The photocatalytic activity of the supported TiO2 was maximum around 50 wt.% loading of TiO2. Among all the adsorbents tested, montmorillonite showed better removal rate than MCM-41 and β-zeolite. Some limited experiments were conducted with Trichloroethylene (TCE) to evaluate the effect of polarity of the organic compound on overall degradation using the supported catalysts.

Remediation of olfactory pollution by photocatalytic degradation process: Study of methyl ethyl ketone (MEK)

The photocatalyzed oxidation of gas-phase contaminants in air is being more and more explored regarding the possible applications: decontamination, deodorization and purification of enclosed atmospheres. In the present work, the photocatalytic degradation of a typical malodorous pollutant of indoor air: methyl ethyl ketone (MEK) has been investigated by using an annular photoreactor. The annular photoreactor was modelled by a cascade of heighten elementary continuously stirred tank reactors. The influence of several kinetic parameters such as pollutant concentration, oxygen content, humidity content and incident light irradiance has been studied. The Langmuir–Hinshelwood model has been verified for MEK. The by-products of MEK photocatalytic degradation have been identified by GC/MS and acetaldehyde was found to be the main gaseous intermediate. Acetaldehyde thus has been taken into account in the general Langmuir–Hinshelwood model to evaluate the possible competition of adsorption between acetaldehyde and MEK. A mechanistic pathway is then proposed for the photocatalytic degradation of MEK.

Degradation characteristics of methyl ethyl ketone by Pseudomonas sp. KT-3 in liquid culture and biofilter

With ketone pollution forming an ever-growing problem, it is important to identify a ketone-degrading microorganism and establish its effect. Here, a methyl ethyl ketone (MEK)-degrading bacterium, Pseudomonas sp. KT-3, was isolated and its MEK degradation characteristics were examined in liquid cultures and a polyurethane-packed biofilter. In liquid cultures, strain KT-3 could degrade other ketone solvents, including diethyl ketone (DK), methyl propyl ketone (MPK), methyl isopropyl ketone (MIPK), methyl isobutyl ketone (MIBK), methyl butyl ketone (MBK) and methyl isoamyl ketone (MIAK). The maximum specific growth rate ( μ max) of the isolate was 0.136 h −1 in MEK medium supplemented with MEK as a sole carbon source, and kinetically, the maximum removal rate ( V m) and saturation constant ( K m) for MEK were 12.28 mM g −1 DCW h −1 (DCW: dry cell weight) and 1.64 mM, respectively. MEK biodegradation by KT-3 was suppressed by the addition of MIBK or acetone, but not by toluene. In the tested biofilter, KT-3 exhibited a > 90% removal efficiency for MEK inlet concentrations of around 500 ppmv at a space velocity (SV) of 150 h −1. The elimination capacity of MEK was more influenced by SV than by the inlet concentration. Kinetic analysis showed that the maximum MEK removal rate ( V m) was 690 g m −3 h −1 and the saturation constant ( K m) was 490 ppmv. Collectively, these results indicate the polyurethane sequencing batch biofilter with Pseudomonas sp. KT-3 will provide an excellent performance in the removal of gaseous MEK.

A comprehensive chemical mechanism for the oxidation of methylethylketone in flame conditions

The improvement of the thermal oxidizers commonly used in the industry to treat the gaseous effluents and thus to limit the rejection of pollutants in the atmosphere requires knowledge of the oxidation processes of volatile organic compounds (VOCs). Methylethylketone (MEK) is a representative VOC and it has been chosen also because of the lack of kinetic data available in the literature concerning the ketones oxidation. Premixed laminar stoichiometric CH 4/MEK/O 2/N 2 flat flames have been studied at low-pressure by varying the percentage of seeded MEK up to 3%. The experimental measurements, obtained by coupling microprobe sampling with gas chromatography—mass spectrometry (GC/MS) analysis, have been compared with the predictions of a detailed mechanism. The developed mechanism includes 29 oxygenated species involved in 140 reversible reactions specific to the MEK thermal degradation: it takes into account the first steps of the MEK oxidation and the oxidation processes of the main oxygenated intermediate compounds as acetone, methanol, ethanol, acetaldehyde and propanal. When the quantity of MEK added to the methane flame varies, the increase of C 2 and C 3 hydrocarbon species and the evolution of oxygenated intermediates are well reproduced by the model. The sensitivity analysis points out the main reactional pathways involved in the thermal degradation of MEK in flame conditions and reveals the important production of methyl and ethyl radicals which lead, by recombination processes, to the formation of the oxygenated intermediate compounds.

Experimental and Kinetic Analysis of the Thermal Degradation of the Methylethylketone in Methane / Air Flames UMR CNRS 8522 “Physicochimie des Processus de Combustion”.

The experimental study of the thermal degradation of methylethylketone (MEK) in flame conditions is undertaken to provide an experimental data base concerning Volatile Organic Compounds (VOCs) oxidation. The experimental set-up consists of the coupling of microprobe sampling with gas chromatography and mass spectrometry analysis. Temperature measurements are realized by the coated thermocouple technique. The addition of MEK to a reference methane / air flame induces (1) an enhancement of the C2 and C3 hydrocarbon oxidation pathways which points out the main role of CH3 and C2H5 radicals, and (2) the formation of oxygenated intermediate compounds such aldehydes (CH2O, CH3CHO. CH3CH2CHO), alcohols (CH3OH, CH3CH2OH) and ketones (CH3COCH3, CH3COCHCH2, CH3CH2COCH2CH3, CH3COCH2CH2CH3). The peak mole fraction of these intermediate species increases with the amount of MEK added to the methane / air flame. The experimental results are discussed to point out the kinetic processes involved in the high temperature oxidation of MEK which may contribute to the development of a detailed chemical mechanism.

Equilibrium, Kinetics, and Column Dynamics of Methyl Ethyl Ketone Biodegradation

Equilibrium and kinetic studies of methyl ethyl ketone (MEK) adsorption in compost and granular activated carbon (GAC), the reaction rate and selectivity of microorganisms for MEK biodegradation, and the role of the adsorption capacity of the support medium on biofilter dynamics are investigated in this study. Experiments on MEK degradation using biofilters with either Rhodococcus sp. or a mixed culture showed comparable results, indicating no advantage of a pure culture of Rhodococcus sp. The equilibrium isotherm of MEK in compost is linear in the entire range of concentration typically encountered in biofilters, but on GAC the isotherm is nonlinear. Investigation on adsorption kinetics suggests that the mass transfer is macropore-controlled in both compost and GAC. However, in compost the transport appears to be by molecular diffusion, whereas in GAC it is by a combination of molecular, Knudsen, and surface diffusion. Experimental results show that GAC is better than compost in terms of pollutant removal and handling of the fluctuating input load. A linear driving force approximation is used to describe the transport of solute from the gas phase to the support phase. The resulting linear driving force biofiltration model, using independently measured equilibrium and kinetic parameters, appears adequate for describing the experimental results of biofilter dynamics.