Papers by Romeo-Iulian Olariu
. The Environmental Simulation Chamber made of Quartz from the University “Alexandru Ioan Cuza” f... more . The Environmental Simulation Chamber made of Quartz from the University “Alexandru Ioan Cuza” from Iasi (ESC-Q-UAIC), Romania, was used to investigate for the first time the gas-phase reaction rate coefficients for four nitrocatechols towards OH radicals under simulated atmospheric conditions. Employing relative rate technique at a temperature of 298 ± 2 K and total air pressure of 1 atm, the obtained rate coefficients (in 10−12 cm3×s−1) were as followed: k3NCAT = (3.41 ± 0.37) for 3-nitrocatechol, k4NCAT = (1.27 ± 0.19) for 4-nitrocatechol, k5M3NCAT = (5.55 ± 0.45) for 5-methyl-3-nitrocatechol and k4M5NCAT = (0.92 ± 0.14) for 4-methyl-5-nitrocatechol. For the investigated compounds the photolysis rates in the actinic region, scaled to atmospheric relevant conditions, were evaluated as well. In this case the photolysis rate coefficient values were obtained only for 3-nitrocatechol and 5-methyl-3-nitrocatechol: J3NCAT = (3.06 ± 0.16) × 10−4 s−1 and J5M3NCAT = (2.14 ± 0.18) × 10−4 s−1, respectively. Considering the obtained results our study suggests that photolysis may be the main degradation process for 3-nitrocatechol and 5-methyl-3-nitrocatechol in the atmosphere. Results are discussed in terms of the reactivity of the investigated four nitrocatechols towards OH-radical initiated oxidation and their structural features. The rate coefficient values are also compared with those estimated from the structure-activity relationship for monocyclic aromatic hydrocarbons. Additional comparison with similar compounds is also presented underlining the implications towards possible degradation pathways and atmospheric behavior.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Water
The Podu Iloaiei Dam Lake located on the Bahluet River from Bahlui hydrographic basin, north-east... more The Podu Iloaiei Dam Lake located on the Bahluet River from Bahlui hydrographic basin, north-eastern Romania, is one of the most important water resources used for aquaculture activities in the region of interest. In the present study, the chemical composition related to water-soluble ions and elements was assessed in both water and sediment samples collected from the area of interest during July 2017 and October 2017, representative months for warm and cold seasons, respectively. Water-soluble ions (H3C2O2−, HCO2−, C2O42−, F−, Cl−, NO2−, Br−, NO3−, SO42−, Li+, Na+, NH4+, K+, and Ca2+) were analyzed by ion chromatography, while inductively coupled plasma mass spectrometry was used to quantify water-soluble fractions of elements (Be, B, Mg, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Mo, Ru, Pd, Ag, Cd, Sn, Sb, Te, Ba, Ir, Tl, Pb, Bi, and U). Evidence was obtained on the contributions of both anthropogenic and natural (pedologic) related sources in controlling the chemical...
Atmosphere
Nitrophenols are important products of the aromatic compounds photooxidation and play a considera... more Nitrophenols are important products of the aromatic compounds photooxidation and play a considerable role in urban chemistry. Nitrophenols are important components of agricultural biomass burning that could influence the climate. The formation of secondary organic aerosol from the direct photolysis of nitrophenols was investigated for the first time in a quartz glass simulation chamber under simulated solar radiation. The results from these experiments indicate rapid SOA formation. The proposed mechanism for the gas-phase degradation of nitrophenols through photolysis shows the formation of biradicals that could react further in the presence of oxygen to form low volatile highly oxygenated compounds responsible for secondary organic aerosol formation. The inhibiting effect of NOx and the presence of an OH radical scavenger on the aerosol formation were also studied. For 2-nitrophenol, significant aerosol formation yields were observed in the absence of an OH radical scavenger and NO...
Atmosphere
The reactions of five structurally similar unsaturated alcohols, i.e., (Z)-2-penten-1-ol, (E)-2-h... more The reactions of five structurally similar unsaturated alcohols, i.e., (Z)-2-penten-1-ol, (E)-2-hexen-1-ol, (E)-3-hexen-1-ol, (Z)-3-hexen-1-ol, and 1-octen-3-ol, with Cl atoms in the gas phase, were investigated at 296 ± 2 K and 1 atm by the relative-rate kinetic technique using a 600-L Teflon reaction chamber. Selected ion flow tube mass spectrometry (SIFT-MS) was used simultaneously to monitor the decay of the alcohols of interest and selected reference compounds. Tetrahydrofuran (THF), propan-1-ol, and octane were used as reference compounds. Chlorine atoms were produced by the photolysis of molecular chlorine (Cl2) using broadband actinic lamps near 365 nm. The estimated rate constant values (in 10−10 cm3∙molecule−1∙s−1) followed the order 2.99 ± 0.53 ((Z)-2-penten-1-ol) < 3.05 ± 0.59 ((E)-3-hexen-1-ol) < 3.15 ± 0.58 ((Z)-3-hexen-1-ol) < 3.41 ± 0.65 ((E)-2-hexen-1-ol) < 4.03 ± 0.77 (1-octen-3-ol). The present work provides the first value of the rate constant for the...
Revista de Chimie
New isopolyoxomolybdates and isopolyoxotungstates with both UO22+ and Th4+ ions have been synthes... more New isopolyoxomolybdates and isopolyoxotungstates with both UO22+ and Th4+ ions have been synthesized by self-assembly from raw materials as Na2MoO4�2H2O, Na2WO4�2H2O, uranyl acetate and thorium nitrate in acidic media under controlled conditions of temperature and pH. Accomplishments for the chemical characterization of the newly synthesized units is foreseen through the data obtained by the mean of state of art technique as Fourier Transformed Infrared Spectroscopy (FTIR), UV-vis spectrophotometry, scanning electronic microscopy (SEM) with electron diffraction X-ray (EDX) detection, and thermogravimetric analysis.
Revista de Chimie
Active pharmaceutical ingredients such as isoniazid, pyrazinamide and rifampicin are among the mo... more Active pharmaceutical ingredients such as isoniazid, pyrazinamide and rifampicin are among the most important first-line anti-tuberculosis drugs. A simple, rapid and sensitive reversed phase-high performance liquid chromatographic assay method for the simultaneous determination of isoniazid, pyrazinamide and rifampicin has been developed. Separation of the interest compounds was achieved in a 10 min chromatographic run in gradient elution mode on a Zorbax SB-C18 stainless steel column (150 � 4 mm, 5 mm) using a guard column containing the same stationary phase. The gradient elution was carried out with a mobile phase of 10% CH3CN aqueous solution for channel A and 50% CH3CN in pH = 6.8 phosphate buffer (20 mM), to which 1.5 mL triethylamine were added for channel B. Quantification of the analyzed substances was carried out spectrophotometrically at 269 nm. Detection limits of 0.48 mg/L for isoniazid, 0.52 mg/L for pyrazinamide and 0.48 mg/L for rifampicin were established for the de...
Revista de Chimie
The present work highlights the results of optical and electronic microscopy analyses performed o... more The present work highlights the results of optical and electronic microscopy analyses performed on fifteen selected outdated 20th century Romanian coins. The obtained results brought significant contributions in establishing specific archaeometric characteristics of corrosion coins products generated within the in-use and demonetization periods, under the action of both natural and anthropogenic factors. The work was mainly aimed in identifying the nature of the alloy and of the raw material used during coins minting, with specific emphasize on their resistance toward the action of various natural and anthropogenic factors. Emphasize is also given to the manufacturing techniques, edition characteristics and the in-use-interval. Performed elemental chemical analysis clearly showed that major elements abundances are highly correlated with coins origin area and their minting period.
This study assesses the atmospheric aerosol load and behaviour (size and seasonal dependent) of t... more This study assesses the atmospheric aerosol load and behaviour (size and seasonal dependent) of the major inorganic and organic aerosol ionic components (i.e., acetate, (C 2 H 3 O 2-), formate, (HCO 2-), fluoride, (F-), chloride, (Cl-), nitrite, (NO 2-), nitrate, (NO 3-), phosphate, (PO 4 3-), sulfate, (SO 4 2-), oxalate, (C 2 O 4 2-), sodium, (Na +), potassium, (K +), ammonium, (NH 4 +), magnesium, (Mg 2+) and calcium (Ca 2+), in Iasi urban area, northeastern Romania. Continuous measurements were carried out over 2016 by means of a cascade Dekati Low-Pressure Impactor (DLPI) performing aerosol size classification in 13 specific fractions evenly distributed over the 0.0276 up to 9.94 µm size range. Fine particulate Cl-, NO 3-, NH 4 + and K + exhibited clear minima during the warm seasons and clear maxima over the cold seasons, mainly controlled by corroboration between factors such as enhancement in the emission sources, changes in the mixed layer depth and specific meteorological conditions. Fine particulate SO 4 2did not show much variation with respect to seasons. Particulate NH 4 + and NO 3ions were identified as critical parameters controlling aerosols chemistry in the area. The measured concentrations of particulate NH 4 + and NO 3in fine mode (PM 2.5) aerosols were found to be in reasonable good agreement with modelled values for winter but not for summer, an observation reflecting actually the susceptibility of NH 4 NO 3 aerosols to be lost due to volatility over the warm seasons. Clear evidences have been obtained for the fact that in Iasi, northeastern Romania, NH 4 + in PM 2.5 is primarily associated with SO 4 2and NO 3but not with Cl-. However, indirect ISORROPIA-II estimations showed that the atmosphere in the investigated area might be ammonia-rich during both the cold and warm seasons, such as enough NH 3 to be present to neutralize H 2 SO 4 , HNO 3 and HCl acidic components and to generate fine particulate ammonium salts, in the form of (NH 4) 2 SO 4 , NH 4 NO 3 and NH 4 Cl. ISORROPIA-II runs allowed us estimating that over the warm seasons ~ 35 % of the total analyzed samples presented pH values in the very strong acidity fraction (0-3 Atmos. Chem. Phys. Discuss.,
Environmental Engineering and Management Journal
The paper proposes a statistical treatment to establish whether or not the level of the heavy met... more The paper proposes a statistical treatment to establish whether or not the level of the heavy metals contents found by FAAS on different mushroom species depend on the substratum type and on the growing-place (sampling area). Two different statistical procedures have been used: one-way ANOVA test and second PCA analyses. The results obtained by using both statistical procedures are in good agreement. From the one-way ANOVA analyses it has been concluded that Fe and Cu are independents while all other identified heavy metals (Mn, Co and Zn) are depending on the substratum type (mushroom species). The PCA procedure applied suggested that all FAAS data analysed can be organized using only two factors, namely F1 that contains significant contributions from Co, Zn, Mn, and factor F2 which contains less significant contributions from Cu, Fe.
Science of The Total Environment
Acta Chimica Slovenica
Recently, there is growing attention on the use of low-cost sorbents in the depollution of contam... more Recently, there is growing attention on the use of low-cost sorbents in the depollution of contaminated waters. As a consequence, the present work investigates the potential of soy bran and mustard husk as possible sorbent for the removal of arsenic(V) from residual water. Effects of various operating parameters such as: contact time, pH, initial arsenic concentration, pH, sorbent dose, temperature were investigated to determine the removal efficiency of arsenic(V). Thermodynamic parameters that characterize the process indicated that the adsorption is spontaneous and endothermic. The values for the separation factor, R L were less than one which confirms that the adsorption process was favorable. Equilibrium data fitted well to the Langmuir model with a higher adsorption capacity of soy bran (74.07 mg g-1) towards arsenic(V) ions than mustard husk (65.79 mg g-1). It was found that the pseudo-second order kinetic model was the best applicable model to describe the adsorption kinetic data.
Atmospheric Chemistry and Physics
This study assesses the effects of particle size and season on the content of the major inorganic... more This study assesses the effects of particle size and season on the content of the major inorganic and organic aerosol ionic components in the Iasi urban area, northeastern Romania. Continuous measurements were carried out over 2016 using a cascade Dekati low-pressure impactor (DLPI) performing aerosol size classification in 13 specific fractions over the 0.0276-9.94 µm size range. Fine-particulate Cl − , NO − 3 , NH + 4 , and K + exhibited clear minima during the warm season and clear maxima over the cold season, mainly due to trends in emission sources, changes in the mixing layer depth and specific meteorological conditions. Fine-particulate SO 2− 4 did not show much variation with respect to seasons. Particulate NH + 4 and NO − 3 ions were identified as critical parameters controlling aerosol chemistry in the area, and their measured concentrations in fine-mode (PM 2.5) aerosols were found to be in reasonable good agreement with modelled values for winter but not for summer. The likely reason is that NH 4 NO 3 aerosols are lost due to volatility over the warm season. We found that NH + 4 in PM 2.5 is primarily associated with SO 2− 4 and NO − 3 but not with Cl −. Actually, indirect ISORROPIA-II estimations showed that the atmosphere in the Iasi area might be ammonia rich during both the cold and warm seasons, enabling enough NH 3 to be present to neutralize H 2 SO 4 , HNO 3 , and HCl acidic components and to generate fine-particulate ammonium salts, in the form of (NH 4) 2 SO 4 , NH 4 NO 3 , and NH 4 Cl. ISORROPIA-II runs allowed us to estimate that over the warm season ∼ 35 % of the total analysed samples had very strongly acidic pH (0-3), a fraction that rose to ∼ 43 % over the cold season. Moreover , while in the cold season the acidity is mainly accounted for by inorganic acids, in the warm ones there is an important contribution by other compounds, possibly organic. Indeed, changes in aerosol acidity would most likely impact the gasparticle partitioning of semi-volatile organic acids. Overall, we estimate that within the aerosol mass concentration the ionic mass brings a contribution as high as 40.6 %, with the rest still being unaccounted for.
Chemical Engineering Journal
This work presents investigations on the gas-phase chemistry of phenol and the cresol isomers per... more This work presents investigations on the gas-phase chemistry of phenol and the cresol isomers performed in a 1080 l quartz glass reactor in Wuppertal and in a large-volume outdoor photoreactor EUPHORE in Valencia, Spain. The studies aimed at clarifying the oxidation mechanisms of the reactions of these compounds with OH and NO 3 radicals. Product investigations on the oxidation of phenol and the cresol isomers initiated by OH radicals were performed in the 1080 l quartz glass reactor with analyses by in situ FT-IR absorption spectroscopy. The primary focus of the investigations was on the determination of product yields. This work represents the first determination and quantification of 1,2dihydroxybenzenes in the OH oxidation of phenolic compounds. Possible reaction pathways leading to the observed products have been elucidated. The products observed and their respective yields were as follows: reactant products yield (%) phenol 1,2-dihydroxybenzene 1,4-benzoquinone 2-nitrophenol 80.4 ± 12.1 3.7 ± 1.2 5.8 ± 1.0 ortho-cresol 1,2-dihydroxy-3-methylbenzene methyl-1,4-benzoquinone 6-methyl-2-nitrophenol 73.4 ± 14.6 6.8 ± 1.0 6.8 ± 1.5 meta-cresol 1,2-dihydroxy-3-methylbenzene 1,2-dihydroxy-4-methylbenzene methyl-1,4-benzoquinone 5-methyl-2-nitrophenol 3-methyl-2-nitrophenol 68.6 ± 13.4 9.7 ± 2.7 11.3 ± 2.5 4.4 ± 1.5 4.3 ± 1.6 para-cresol 1,2-dihydroxy-4-methylbenzene 4-methyl-2-nitrophenol 64.1 ± 11.3 7.6 ± 2.2 The rate constants for the reaction of OH radicals with dihydroxy(methyl)benzenes and (methyl)benzoquinones were determined using the relative rate technique. All of the following data represent first-time determinations of the rate constants. At 1000 mbar total pressure and 300± 2 K, the following rate constants (in 10-11 cm 3 molecule-1 s-1) were obtained: reactant k OH 1,2-dihydroxybenzene 10.4 ± 2.1 1,2-dihydroxy-3-methybenzene 20.5 ± 4.3 1,2-dihydroxy-4-methylbenzene 15.6 ± 3.3 1,4-benzoquinone 0.46 ± 0.1 methyl-1,4-benzoquinone 2.35 ± 0.47 41.3 ± 3.7 85.0 ± 10.2 44.3 ± 3.3 86.2 ± 7.0 This work has vastly improved the knowledge on the distribution of oxidation products from the reaction of OH with phenol and the cresol isomers and also significantly improved it for the NO 3 reactions. The product studies have allowed the construction of tentative oxidation mechanisms for these selected aromatic compounds which are required for atmospheric chemical transport models.
International Journal of Chemical Kinetics, 2015
ABSTRACT The gas-phase ozonolysis of three methylated alkenes, i.e., trans-2,2-dimethyl-3-hexene ... more ABSTRACT The gas-phase ozonolysis of three methylated alkenes, i.e., trans-2,2-dimethyl-3-hexene (22dM3H), trans-2,5-dimethyl-3-hexene (25dM3H), and 4-methyl-1-pentene (4M1P), has been investigated in the presence of sufficient hydroxyl radical scavenger in a laminar flow reactor at ambient temperature (296 ± 2 K) and P = 1 atm of dry air (RH ≤ 5%). Ozone levels in the reactor were monitored by an automatic analyzer. Alkene and gas-phase product concentrations were determined via online sampling either on three-bed adsorbent cartridges followed by thermodesorption and GC/FID-MS analysis or on 2,4-dinitrophenylhydrazine (DNPH) cartridges for subsequent HPLC/UV analysis. Reaction rate coefficients of (3.38 ± 0.12) × 10−17 for 22dM3H and (2.71 ± 0.26) × 10−17 for 25dM3H, both in cm3 molecule−1 s−1 units, have been obtained under pseudo–first-order conditions. Primary carbonyl products have been identified for the three investigated alkenes, and branching ratios are reported. In the case of 4M1P ozonolysis, the yield of a Criegee intermediate was indirectly determined. Kinetics and product study results are compared to those of literature when available. This work represents the first investigation of reaction products in the ozonolysis of 22dM3H, 25dM3H, and 4M1P in a flow reactor.
The journal of physical chemistry. A, Jan 22, 2015
In this work, we study the gas-phase pyrolysis of benzyl azide (BA, C6H5CH2N3) using ultraviolet ... more In this work, we study the gas-phase pyrolysis of benzyl azide (BA, C6H5CH2N3) using ultraviolet photoelectron spectroscopy (UVPES) and matrix-isolation infrared (IR) spectroscopy, together with electronic structure calculations and Rice-Ramsperger-Kassel-Marcus (RRKM) calculations. It is found that BA decomposes via N2 elimination at ca. 615 K, primarily yielding benzenemethaninime. Other end products include HCN and C6H6. N-methyleneaniline is not detected, although its formation at higher temperature is foreseen by RRKM calculations.
The Journal of Physical Chemistry A, 2015
Anthropogenic activities are the main source of nitrophenols and chlorophenols in the atmosphere.... more Anthropogenic activities are the main source of nitrophenols and chlorophenols in the atmosphere. Nitro and chlorophenols have a high potential to form ozone and secondary organic aerosol, thus investigations on the major photo oxidation pathways of these compounds are important to assess their contribution to urban air pollution and human health. Presented here are rate coefficients determined at atmospheric pressure and (298 ± 2) K using a relative kinetic method for the reactions of chlorine atoms with 2-chlorophenol (2ClP), 2-nitrophenol (2NP) and four methyl-2-nitrophenol (2-nitrocresol, nM2NP (n=3,4,5,6)) isomers. The following rate coefficients (in units of cm3 molecule-1 s-1) have been obtained: (5.9 ± 1.5) × 10-12 for 2ClP, (6.8 ± 2.3) × 10-12 for 2NP, and (14.0 ± 4.9) × 10-11, (4.3 ± 1.5) × 10-11, (1.94 ± 0.67) × 10-11 and (2.68 ± 0.75) × 10-11 for the four methyl-2-nitrophenol isomers 3M2NP, 4M2NP, 5M2NP and 6M2NP, respectively. This study represents the first kinetic investigation for the reaction of chlorine atoms with all the nitrophenols. In addition, to assist in the interpretation of the results, rate coefficients for the reactions of Cl atoms with the cresol ortho, meta and para isomers have been determined for the first time. The rate coefficient for the reaction with 2ClP is in good agreement with previous data and the relative reactivity of 2NP, 4M2NP, 5M2NP and 6M2NP can be rationalized based on known substituent effects. The rate coefficient for 3M2NP is anomalously large; the observation of significant NO2 production in only this reaction suggests that an ipso substitution mechanism is the cause of the enhanced reactivity.
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Papers by Romeo-Iulian Olariu