Adsorption Of Methyl Ethyl Ketone Research Articles

An investigation on catalytic performance and reaction mechanism of RuMn/meso-TiO2 derived from RuMn intermetallic compounds for methyl ethyl ketone oxidation

In this work, we first used the oil-phase co-reduction strategy to synthesize the RuxMny (Mn/Ru molar ratio (y/x) = 7 : 20, 21 : 25, and 17 : 10) intermetallic compounds, then used the KIT-6-templeting method to prepare mesoporous titania (meso-TiO2), and finally used the impregnation method to generate the RuxMny/meso-TiO2 (Ru loading = 0.60–0.79 wt%) catalysts. Various techniques were used to measure physicochemical properties of the samples, and their catalytic performance was determined for methyl ethyl ketone (MEK) oxidation. It is found that the RuxMny/meso-TiO2 samples possessed a three-dimensionally ordered mesoporous structure, a surface area of 71–173 m2/g, and a uniform RuxMny particle size of 2.3–2.9 nm. Among all of the samples, Ru25Mn21/meso-TiO2 exhibited the best catalytic performance and good hydrothermal stability: the temperatures at MEK conversions of 10, 50, and 90 % were 131, 226, and 248 °C at a space velocity of 20,000 mL/(g h), with the apparent activation energy, specific reaction rate at 160 °C, and turnover frequency (TOF) at 160 °C being 73 kJ/mol, 41.73 mmol/(gRu s), and 4.20 s−1, respectively. In addition, introduction of 5 vol% moisture to the reaction system exerted a positive effect on catalytic activity of Ru/meso-TiO2 or Ru25Mn21/meso-TiO2 at higher temperatures. Such good performance of the Ru25Mn21/meso-TiO2 sample was related to its well dispersed Ru25Mn21 nanoparticles, high adsorbed oxygen species concentration, active surface lattice oxygen, high MEK adsorption capacity, good redox ability, and strong interaction between Ru25Mn21 and meso-TiO2. We propose that MEK might be oxidized by the adsorbed oxygen and/or surface lattice oxygen species via in turn formation of 2,3-butanedione, acetaldehyde, acetic acid, formaldehyde, and formic acid, all of which were finally converted to water and carbon dioxide.

Synthesis and characterization of electrospun PAN-based activated carbon nanofibers reinforced with cellulose nanocrystals for adsorption of VOCs

Electrospun Polyacrylonitrile/Cellulose nanocrystal (PAN-CNC) nanofibers with uniform diameter and smooth morphology were prepared. The nanofibers were stabilized, then activated to produce activated carbon nanofibers (ACnFs) and their physical and chemical properties were characterized. Last, the adsorption properties of ACnFs were tested for adsorption of methyl ethyl ketone (MEK) and cyclohexane. Scanning electron microscopy revealed that the addition of CNCs improves fiber uniformity and decreases fiber diameter due to enhanced electrical conductivity of electrospinning solutions. The addition of CNCs had minimal effect on fibers thermal stability; however, it brought large improvement in tensile strength. The pore size distribution indicated large volumes of micropores and mesopores in all samples. The maximum surface area and total pore volume were respectively 3497 m2/g and 2.62 cm3/g for 25%PAN-75%CNC nanofibers. The adsorption capacity for MEK and cyclohexane correlated well with the surface area of ACnF, reaching a maximum value of 1.7 and 1.8 gadsorbate/gadsorbent for MEK and cyclohexane, respectively. Compared to commercial activated carbons fiber and beads, the prepared ACnF exhibited higher capacities and faster adsorption kinetics due to larger surface area, higher mesoporosity, and better mass transfer. These results indicate that using CNC improves the mechanical and adsorption properties of electrospun PAN nanofibers. This article, for the first time, puts forward CNC reinforced activated carbon nanofibers as suitable adsorbents for environmental remediation applications.

Adsorption performance of standard biochar materials against volatile organic compounds in air: A case study using benzene and methyl ethyl ketone

Recently, biochars have been proposed as highly efficient and low-cost media for the adsorptive removal of various hazardous compounds. However, there is a dearth of literature focusing on adsorption performance of biochars against gaseous volatile organic compounds (VOCs). In light of this limitation, the adsorption performances of 12 standard biochars made of six different raw materials (i.e., Miscanthus straw pellets, oil seed rape straw pellets, rice husk, sewage sludge, soft wood pellets, and wheat straw pellets) at two pyrolysis temperature conditions (i.e., 550 °C and 700 °C) were investigated against two model gaseous VOCs (i.e., benzene and methyl ethyl ketone (MEK)) at 1 Pa each. The breakthrough volume (BTV) and partition coefficient (PC) of benzene at 10% BTV, when measured for all these biochars, varied from 1.4 to 10 L atm g−1 and 6.E-04 to 1.4E-02 mol kg−1 Pa−1, respectively. Similarly, their counterpart values for MEK were 1.8 to 40 L atm g−1 and 1.E-03 to 2.E-03 mol kg−1 Pa−1, respectively. The largest adsorption capacity values for benzene (2.9 mg g−1) and MEK (43 mg g−1) were observed from the soft wood pellet biochar prepared at 700 °C (SWP700) and rice husk biochar prepared at 550 °C (RH550), respectively. The results indicate that most biochars adsorbed MEK preferentially over benzene. The adsorption of MEK appeared to be primarily influenced by surface features and composition of each specific biochar, while that of benzene was proportionate to their surface area. Overall, the results of this investigation are expected to help establish technical standards for effective removal of gaseous VOCs by biochars.

Adsorption–desorption characteristics of methyl ethyl ketone with modified activated carbon and inhibition of 2,3-butanediol production

Activated carbon (AC) is seldom applied for recovering ketone-based volatile organic compounds because of safety concerns. Adsorption of methyl ethyl ketone (MEK) with AC is a highly exothermic reaction that potentially causes fires in AC beds. Moreover, 2,3-butanediol (BDO) is produced in the desorbed solvent, causing yellowing and odor of the recovered solvent. This study applied a continuous adsorption–desorption apparatus for evaluating the operating capacities and BDO concentration in recovered MEK containing modified and original ACs. AC-1 (TAKETA- G2X) was used as the target for modification. The experimental results indicate that using MgO as the modifier increases the ignition point by 12°C and that applying KNO3 as the modifier reduces the AC ignition point by 28°C (compared with AC-1). The BDO concentration of the desorbed MEK solvent can be reduced by increasing the loading of the modifying agent (Ethanolamine) (Im-1: 3.1 wt%; Im-5: 6.2 wt%). Moreover, applying the AC pretreated with nitrogen (Im-6) as adsorbent significantly reduces the BDO concentration (from 0.123 wt% to 0.073 wt%). Because desorption and purging procedures were performed in N2 atmospheres, the BDO concentrations of the desorbed MEK solvents were relatively low and ranged from 0.032 wt% to 0.043 wt%. When the MEK concentration was reduced to 2000 ppm, lower BDO concentrations (0.012–0.022 wt%) were measured in the recovered MEK solvent. The way to modify activated carbon and a better desorbing sequence to effectively inhibit the oxidation of MEK to BDO are developed. The results obtained indicate that the BDO concentration in the desorbed solvent was lower than the original MEK solvent (0.023 wt%). Different approaches can be applied simultaneously to achieve high inhibition effects; however, carbon adsorption performance may be negatively affected.Implications: The study is motivated to improve the quality of recovered solvent and reduce fire hazards, particularly when AC is applied for adsorbing a ketone-based solvent (e.g., MEK). The experimental results indicate that the BDO concentration in the recovered solvent can be reduced and the ignition point of AC can be increased by modifying the AC with an appropriate agent.

Adsorption of methyl ethyl ketone onto poly(vinyl alcohol)(PVA)/peat/organoclay composite beads in aqueous solution

A new type of poly(vinyl alcohol)(PVA)/peat/organoclay composite beads was prepared. This composite bead was a porous spherical particle with a diameter of 3.0–5.0 mm and a porosity of about 50%. The oragnoclay is prepared by hexadecyl trimethyl ammonium bromide (HDTMA) exchanged clay. The dynamic adsorption behavior between methyl ethyl ketone (MEK) and this composite bead was investigated. The adsorption process occurs in two stages with external mass transport occurring in the early stage and intraparticle diffusion occurring in the later stage. The rate of MEK diffusion in the external mass transport process and the intraparticle diffusion process in the adsorption temperature 20–35 °C was 3.28–76.98 × 10−8 cm2/s and 1.62–3.17 × 10−7 cm2/s, respectively. The rate of MEK diffusion in both processes was concentration independent, and it increased with increasing the adsorption temperature. Langmuir isotherm adsorption model was more suitable for describing the adsorption equilibrium of MEK. The calculated Q values in the adsorption temperature 20–35 °C were 5.90–22.78 mg/g composite bead. The adsorption capacity of this composite bead increased with increasing the adsorption temperature. The adsorption process was physical adsorption, endothermic and non-spontaneous process.

Thermal transformation of polyacrylonitrile deposited on SBA-15 type silica

Thermogravimetry, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used for the studying of thermally induced structural changes of polyacrylonitrile (PAN) deposited on the surface of SBA-15 type mesoporous silica. Polymer was introduced onto the support by the precipitation polymerization of acrylonitrile in aqueous suspension of SBA-15. Low temperature transformation (to 723 K) of the deposited PAN was analyzed. It was found that at about 523 K, exothermic cyclization of polymer chains to the so-called ladder form of PAN occurred. However, the total cyclization of PAN required higher carbonization temperatures, at which gradual dehydrogenation followed by graphitization was initiated. XPS revealed that the cyclic form of PAN and a relatively large amount of carbonyl species, formed during the carbonization of the PAN/SBA-15 composite at 623 K, were responsible for the high sorption capacity in the methyl–ethyl ketone (MEK) vapor elimination. The efficiency in the MEK adsorption was also influenced by the content of PAN-derived carbon deposited on the SBA-15 surface.

Competition among Mixed Adsorbates Affecting the Adsorption of Gaseous Methyl Ethyl Ketone by Hydrophobic Molecular Sieve

Internal circulation cabinets, equipped with adsorbents for emitted volatile organic compounds (VOCs), are extensively used to store organic solvents in Taiwanese university and hospital laboratories. This work evaluates how ketone and isopropanol (IPA) respectively influence the methyl ethyl ketone (MEK) adsorption capacity of a hydrophobic molecular sieve (MS) with a high Si/Al ratio of 1000, HiSiv 1000, manufactured by UOP LLC Corporation, USA. Experimental results for MEK at concentrations from 113 to 2815 ppm reveal that the MEK adsorption capacity is linearly expressed as the natural logarithm of adsorption time (ln (t)) at the constant temperature 27 o C and relative humidity 72 ± 3%. The variations in the simulated MEK equilibrium adsorption capacity (Qe, g MEK/g MS) and concentration (C, ppm) are closely fitted using a Langmuir isotherm. Lower VOC concentration ratios less than 0.17 for mixing acetone and IPA respectively with MEK rarely affect the MEK adsorption by HiSiv 1000. However, the effect of competitive adsorption, which evidently reduces the adsorption capacity of MEK, is related to the higher mixture concentration ratio (> 0.80) of IPA to MEK. The experimental results show that the hydrophobicity characteristics of MEK, acetone and IPA were responsible for variation in adsorption capacity of hydrophobic molecular sieve. Working parameters of adsorbent materials in the internal circulation cabinet have been also provided for preventing breakthrough of VOC adsorption by the molecular sieve.

Adsorption of methyl ethyl ketone and trichloroethene from aqueous solutions onto silicalite fixed-bed adsorbers

This work addresses the adsorption of methyl ethyl ketone (MEK) and trichloroethene (TCE) from aqueous solutions on agglomerated silicalite. Results from both equilibrium and fixed-bed adsorption studies in aqueous solutions are given. The breakthrough curves of MEK could be described adequately with a bidisperse model. It was observed that the mass transfer of MEK is controlled by both the external and the macropore transport. The breakthrough curves of TCE are also adequately described with the same model, for which the micropore resistance was the most important one. The thermal regeneration of the agglomerated silicalite loaded with MEK by passing a purging gas through the bed (nitrogen and air) was also studied. No decrease of the adsorption capacity with the number of regeneration cycles was observed.

Adsorption of methyl ethyl ketone and trichloroethene from aqueous solutions onto activated carbon fixed-bed adsorbers

Adsorption of methyl ethyl ketone and trichloroethene from aqueous solutions onto activated carbon fixed-bed adsorbers

Adsorption of methyl ethyl ketone and trichloroethene from aqueous solutions onto activated carbon fixed-bed adsorbers

This work addresses the adsorption of methyl ethyl ketone (MEK) and trichloroethene (TCE) from aqueous solutions on activated carbon. Results from both equilibrium and fixed-bed adsorption studies in aqueous solutions are given. For TCE, the sorbent is saturated for liquid concentrations near its solubility, which can be explained in terms of a pore volume filling mechanism. MEK adsorbs less than TCE for the same liquid concentration. A specific adsorption mechanism onto basic surface groups seems more plausible for this solute, which explains the plateau of the adsorbed concentration observed at liquid concentrations much lower than its solubility. The fixed-bed adsorption dynamics of both solutes can be described with the pore diffusion model, considering external mass transfer and internal diffusion inside the activated carbon. The thermal regeneration of the activated carbon loaded with MEK by passing a purging gas through the bed (nitrogen and air) is also studied.

The adsorption of benzene and methylethylketone onto activated carbon: thermodynamic aspects

The adsorption of volatile organic compounds (VOCs), exemplified by benzene and methylethylketone (MEK), onto seven different types of activated carbon was investigated. Results show that for benzene adsorption the adsorption characteristic energy, enthalpy, free energy and entropy are in the range 17.12–36.86, −20.8 to −44.7, −11.89 to −16.22 kJ/mole and −29.4 to −85.3 J/mole/K, respectively. For the adsorption of MEK, the adsorption characteristic energy, enthalpy, free energy and entropy are in the range 14.47–32.34, −18.3 to −40.8, −10.78 to −15.56 kJ/mole and −24.8 ∼ −60.3 J/mole/K, respectively. The adsorption enthalpy can be calculated indirectly from statistical thermodynamic method and directly from the immersion enthalpy method. The adsorption characteristic energy is calculated by the Dubinin–Astokhov equation. The free energy is calculated by the measured equilibrium adsorption constant.

Ozonation of activated carbon and its effects on the adsorption of VOCs exemplified by methylethylketone and benzene

Ozonation can modify the surface property of an activated carbon such as specific surface area, pore volume, and functional group. Results indicate that ozonation can increase the specific surface area of an activated carbon from 783±51 to 851±25 m 2 /g due in part to increasing micropores (those below 15 Å). However, there is no change in macropore and mesopore upon ozonation. The amount of oxygen functional group (OFG) increases from 197±4 to 240±4 μeq/g , mostly in hydroxyl and carboxyl groups upon ozone treatment. These oxygen-containing functional groups are stable in the temperature range 30–250 °C, but begin to decompose when temperature increases beyond 300 and 350 °C. When the temperature reaches 1200 °C, all OFGs virtually disappear. The effect of ozone treatment on the adsorption of volatile organic carbon (VOC) was exemplified by methylethylketone (MEK) and benzene. The adsorption density of MEK and benzene by ozone treated activated carbon (AC(O 3)) are greater than that by the untreated (AC), with MEK being more adsorbable than benzene. Results of factorial analysis indicate that physical characteristics, namely, micropore, BET surface area, pore diameter (PD), micropore volume (MV) play an important role on benzene and MEK adsorption.

Adsorption and Electrothermal Desorption of Hazardous Organic Vapors

In 1997, 6.04 x 10\u8 kg of hazardous air pollutants were emitted into the atmosphere from the United States. A bench-scale activated-carbon fiber-cloth adsorption, electrothermal desorption, and condensation system was designed, built, and operated to demonstrate its ability to capture and recover organic hazardous air pollutants from airstreams. The annular-cartridge configuration of the activated carbon fiber cloth allows low pressure drop and rapid electrothermal regeneration. Adsorption and electrothermal desorption cycling of the system with an airstream containing 1,000 ppmv methyl ethyl ketone (MEK) resulted in closure within 8% by mass. Competitive adsorption between water vapor and MEK reduced MEK adsorption capacity 43% as relative humidity of the gas increased from 4 to 90% at 22°C dry-bulb temperature. Increasing the dry-bulb temperature of the gas stream by 10°C at a constant dew-point temperature resulted in a 37% increase in MEK adsorption compared to the high relative humidity test case, while allowing the water vapor to penetrate the adsorber. The automated system achieves MEK capture efficiency >99.9% by mass while recovering the liquid MEK for reuse.

Diffusivity of microporous carbon for benzene and methyl-ethyl ketone adsorption

Kinetic studies results indicate that the pore diffusion coefficient is from 10 −6 to 10 −8 cm 2/sec for both benzene and MEK in the temperature range of 30–120°C. Under similar adsorbate concentration, MEK exhibits an effective pore diffusion coefficient greater than benzene. This may be attributed to its smaller molecular size being a polar molecular structure attracted to the activated carbon surface. In general, the effective diffusivity of MEK was greater than benzene under the same temperature and similar concentration. The influence of influent concentration on effective diffusion coefficient at low temperature is greater than that at high temperature.

Adsorption of methyl‐ethyl ketone vapor onto zeolites

Volatile organic compounds (VOCs) emitted from industries are often removed by carbon or zeolite adsorption. This study presents the adsorption capacity of methyl‐ethyl ketone (MEK) vapor (inlet concentration = 100 ∼ 1500 ppm) onto six different types of zeolites as a function of their properties including surface area, pore volume and Si/Al ratio. The results indicate that the MEK adsorption capacities depend on the type of zeolite, specifically on Si/Al ratio. The measured adsorption data fit reasonably well with Langmuir and Freundlich equations.

Adsorption of methyl ethyl ketone on mercury

Adsorption of methyl ethyl ketone on mercury