Adsorption Of Ethylene Oxide Research Articles

A DFT and QTAIM insight into ethylene oxide adsorption on the surfaces of pure and metal-decorated inorganic fullerene-like nanoclusters

In this industrial era, the use of low-dimensional nanomaterials as gas sensors for environmental monitoring has received enormous interest. To develop an effective sensing method for ethylene oxide (EO), DFT computations are conducted using method ωB97X-D and B3LYP with 6-31G(d,p) basis set to evaluate the adsorption behavior of ethylene oxide gas on the surfaces of pristine, as well as Scandium and Titanium decorated B12N12, Al12N12, and Al12P12 nanocages. Several properties like structural, physical, and electronic are studied methodically to better understand the sensing behavior. Scandium-decorated aluminum phosphate and boron nitride nanocages were shown to perform better in terms of adsorption properties. The short recovery time observed in this study is beneficial for the repetitive use of the gas sensor. The Natural Bond Orbital and molecular electrostatic potential analysis demonstrated a substantial quantity of charge transfer from adsorbate to adsorbents. The bandgap alternation after adsorption shows an influence of adsorption on electronic properties. The interactions of adsorbate and adsorbents are further studied using the ultraviolet–visible predicted spectrum, and quantum theory of atoms in molecules all of which yielded promising findings.

Preferential Adsorption of Ethylene Oxide on Fe and Chlorine on Ni Enabled Scalable Electrosynthesis of Ethylene Chlorohydrin

AbstractIndustrial manufacturing of ethylene chlorohydrin (ECH) critically requires excess corrosive hydrochloric acid or hypochlorous acid with dealing with massive by‐products and wastes. Here we report a green and efficient electrosynthesis of ECH from ethylene oxide (EO) with NaCl over a NiFe2O4nanosheet anode. Theoretical results suggest that EO and Cl preferentially adsorb on Fe and Ni sites, respectively, collaboratively promoting the ECH synthesis. A Cl radical‐mediated ring‐opening process is proposed and confirmed, and the key Cl and carbon radical species are identified by high‐resolution mass spectrometry. This strategy can enable scalable electrosynthesis of 185.1 mmol of ECH in 1 h with 92.5 % yield at a 55 mA cm−2current density. Furthermore, a series of other chloro‐ and bromoethanols with good to high yields and paired synthesis of ECH and 4‐amino‐3,6‐dichloropyridine‐2‐carboxylicacid via respectively loading and unloading Cl are achieved, showing the promising potential of this strategy.

Preferential Adsorption of Ethylene Oxide on Fe and Chlorine on Ni Enabled Scalable Electrosynthesis of Ethylene Chlorohydrin.

Industrial manufacturing of ethylene chlorohydrin (ECH) critically requires excess corrosive hydrochloric acid or hypochlorous acid with dealing with massive by-products and wastes. Here we report a green and efficient electrosynthesis of ECH from ethylene oxide (EO) with NaCl over a NiFe2 O4 nanosheet anode. Theoretical results suggest that EO and Cl preferentially adsorb on Fe and Ni sites, respectively, collaboratively promoting the ECH synthesis. A Cl radical-mediated ring-opening process is proposed and confirmed, and the key Cl and carbon radical species are identified by high-resolution mass spectrometry. This strategy can enable scalable electrosynthesis of 185.1 mmol of ECH in 1 h with 92.5 % yield at a 55 mA cm-2 current density. Furthermore, a series of other chloro- and bromoethanols with good to high yields and paired synthesis of ECH and 4-amino-3,6-dichloropyridine-2-carboxylicacid via respectively loading and unloading Cl are achieved, showing the promising potential of this strategy.

First-Principles Studies of Ethylene Oxide Adsorption on Pristine and Doped Graphenes

First-Principles Studies of Ethylene Oxide Adsorption on Pristine and Doped Graphenes

Adsorption of ethylene oxide on doped monolayers of MoS2: A DFT study

Density functional theory (DFT) calculations have been performed to investigate the doping of Ti, Ni, Pd, Si, Ge, P, and Cl atoms into an S-vacancy of MoS2 monolayer, and its impact on the sensitivity toward ethylene oxide (EO). The results show that, pristine MoS2 is chemically inert toward EO, however, Ti, Ni, Pd, and Si doping facilitates a stronger binding with the molecule, and an enhanced charge transfer sufficient for detection. Furthermore, the electronic band gap of Ti, and Si doped MoS2 is shown sensitive toward EO, experiencing a 0.26 eV (22%) and 0.85 eV (51%) change upon adsorption, which suggests a second mode of detection. The investigation also illustrates that, in order to achieve stronger binding and adsorption-sensitive band gap the d-block doped MoS2 requires a strong pz/dz2 hybridization, while p-block doped layer requires an activation of the s subshell of the dopant.

Effect of Er doping on flame-made SnO2 nanoparticles to ethylene oxide sensing

In this research, 0.05–2 wt% Erbium (Er)-doped SnO2 nanoparticles were synthesized for the first time by flame spray pyrolysis and their gas-sensing properties were methodically characterized. The structural analyses based on scanning/transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen sorption analysis, and photoluminescent spectroscopy suggested that nanocrystalline SnO2 nanoparticles were substitutionally doped with Er+3 species. The sensing films were prepared by powder pasting and spin-coating processes and their gas-sensing performances were evaluated in the temperature range of 200–400 °C under dry and humid air conditions. The test results reported that the optimum Er content of 0.1 wt% provided the optimally high and selective response of 347 to 30 ppm C2H4O with a short response time of ∼2 s and a low detection limit of 18 ppb, which were substantially better than those of undoped one at the best working temperature of 350 °C. The high selectivity was confirmed against CH2O, C3H6O, C2H5OH, NH3, C2H2, C2H4, H2, CH4, H2S, H2O and CO. Besides, the influence of humidity on C2H4O response of Er-doped SnO2 sensor was moderately low over a wide relatively humidity range of 0–80 %. The gas-sensing mechanisms were proposed with a new model describing the catalytic roles of p-type Er dopants to ethylene oxide adsorption.

Transition metals doped ZnO nanocluster for ethylene oxide detection: A DFT study

Abstract Density functional theory (DFT) studies at B3LYP/6-31G (d) (Becke, 3-parameter, Lee-Yang-Parr) level were performed to evaluate adsorption interactions between ethylene oxide (EO) molecule, and pristine and transition metals (TM) (i.e., Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) doped ZnO nanocluster (TM-doped Zn12O12). The adsorption energy (Ead), band gap energy (Eg), Mulliken charge transfer (QT) and molecular electrostatic potential (MEP) were calculated to examine the sensitivity of the Zn12O12 and its TM-doped forms toward EO detection. It was found that in contrast to the pristine Zn12O12, the electronic properties of TM-doped Zn12O12 were sharply sensitive to the presence of EO gas molecules. The results revealed that among the studied TM-doped Zn12O12, Cr- and V-doped Zn12O12 have great potential applicability as EO sensor, due to their highest Eg change (ΔEg) values, after the EO adsorption. Moreover, the density of state (DOS) calculations confirmed that strong electronic interaction between Cr- and V-doped Zn12O12 and EO molecules can makes them interesting empirical candidate for detection and adsorptive removal of EO gas molecules.

Effect of the Si, Al and B doping on the sensing behaviour of carbon nanotubes toward ethylene oxide: a computational study

ABSTRACTExo– and endo–adsorption of ethylene oxide (EO) on pristine (9,0) (zigzag) carbon nanotube (CNT) and its doped forms with silicon (Si–CNT), aluminum (Al–CNT) and boron (B–CNT) were investigated using density functional theory (DFT) at M06–2X/6–311++G** level. The natural bond orbital (NBO) and the quantum theory of atoms in molecules (QTAIM) analyses were also performed by using the same level of theory. The effect of the doping on sensing behaviour of the CNT toward EO molecule was investigated through intermolecular interactions studies by calculation of total and partial density of states (DOS, PDOS). The enhanced sensitivity of doped–CNTs towards EO molecule associated with adsorption energies (Eads) and the changes in geometric and electronic structures was examined and the global chemical reactivity parameters were calculated and comprehensively analysed. The thermodynamic property changes were calculated and compared. The results indicated that the EO adsorption on the pristine and doped CNTs was an exothermic spontaneous process. Moreover, based on the calculated Eg change (ΔEg) and Eads values, Al–CNT with superior sensitivity for sensing of EO molecule, indicates promising perspectives for its use in fabrication of new EO gas–sensing devices.

Effect of external electric field on the adsorption of ethylene oxide on pristine and Al-doped coronenes: A DFT study

The adsorption interactions between ethylene oxide (EO) molecule and pristine and aluminum-doped coronene (Al-coronene) were studied in the presence and absence of perpendicular external electric fields (EFs) with strengths [Formula: see text], [Formula: see text] and [Formula: see text] a.u. using density functional theory (DFT) calculations. The geometry optimizations and adsorption calculations were carried out by employing 6-31[Formula: see text]G** basis set. The changes in geometric and electronic structures after the adsorption were investigated to characterize the sensitivity of pristine and Al-coronene toward EO molecules. For all the studied systems, adsorption energies ([Formula: see text], band gap energy ([Formula: see text], Mulliken charge transfer, molecular electrostatic potential (MEP) and density of electron state (DOS) were calculated and discussed. According to the obtained results, the high impact of the applied EFs on the adsorption characteristics of EO molecules on the pristine and Al-doped coronenes showed that applying EF is a good strategy for enhancing the EO adsorption capability of the pristine and Al-doped coronenes, improving the potential application of coronene-based sensors for detection of EO in trace amounts.

Surface modification of contact lenses using adsorption of ethylene oxide branched copolymers

AbstractTo examine methods for reducing the amount of adsorbed protein on the surface of contact lenses during use, cationic copolymers containing poly(ethylene oxide) units were synthesized and evaluated as surface modifiers. Poly(ethylene oxide) graft‐branched copolymers of composition 70 mol % dimethylaminoethyl methacrylate (DM) and 30 mol % methoxy polyethylene glycol methacrylate (Mp0G; p = 2, 4, 9; the average number of the ethylene oxide units) were obtained using nonionic monomers containing poly(ethylene oxide) units. The copolymers very efficiently prevented protein adsorption on a contact lens. Contact angle measurements showed that immersion in tear fluid made the lens surface hydrophobic because of adsorption of proteins with hydrophobic residues. The copolymer pretreatment made the lens surface hydrophilic, even after dipping in artificial tear fluid. These results suggest that adsorption of the poly(ethylene oxide) branched copolymer on the contact lens would make the lens surface hydrophilic and prevent protein adsorption. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Studies of Ethylene Oxide Adsorption on Pt−Sn Alloys with TPD, HREELS, UPS, and DFT Calculations

Ethylene oxide (EO) adsorption was studied on two ordered surface alloys: (2 × 2)-Sn/Pt(111) with θSn = 0.25 ML, and (√3 × √3)R30°-Sn/Pt(111) with θSn = 0.33 ML. Nearly all EO desorbs molecularly d...

Comments on “Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces”

This letter is a re-examination of the ethylene oxide (EO) temperature programmed desorption (tpd) peak shapes (reported in references 1 and 2) which were obtained by tpd after having adsorbed EO at 250 K on to Ag(110) and Ag(111) surfaces. In these papers, the peaks were deemed to originate from a unimolecular rearrangement of an adsorbed oxametallacycle, producing EO, which desorbed on formation. Consequently, on the basis of this thesis, the activation energy of the composite process of internal rearrangement of the oxametallacycle and desorption of EO was determined by solution of the first order Redhead equation [3] at the peak maximum temperature, using an assumed value of 1013 s−1 for the desorption pre-exponential term. The conclusions of this re-examination are that the m/z = 29 desorption peaks shown in Fig. 1 derive from a second order surface reaction of an adsorbed O atom and adsorbed ethylene molecule and that this is the rate determining step in the desorption of EO. An important corollary of these conclusions is that an oxametallacycle is not involved in the ethylene epoxidation reaction coordinate as the papers suggest. Open image in new window Fig. 1 The m/z 29 desorption spectra following ethylene oxide adsorption at 250 K on Ag(110): ethylene oxide exposure—(a) 10L, (b) 5L, (c) 0.5L and (d) 0.1L

H−ZSM-5 for the Removal of Ethylene Oxide: Effects of Water on Filtration Performance

Zeolite H−ZSM-5 with a SiO2/Al2O3 ratio of 25 was evaluated for its ability to remove ethylene oxide (EtO) from streams of air at 25 °C and between 15 and 90% relative humidity (RH). The primary mechanism for the removal of ethylene oxide using H−ZSM-5 involves a catalyzed hydrolysis reaction initiated by the adsorption of EtO onto a Bronsted acid site. Secondary addition reactions leading to the formation of polyglycols are also occurring. The reaction is poisoned by the accumulation of reaction products within the pores of the zeolite, which ultimately leads to elution of EtO from the filter bed. The ability of H−ZSM-5 to remove EtO decreased significantly as the relative humidity increased from 50 to 90%. For example, the EtO breakthrough time decreases from 220 min at 50% RH to 57 min at 90% RH. The decrease in the EtO breakthrough time over the stated RH range is attributed to the increased hydration of the Bronsted acid site. As the extent of Bronsted acid site hydration increases, the reactivity of...

A comparative study of ethylene oxide and diethylene dioxide adsorption on silicon (0 0 1)

The adsorption of ethylene oxide (oxirane) and diethylene dioxide (1,4-dioxane) on the Si(0 0 1) surface was investigated using the first-principles pseudopotential method within a generalised gradient approximation to the density functional theory. Our results indicate that oxirane adsorption on the silicon surface probably occurs via C–C bond. This interaction induces the breaking of the C–C bond and the formation of a Si–C–O–C–Si ring. The 1,4-dioxane interaction with the silicon (2 × 2) surface, on the other hand, results in the decomposition of the considered molecule in different radicals, depending on the original adsorbed structure. In order to disregard the possible influence of the slab considered, we suggest that high order reconstruction surfaces, i.e. (4 × 2) or (4 × 4), should be investigated.

TPD and FT-IRAS Investigation of Ethylene Oxide (EtO) Adsorption on a Au(211) Stepped Surface

Adsorption of ethylene oxide, CH(2)CH(2)O (EtO), on a Au(211) stepped surface was studied by temperature programmed desorption (TPD) and Fourier transform infrared reflection-absorption spectroscopy (FT-IRAS). Ethylene oxide was completely reversibly adsorbed, and desorbed molecularly during TPD following adsorption on Au(211) at 85 K. EtO TPD peaks appeared at 115 K from the multilayer film and 140 and 170 K from the monolayer. Desorption at 140 K was attributed to EtO desorption from terrace sites, and that at 170 K to EtO desorption from step sites. Desorption activation energies and corresponding adsorption energies were estimated to be 8.4 and 10.3 kcal mol(-1), respectively. The EtO ring (C(2)O) deformation band appeared in IRAS at 865 cm(-1) for EtO in multilayer films and when adsorbed in the monolayer at terrace sites. The stronger chemisorption bonding of EtO at Au step sites slightly weakens the bonding within the molecule and causes a small red-shift of this band to 850 cm(-1) for adsorption at step sites. EtO presumably binds via the oxygen atom to the surface, and observation of the EtO-ring absorption band in IRAS establishes that the molecular ring plane of EtO adsorbed at step and terrace sites is nearly upright with respect to the crystal surface plane.

Ethylene epoxidation on Ag: identification of the crucial surface intermediate by experimental and theoretical investigation of its electronic structure.

Intermediate success: A combination of high-resolution X-ray photoelectron spectroscopy and density functional theory allows the electronic structures of adsorbates to be probed to an unprecedented level of detail. By using these techniques, the adsorption of ethylene oxide onto an Ag(111) surface has been shown to result in the formation of an unsymmetrical surface oxametallacycle structure (see picture).

TPD and HREELS reinvestigation of ethylene oxide adsorption on Pt()

Abstract A reinvestigation of ethylene oxide (EtO) adsorption and desorption on Pt(1 1 1) is reported using primarily TPD, AES, XPS and HREELS. EtO does not react when adsorbed on Pt(1 1 1) at 90 K and then subsequently heated under UHV conditions. Specifically, TPD results and AES measurements taken after TPD experiments place an upper limit on the extent of EtO decomposition at 0.02 ML. This work helps to correct earlier work that showed significant decomposition on this surface. HREELS identified molecular EtO adsorption at 90 K, with only small shifts in molecular vibrational frequencies from condensed phase spectra. At a coverage of less than 0.1-ML EtO, EtO is bonded oxygen-end down to the Pt(1 1 1) surface with C 2v symmetry, i.e., with the C 2 axis of EtO normal to the surface. By showing that the close-packed Pt(1 1 1) surface is less reactive toward the desired product of ethylene epoxidation than previously thought, these new results should be helpful in discussing differences between the chemistry of Ag and Pt catalysts for this reaction.

Hydrotalcite-type catalysts for narrow-range oxyethylation of 1-dodecanol using ethyleneoxide

Hydrotalcite-type catalysts were studied for the oxyethylation of 1-dodecanol. Hydrotalcite-type catalysts treated with dodecanoic acid are very active for the narrow-range oxyethylation of 1-dodecanol. The narrow distribution of oxyethylene units in the dodecylethoxylates is elucidated by the constrained reaction on the surface of hydrotalcite-type catalysts. In the proposed surface reaction scheme, the following points are presented. (1) The relatively basic reactants, ethylene oxide and dodecylalcohol or dodecylethoxylates, are adsorbed on the relatively acidic Al 3+ sites of the surface. (2) The adsorption of ethylene oxide is increasingly interfered with due to the occupation of dodecylethoxylates of higher number of oxyethylene units on the isolated acidic sites of the catalyst. (3) The interference results in the decrease of oxyethylation rate in each additional ethylene oxide insertion step, due to a smaller number of the ethylene oxide molecules adsorbed near the growing point of alcohol ethoxylates. (4) The difference in ethylene oxide insertion rates with the numbers of oxyethylene units in the dodecylethoxylate products causes peaking of the distribution. The large difference of oxyethylation activity over hydrotalcite-type catalysts of distinct Mg and Al composition ratios may be correlated with the numbers of Al 3+ sites at the closest distance from an Al 3+ site, which can be deduced from the ideal hexagonal or orthorhombic super lattice of Al 3+ sites on the hydrotalcite surface layer.

Linking atomistic and mesoscale simulations of water-soluble polymers.

A link between molecular and mesoscopic simulations for water-soluble polymers is made using the potential of mean force (PMF) method. Mesoscale parameters are adjusted to match selected thermodynamic quantities such as the monomer second virial coefficient or the limiting slope of the monomer adsorption isotherm, which are computed directly from atomistic PMFs. The method is illustrated by computing the bulk and surface interaction parameters (chi parameters in self-consistent field theory) for the adsorption of ethylene oxide (EO) and propylene oxide (PO) polymers from aqueous solution onto silica.

Examination of the adsorption of ethylene oxide–propylene oxide triblock copolymers to soil

The adsorption of 5 surfactants (P103, P105, F108, F127 and L92) to a sandy soil has been investigated. The surfactants are ABA block copolymers in which the A blocks are synthesised from ethylene oxide and the B block from propylene oxide. CMC values, for the block copolymers, as well as surfactant sorption to soil were measured by surface tension techniques. The adsorption of all five compounds can be described by the Freundlich adsorption isotherm. Adsorption, in each case, is related to the critical micelle concentration of the surfactant and the extent of adsorption appears to be linked also to the fraction of soil organic matter.