Advanced oxidation of aromatic VOCs using a pilot system with electron beam–catalyst coupling

The decomposition of volatile organic compounds (VOCs) using a pilot system of electron beam (EB)–catalyst coupling was investigated. Two aromatic VOCs, toluene (1800 ppmC) and o-xylene (1500 ppmC), were irradiated with a dose range of 0–10 kGy at room temperature. The removal efficiencies for toluene and o-xylene were 92.4% and 94.5%, respectively, under a 10 kGy absorbed dose condition, which were higher than the results of 45.7% and 52.3% when EB-only was used, respectively. The CO₂ selectivity approached 100% for both toluene and o-xylene using the EB-catalyst coupling system, while the concentrations of O₃ formed were 0.02 ppm (toluene) and 0.003 ppm (o-xylene) at 10 kGy. The aerosol concentration was also measured as 43.2 μg/m³ (toluene) and 53.4 μg/m³ (o-xylene) at 10 kGy absorbed dose.     

Combined radiolytic and catalytic oxidizing method to remove toluene in gas phase

We enhanced the decomposition and the removal of toluene in gas phase using a combined method that consists of electron beam (EB) irradiation and catalytic oxidation. The catalytic oxidation system comprises oxidizing particles of 0.1 wt% Pt or 0.1 wt% Pd deposited to supporting materials, which were also used as adsorbents. These adsorbents—supporting materials are Cordierite, Y-zeolite, and γ-alumina. We demonstrated that 100% removal of toluene can be achieved using approximately 9 kGy of dose level in the presence of Pt or Pd deposited to 12 wt%. The G (-toluene) values were determined to be 0.498 and 0.829 μmol/J in the absence and presence of these catalysts with adsorbents, respectively. We have also demonstrated that the presence of the oxidation-catalyst prevents the toluene from undergoing radiolytic polymerization.     

Al-centered functionalized inorganic–organic hybrid sorbent containing N and S donor atoms for effective removal of cadmium

A new aluminium-incorporated layered inorganic–organic hybrid material (Al-GPTS-TU) has been successfully synthesized by using sol–gel based precursor under mild temperature condition and silylaing agent (GPTS-TU) derived from the reaction of 3-glycidoxypropyltrimethoxysilane (GPTS) and thiourea (TU). The hybrid material was characterized by using various instrumentation techniques and the result confirmed the attachment of organic functionality to the inorganic silicon network. The inter-lamellar distance for the hybrid material was found to be 41.33 Å. The synthesized hybrid was used for the removal of cadmium from dilute aqueous solution with variation of solution parameters. Thermodynamic parameters ΔH and ΔS, evaluated for the adsorption of cadmium from water solution, were found to be 73.68 kJ mol^?1 and 282.9 J mol^?1 K^?1, respectively, indicating adsorption process to be endothermic in nature. The negative value of ΔG indicated the feasibility and spontaneity of ongoing adsorption process. The hybrid material containing multiple coordination sites such as S and N in the attached organic functionality can find potential applications for the removal of various metal toxicants from water bodies to prevent the eco-system.     

Novel hybrid technology for VOC control using an electron beam and catalyst

Noble (Pt, Pd) and transition metals (Mn, Cu) were employed as coupling catalysts to evaluate the toluene (1500 ppm C of initial concentration) removal efficiencies in the electron beam (EB)-catalyst coupling system. The toluene removal efficiency was 60.1% in the EB-only system at a dose of 8.7 kGy. In the presence of the metal catalysts (Pt, Pd, Cu and Mn), the removal efficiency was enhanced by 37, 33, 6 and 22%, respectively, compared to that of EB-only treatment. It was found that the selectivity to CO₂ with Pt and Pd coupling were relatively higher than those of Cu and Mn. Especially the CO₂ selectivity of EB-Pt coupling was significantly high at a relatively low absorbed dose. The removal efficiencies were compared for loading of catalyst and there was no significant difference among 0.1, 0.5 and 1.0 wt%.     

Pyrolysis of waste tyres: The influence of USY catalyst/tyre ratio on products

In this paper, an ultrastable Y-type (USY) zeolite was investigated with two-staged pyrolysis–catalysis of waste tyres. Waste tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a secondary catalytic reactor. The main objective of this paper was to obtain high concentration of certain aromatic hydrocarbons suitable to be used as a chemical feedstock rather than a liquid fuel, and the influence of catalyst/tyre ratio on the product yield and composition of derived oils. The light fraction (boiling point < 220 °C) was distilled from the derived oil prior to be analyzed with gas chromatography/mass spectrometry (GC/MS). It showed that the increase of catalyst/tyre ratio resulted in high yield of gas at the expense of the oil yield. The high catalyst/tyre ratio favored to increase the concentration of light fraction (<220 °C) in oil. Increasing the catalyst/tyre ratio resulted in significant changed in the concentration of benzene, toluene, xylenes and the alkyl aromatic compounds. For benzene and toluene, the highest concentration was obtained at the catalyst/tyre ratio of 0.5. The concentration of xylenes increased with the increasing of catalyst/tyre ratio.     

Excess volumes of binary mixtures of vinyl acetate and aromatic hydrocarbons

Excess molar volumes of (vinyl acetate  +  toluene, or ethylbenzene, orp -xylene, or isopropylbenzene, or butylbenzene, or isobutylbenzene, or mesitylene, or t -butylbenzene), were determined from density measurements at T =  298.15 K using a vibrating-tube densimeter. The excess molar volumes are positive over the whole composition range, and increase with the size of the hydrocarbon. Steric hindrance in these mixtures was investigated in terms of the partial excess molar volumes behaviour. The experimental data were used to determine the binary interaction parameters of the Soave–Redlich–Kwong (SRK) equation of state for use in multicomponent excess functions calculations.     

Experimental densities,refractive indices,and speeds of sound of 12 binary mixtures containing alkanes and aromatic compounds at T = 313.15 K

Densities, speeds of sound, and refractive indices of 12 binary systems of alkanes (hexane, heptane, octane, and nonane) with aromatics (benzene, or toluene, or ethylbenzene) at T = 313.15 K and at atmospheric pressure were determined over the whole composition range, and are presented in this paper. From the experimental results, the derived and excess properties (isentropic compressibility, excess molar volumes, and excess molar isentropic compressibility) at T = 313.15 K were calculated and satisfactorily fitted to the Redlich–Kister equation.     

Catalytic asymmetric hydrosilylation of acetophenone with new chiral thiourea ligands containing the (S)-α-phenylethyl group

New chiral thioureas 1–8 containing 1,2-ethylendiamine or trans-1,2-diaminocyclohexane as the carbon skeleton, and containing an (S)-α-phenylethyl group have been prepared (79–98% yield). Thioureas 1–8 were used as ligands for the zinc-based catalyzed asymmetric hydrosilylation of acetophenone with polymethylhydrosiloxane (PMHS). The best result was achieved with monothiourea 1 (up to 75% ee), in toluene and a catalyst load of 5 mol %.     

Radiolysis of phenol in aqueous solution at elevated temperatures

γ-Radiolysis and pulse radiolysis of phenol in aqueous solution up to supercritical condition have been carried out. G-values of phenol consumption and product formation have been determined. While dihydroxybenzenes were major products at room temperature, multi-ring compounds and benzene were formed above 300 °C. This indicates reaction mechanism was changed above 300 °C, where phenoxyl radical plays a predominant role. This is supported by the observation of phenoxyl radical in pulse radiolysis. In supercritical water, the G-values increased with decrease of density.     

Iodine-catalyzed,one-pot,three-component aza-Friedel–Crafts reaction of electron-rich arenes with aldehyde/carbamate combinations

Iodine is shown to be an efficient catalyst for a one-step, three-component aza-Friedel–Crafts reaction of activated arenes or heteroarenes with benzyl or tert-butyl carbamates in combination with a wide variety of aldehydes in toluene under ‘open-flask’ and mild conditions. In the presence of 5 mol % of iodine in toluene at room temperature, the reaction gives the corresponding N-CBz or N-Boc protected α-branched amines, selectively, in good to excellent yields.     

Advanced oxidation process by electron-beam-irradiation-induced decomposition of pollutants in industrial effluents

Electron-beam irradiation considered on advanced oxidation process induces the decomposition of pollutants in industrial effluent. Experiments were conducted using a radiation dynamics electron beam accelerator with 1.5 MeV energy and 37 kW power. The effluent samples from an industrial complex were irradiated using the IPEN's liquid effluent irradiation pilot plant. The experiments were conducted using one sample from each of eight separate industrial units and five samples of a mixture of these units. The physical–chemical characterization of these samples is presented. The electron beam irradiation was efficient in destroying the organic compounds delivered in these effluents, mainly, chloroform, dichloroethane, methyl isobutyl ketone, toluene, xylene and phenol. The necessary dose to remove 90% of the most organic compounds from industry effluent was 20 kGy. The removal of organic compounds from this complex mixture was explained by the destruction G value (Gd) that was obtained for those compounds with different initial concentrations and was compared with literature.     

Densities,excess molar volumes,and refractive indices of ethyl acetate and aromatic hydrocarbon binary mixtures

Densities, excess molar volumes, refractive indices, and changes in refractive index on mixing for (ethyl acetate  +  benzene, or methylbenzene, or ethylbenzene, or 1-4-dimethylbenzene, or 1-methylethylbenzene, or 1-3-5-trimethylbenzene, or 1-1-dimethylethylbenzene) have been determined atT =  298.15 K. The excess molar volumes and changes in refractive index have been fitted to Redlich–Kister polynomials. The π -electrons interactions of the benzene ring and the peculiar plate shape of the aromatic molecules are noticeably modified by the presence of the ethyl acetate molecules of a different nature. The intermolecular interactions are strongly modified and result in positive excess volumes except for toluene or p -xylene whose values are close to zero. The refractive indices were compared with calculated values using mixing rules proposed by several authors.     

About the OH yield in the radiolysis of an aqueous/H2O2 system. Its optimisation for water treatment

Unless the radiolytic reducing species are neutralised or converted into oxidising species, an EB remediation system cannot be considered a true Advanced Oxidation Processes (AOP). A water/H₂O₂ system irradiated by UVC mercury lamps constitutes a widely used OH production method. Employing H₂O₂ in radiolysis as well, an enhancement of the oxidative efficiency of an EB treatment can be obtained. Pulse radiolysis measurements of an aerated aqueous/H₂O₂/KSCN system have been systematically undertaken to assess the optimal H₂O₂ concentration. By linearly fitting a competition kinetics relationship, it is found that the scavengeable extra-yield of OH is ΔG(OH)=0.24 μmol J^?1 (R=0,9958), while the maximum experimental yield is measured G(OH)_max=(0.52±0.02) μmol J^?1 when [H₂O₂]=5–10 mM. Exceeding these concentrations the OH yield drops off.     

Catalytic fast pyrolysis of jatropha wastes

In this work, the decomposition behaviors of jatropha wastes (husk, seed shell and branch) have been examined in order to get desired liquid organic compounds, but not undesired inorganic compounds such as CO, CO₂, water and coke. The jatropha wastes exhibit a stepwise degradation pathway which has a slight difference in between samples before and after milling. In the preliminary pyrolysis using quartz reactor and H-ZSM-5(30) catalyst, the liquid products selectivity was seed shell > blanch > husk > seed shell (no catalyst). In the absence of catalyst, the Py-GC/MS analyses for pyrolysis of jatropha wastes show a range of aromatic hydrocarbons, phenols, alcohols and ketones, acids and esters, ethers and aldehydes. Aromatics are predominantly formed above 90% of area percentage by use of catalyst. Of aromatic compounds, xylenes, naphthalenes and toluene are mainly produced. The product selectivity is dependent on both the size of the catalyst pores and the nature of the active sites and one candidate is H-ZSM-5 and the other candidate is β-zeolite. The reaction pathway involves dehydrogenation and dehydroaromatization of aliphatic oxygenates such as alkylcyclohexanol and higher carboxylic acids to form phenol derivatives, which undergo hydrodeoxygenation into toluene and xylenes, followed by dehydroaromatization to give naphthalenes.     

DFT study of group 8 catalysts for the hydrophenylation of ethylene: Influence of ancillary ligands and metal identity

Computational methods are used to investigate catalytic hydrophenylation of ethylene using complexes of the type [(Y)M(L)(CH₃)(NCMe)]ⁿ⁺ [Y = Mp, n = 1; Y = Tp, n = 0; M = Ru or Os; L = PMe₃, PF₃, or CO; Mp = tris(pyrazolyl)methane; Tp = hydrido-tris(pyrazolyl)borate]. The conversion of ethylene and benzene to ethylbenzene with [(Y)M(L)(Ph)]ⁿ⁺ as catalyst involves four steps: (1) ethylene coordination, (2) ethylene insertion into the M–Ph bond, (3) benzene coordination, and (4) benzene C–H activation. DFT calculations form the basis to compare stoichiometric benzene C–H activation by [(Y)M(L)(CH₃)(NCMe)]ⁿ⁺ complexes to yield methane and [(Y)M(L)(Ph)(NCMe)]ⁿ⁺. In addition, starting from the 16-electron species [(Y)M(L)(Ph)]ⁿ⁺, potential energy surfaces for the formation of ethylbenzene are calculated to reveal the impact of modifications to the scorpionate ligand (Mp or Tp), co-ligand (L) and metal center (M).     

Excess enthalpies for mixtures of acrylonitrile and an aromatic hydrocarbon at T = 298.15 K and p = 101325 Pa

Excess molar enthalpies for (acrylonitrile  +  benzene, or methylbenzene, or 1,2-dimethylbenzene, or 1,3-dimethylbenzene, or 1,4-dimethylbenzene, or 1,3,5-trimethylbenzene, or ethylbenzene) atT =  298.15 K and p =  101325 Pa are presented. The excess molar enthalpy range from 531J · mol ^− 1at x =  0.5 for 1,3,5-trimethylbenzene to 210J · mol ^− 1at x =  0.5 for toluene. The Redlich–Kister equation, the NRTL and UNIQUAC models were used to correlate the data.     

Thermodynamics of fuels with a bio-synthetic component (IV): (Vapor + liquid) equilibrium data for the ternary mixture (ethyl 1,1-dimethylethyl ether + 1-hexene + toluene) at T = 313.15 K

The paper reports experimental p–x data for the ternary system (ethyl 1,1-dimethylethyl ether + 1-hexene + toluene) at T = 313.15 K. The ether, synthesized from ethanol of biological origin, increases the interest of this compound as an additive for gasolines. An isothermal total pressure cell was used for the measurements. Data reduction by Barker’s method provides correlations for G^E, using Wilson, NRTL, UNIQUAC models and the Wohl expansion for the ternary system and the calculation of the vapor phase composition. Good results are obtained for the correlation by all the models.     

The use of ESR technique for assessment of heating temperatures of archaeological lentil samples

Heat-induced paramagnetic centers in modern and archaeological lentils (Lens culinaris, Medik.) were studied by X-band (9.3 GHz) electron spin resonance (ESR) technique. The modern red lentil samples were heated in an electrical furnace at increasing temperatures in the range 70–500 °C. The ESR spectral parameters (the intensity, g-value and peak-to-peak line width) of the heat-induced organic radicals were investigated for modern red lentil (Lens culinaris, Medik.) samples. The obtained ESR spectra indicate that the relative number of heat-induced paramagnetic species and peak-to-peak line widths depends on the temperature and heating time of the modern lentil. The g-values also depend on the heating temperature but not heating time. Heated modern red lentils produced a range of organic radicals with g-values from g = 2.0062 to 2.0035. ESR signals of carbonised archaeological lentil samples from two archaeological deposits of the Van province in Turkey were studied and g-values, peak-to-peak line widths, intensities and elemental compositions were compared with those obtained for modern samples in order to assess at which temperature these archaeological lentils were heated in prehistoric sites. The maximum temperatures of the previous heating of carbonised UA5 and Y11 lentil seeds are as follows about 500 °C and above 500 °C, respectively.     

(Liquid + liquid) phase behavior for systems containing (aromatic + TBA + methylcyclohexane)

The determination region of solubility of TBA (tert-butanol) with representative compounds of the gasoline was investigated experimentally at temperature of 298.2 K. Type 1 (liquid + liquid) phase diagrams were obtained for (methylcyclohexane + TBA + aromatic compounds). These results were correlated simultaneously by the UNIQUAC model. The values of the interaction parameters between each pair of components in the systems were obtained for the UNIQUAC model using the experimental result. The root mean square deviation (RMSD) between the observed and calculated mole percents was 1.88 for (methylcyclohexane + TBA + benzene), 2.45 for (methylcyclohexane + TBA + toluene) and 2.86 for (methylcyclohexane + TBA + ethylbenzene). The mutual solubility of methylcyclohexane and aromatic compounds (e.g., benzene toluene and ethylbenzene (BTE)) was also investigated by the addition of TBA at temperature of 298.2 K.     

Polycyclic aromatic hydrocarbons in coal combustion flue gas under electron beam irradiation

The electron beam (EB) technology has been investigated as a one-stage multi-component purification technology. The initial concentrations of SO₂, NO_x, and 16 polycyclic aromatic hydrocarbons (PAH) in flue gas have been reduced simultaneously by over 60%, 50%, and 20%, respectively, in flue gas at the dose of 8 kGy. Determined PAH distribution in the by-product has shown negligible role of adsorption in PAH removal. PAH-based overall toxicity of flue gas decreased remarkably in the range of 30–80% under EB irradiation.