Pyridine Concentration Research Articles

Liquid liquid equilibria of imidazolium based ionic liquid + pyridine + hydrocarbon at 298.15 K: Experiments and correlations

In this work, 1-ethyl 3-methylimidazolium methylsulfonate [EMIM][MeSO3], 1-ethyl 3-methylimidazolium ethylsulfate [EMIM][EthSO4] and 1-ethyl-3-methylimidazolium acetate [EMIM][Ac] were investigated as green solvents for the denitrification of diesel oil at T=298.15K and atmospheric pressure. The liquid liquid equilibrium (LLE) data for the ternary mixture of [EMIM][MeSO3] (1)+pyridine (2)+n-pentane/isooctane (3), [EMIM][EthSO4] (1)+pyridine (2)+1-pentane/isooctane (3) and [EMIM][Ac] (1)+pyridine (2)+n-pentane/isooctane (3) systems were experimentally determined at ambient conditions. In all the systems, the tie lines had a negative slope at higher concentrations of pyridine, implying higher quantity of ionic liquid is required for the separation of pyridine from hydrocarbon. It was found that at lower concentrations of pyridine in feed, [EMIM][Ac] and [EMIM][MeSO3] are the potential solvents for the extraction of pyridine from n-pentane and isooctane respectively. The experimental results were well correlated with predicted values via NRTL and UNIQUAC models. The average RMSD obtained in NRTL and UNIQUAC models for all the six systems were 1.15% and 1.9% respectively.

Removal of pyridine from water by pervaporation using crosslinked and filled natural rubber membranes

AbstractNatural rubber (NR) of grade RSS4 was efficiently cured (crosslinked) by using sulfur: accelerator weight ratio of 1 : 4. This was further compounded with high abrasion grade carbon black filler (grade N330) with three different doses, that is, 5, 10, and 20 wt % of rubber to form three different filled and crosslinked membranes designated as NR5, NR10, and NR20, respectively. These filled rubber membranes and one unfilled but efficiently cured membrane, that is, NR0, were used for pervaporative removal of low concentration of pyridine from water. The filled membranes were found to show higher pyridine selectivity but lower flux than the unfilled membrane. All of these membranes showed reasonably good range of flux and pyridine selectivity. Among all of the used membranes, NR5‐filled membrane yielded high pyridine selectivity (122) with reasonable thickness normalized flux (2.2 kg m−2 h−1 mμ) at 40°C for 0.5 wt % of pyridine in water. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Is Loss in Odor Sensitivity Inevitable to the Aging Individual? A Study of “Successfully Aged” Elderly

Previous research suggests that the variability in odor detectability is large in the elderly population. Compared to young adults, most elderly demonstrate poor detectability although some show normal ability. To shed light on why there is this discrepancy among the elderly, absolute detection thresholds for pyridine odor were determined by the method of constant stimuli. Young adults (20–24 years) were compared with elderly (77–87 years) who were “successfully aged” with respect to medical health and cognitive ability. The results showed that these elderly and young adults had very similar mean detection thresholds for pyridine (105 and 100 ppb, respectively) and psychometric detection functions (identical slopes with increasing pyridine concentration). These results imply that deficits in odor detectability may not be inevitable to the aging individual and that factors secondary to aging, such as poor medical health status and cognitive decline, may contribute to deficits in odor detectability in normal aging.

Cation exchange chromatographic separation of amines through fiber supported solid membrane

The cation exchange chromatographic separation of pyridine, monoethanol and triethanol amines have been explored from source to receiving phase through the fiber supported solid membrane. The fibers supported solid membranes were prepared by chemically modification of cellulose fibers with introducing the carboxylic acid ion exchanging groups. The experimental variables explored were concentration of pyridine, monoethanol and triethanol amines (10 -2 to 10-6 M) in the source solution, HCl (0.01 to 0.20 M) in the receiving phase and stirring speed (50-130 rpm) of the bulk source and receiving phase. The efficiency has been evaluated of fiber supported solid membrane system for the transport of pyridine, monoethanol and triethanol amines from the source solution to receiving phase through the fiber supported solid membrane. The pre-concentration was studied of pyridine, monoethanol and triethanol amines from the dilute solutions.Key words: Pyridine, monoethanol and triethanol amines, fiber supported solid membrane; ion exchangeDOI: http://dx.doi.org/10.3329/cerb.v15i1.6788 Chemical Engineering Research Bulletin 15 (2011) 25-29

Novel structural variation of silver(I)–pyridine complexes in nitromethane as studied by X-ray absorption spectroscopy

The XAFS spectra were measured at around the Ag K-edge of the Ag(I) ion in nitromethane (NM) with a variety of concentrations of pyridine (PY). In NM without PY, the Ag(I) ion is tetrahedrally solvated by four NM molecules similar to those in most solvents. The Ag–O bond length in NM solvent is longer than that in aqueous solution, indicating the low donating ability of NM. The mono-, bis-, tris-, and tetrakis-pyridine complexes are formed in NM by the addition of PY. The EXAFS analyses reveal that the structure of the formed PY complex in NM is linear for Ag(py)(nm) +, linear for Ag ( py ) 2 + , triangular for Ag ( py ) 3 + , and tetrahedral for Ag ( py ) 4 + . The longer Ag–O bond length for Ag(py)(nm) + than that for Ag ( nm ) 4 + and the release of bound NM molecules at the formation of Ag(py)(nm) + are interpreted to be due to the strong σ donating property of PY. The Ag–N bond length (220 pm) for Ag ( py ) 3 + is intermediate between 216 pm for Ag ( py ) 2 + and 228 pm for Ag ( py ) 4 + . The formation equilibria of Ag ( py ) 3 + and Ag ( py ) 4 + are analyzed on the basis of the changeover of EXAFS spectra as a function of the total concentrations of Ag + and PY in NM.

Isolation and Identification of Achromobacter sp. DN-06 and Evaluation of Its Pyridine Degradation Kinetics

We report the isolation of a new bacterium species (named as DN-06) that degrades pyridine, a model compound containing both carbon and nitrogen, from the aerobic activated sludge in a coking wastewater treatment plant. DN-06 was identified as Achromobacter sp. using 16S rDNA sequence analysis. In batch culture, more than 95% of pyridine (500 mg/L) was degraded within 18 h by DN-06 grown at 35°C and pH 8 with agitation at 170 rpm. Degradation experiments of pyridine at different initial concentrations (50–4,300 mg/L) revealed that pyridine was an inhibitory substrate, and that neither yield coefficient Y nor endogenous decay coefficient K d was a constant. The values of Y and K d were 0.55–0.74 and 0.0032–0.0057 h−1, respectively. Five kinetic models (Haldane, Yano, Aiba, Webb, and Monod) were fitted to the experimental growth kinetic data. Models of Haldane and Yano (correlation coefficient R 2 = 0.929) were the most suitable models. For Haldane kinetic model, the values of μ max, K s, and K i were 0.161 h−1, 142.6 mg/L, and 4234.8 mg/L, respectively. The large values of Y and K i indicated that DN-06 had good tolerance against high pyridine concentrations. These results indicated possible future applications of Achromobacter sp. DN-06 in removing pyridine from industrial wastewaters, as well as in destroying pyridine in concentrated solutions during further treatment of trial water coupling with adsorption technology.

Multiresonant Coherent Multidimensional Vibrational Spectroscopy of Aromatic Systems: Pyridine, a Model System

Multiresonant four wave mixing has been used to measure the coherent multidimensional spectroscopy (CMDS) of representative aromatic ring modes using pyridine as a model system. This work identifies the cross-peaks that appear between several modes and measures their coherent and incoherent dynamics. The work also explores the consequences of using multiresonant CMDS for molecules with transition moments that are typical of most vibrational modes. Typically, CMDS experiments rely on using transitions with exceptionally large transition moments. To observe cross-peaks, the pyridine concentration was raised until absorption effects became very important. These effects interfere with the parametric CMDS coherence pathways, but they do not make important contributions to the nonparametric pathways.

Bioaugmentation and Adsorption Treatment of Coking Wastewater Containing Pyridine and Quinoline Using Zeolite-Biological Aerated Filters

Bioaugmented zeolite-biological aerated filters (Z-BAFs), i.e. adding isolated degrading bacteria into the BAFs with zeolite as fillings, were designed to treat coking wastewater containing high concentrations of pyridine and quinoline and to explore the bacterial community of biofilm on the zeolite surface. The investigation was carried out for 91 days of column operation and the treatment of pyridine, quinoline, total organic carbon (TOC), and ammonium was shown to be highly efficient by bioaugmentation and adsorption. Biomass determination and bacterial diversity detection based on 16S rDNA and rRNA techniques supported the treatment data and indicated that bioaugmentation could recover the bacterial richness and diversity from pyridine and quinoline loading shocks. However, bioaugmentation accelerated the shift of the bacterial community structure resulting in a more distinct difference from the starting community. Clone library analysis revealed that pyridine and quinoline were more harmful to Bacterodietes among all ingenious bacteria, and bioaugmentation promoted the growth of Planctomycetes in the biofilm. Moreover, the introduced bacteria did not remain dominant in the bioaugmented biofilm, indicating the indigenous degrading bacteria played the most significant role in the treatment. This bioaugmented Z-BAF method was shown to be an alternative technology for the treatment of wastewater containing pyridine and quinoline or other N-heterocyclic aromatic compounds.

GC–MS analysis of water-soluble organics in atmospheric aerosol: Response surface methodology for optimizing silyl-derivatization for simultaneous analysis of carboxylic acids and sugars

This paper describes the development of a derivatization procedure — silylation using N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA) — for the simultaneous GC–MS analysis of a wide range of water-soluble organics in atmospheric aerosols. The reaction operating conditions were optimized using the response surface methodology (RSM) including central composite design (CCD) in order to achieve the highest response for a large number of dicarboxylic acids and sugars. The factors considered were: (i) reaction temperature (50–90 °C), (ii) the reaction duration (60–120 min), (iii) reagent concentrations (10–100% of the total solution volume) and (iv) pyridine concentration (0–50% of the derivatization reagent). On the basis of RSM and experimental evidence, the optimum derivatization conditions were defined as reaction temperature of 75 °C, reaction duration of 70 min, BSTFA reagent concentration of 55% and pyridine concentration of 35%. The optimized protocol was extended to a broader range of 22 target analytes that are relevant chemical markers, i.e., 15 carboxylic acids and 7 sugars. In addition, the applicability of the optimized procedure was verified in environmental matrices from PM filters collected under different conditions, i.e., different seasons (summer vs. winter), different sampling sites (urban vs. rural), different particle size dimensions (PM 2.5 vs. PM 1).

Hydrolysis of 1-(X-substituted-benzoyl)-4-aminopyridinium ions: effect of substituent X on reactivity and reaction mechanism

A kinetic study is reported for hydrolysis of 1-(X-substituted-benzoyl)-4-aminopyridinium ions 2a-i, which were generated in situ from the nucleophilic substitution reaction of 2,4-dinitrophenyl X-substituted-benzoates 1a-i with 4-aminopyridine in 80 mol% H(2)O/20 mol% DMSO at 25.0 ± 0.1 °C. The plots of pseudo-first-order rate constants k(obsd) vs. pyridine concentration are linear with a large positive intercept, indicating that the hydrolysis of 2a-i proceeds through pyridine-catalyzed and uncatalyzed pathways with the rate constant k(cat) and k(o), respectively. The Hammett plots for k(cat) and k(o) consist of two intersecting straight lines, which might be taken as evidence for a change in the rate-determining step (RDS). However, it has been proposed that the nonlinear Hammett plots are not due to a change in the RDS but are caused by stabilization of 2a-i in the ground state through a resonance interaction between the π-electron-donor substituent X and the carbonyl functionality. This is because the corresponding Yukawa-Tsuno plots exhibit excellent linear correlations with ρ(X) = 1.45 and r = 0.76 for k(cat) while ρ(X) = 1.39 and r = 0.72 for k(o). A possibility that the hydrolysis of 2a-i proceeds through a concerted mechanism has been ruled out on the basis of the large ρ(X) values. Thus, the reaction has been concluded to proceed through a stepwise mechanism in which the leaving group departs after the RDS since OH(-) is more basic and a poorer nucleofuge than 4-aminopyridine.

Dual substrates biodegradation kinetics of m-cresol and pyridine by Lysinibacillus cresolivorans

Phenols and N-heterocyclic compounds are found to co-exist in actual wastewater, especially in petrochemical and coking wastewater. Lysinibacillus cresolivorans, a bacterium capable of phenol-biodegradation was used to study the substrate interactions of m-cresol and pyridine as single and dual substrates. The cell growth and substrate biodegradation kinetics were also investigated with initial m-cresol concentrations varying from 0 to 1200mg/L and pyridine concentrations varying from 0 to 150mg/L. The single substrate kinetics was well described by the Haldane kinetic models. The single-substrate parameter values of m-cresol on cell growth were μmax=0.89h−1, Ks=426.25mg/L, Ki=51.26mg/L and μmax=0.0925h−1, Ks=60.28mg/L, Ki=16.17mg/L for cell growth on pyridine. Inhibitory effects of substrates were observed when cells were grown on the mixed substrates. The interaction parameter Im,p (0.76) was greater than Im,p (0.11), which indicated that m-cresol inhibited the utilization of pyridine much more than pyridine inhibited the biodegradation of m-cresol. The study showed a good potential of L. cresolivorans in degrading mixed substrates of m-cresol and pyridine.

Ultrasound Assisted Pervaporation Separation of Pyridine/Water Mixtures Using Poly(vinyl alcohol)/Polyacrylonitrile Blend Membranes

AbstractPoly(vinyl alcohol)/polyacrylonitrile blend membranes were prepared to separate pyridine/water mixtures by pervaporation. The membranes were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of membrane composition, feed pyridine concentration, operating temperature, downstream pressure and ultrasound irradiation on the separation process were evaluated. The experimental results indicated that with increasing PVA mass ratio and operating temperature the permeate flux increased but the separation factor decreased, while with increasing feed concentration and downstream pressure the separation factor increased and the permeate flux decreased. It was observed that Ultrasound irradiation enhanced the permeate flux.

ChemInform Abstract: Laser Flash Photolysis Study of Substituent Effects on the Rate of 1,2- H Migration in a Series of Benzylchlorocarbenes.

Laser flash photolysis of para-substituted 3-chloro-3-benzyldiazirines in isooctane produces the corresponding carbenes, which react with pyridine to form ylides or undergo 1,2-H migration to form the (Z)- and (E)-β-chlorostyrenes. The rate for the 1,2-H migration is determined by plotting the pseudo-first-order rate constants for the growth of the ylide vs [pyridine] and extrapolating to zero pyridine concentration, in the case of (p-chlorobenzyl)chlorocarbene, the carbene decay can be monitored directly at 310 nm, whereas in [p-(trifluoromethyl)benzyl]chlorocarbene

Controlled Synthesis of Sb Nanostructures and Their Conversion to CoSb3 Nanoparticle Chains for Li-Ion Battery Electrodes

Nanostructured Sb was prepared through a simple polyol process. Either Sb nanoparticles (Sb NP) or nanowires (Sb NW) were obtained by adjusting the concentration of surfactant. Electrochemical analyses revealed that the resultant Sb crystals displayed high charge storage capacities as Li-ion battery electrodes and relatively poor cycling retention during the charge−discharge process. For instance, the capacity was 560−584 mA h/g during the second cycle, which decreased to 120−200 mA h/g during the 70th cycle at a rate of 0.2 C. Thus, Sb NPs were reacted with Co precursors to form one-dimensional (1-D) NP chains wrapped in a polyvinyl pyridine layer, and the length of the NP chains could be adjusted by varying the concentration of polyvinyl pyridine. Through a controlled annealing process, the polyvinyl pyridine layer was converted to amorphous carbon, which led to the formation of 1-D core−shell structures with CoSb3 NP chains entrapped in the carbon layer. Although CoSb3 NP chains with a carbon shell displayed a lower initial charge storage capacity than Sb nanostructures, improved cycling performance was observed. The capacity was 468 mA h/g during the second cycle, which dropped to 421 mA h/g during the 70th cycle at a rate of 0.2 C. Compared to CoSb3 produced via other techniques, CoSb3/C NP chains displayed higher cycling stability, because of the presence of a carbon buffer layer.

Aggregation of molecules in liquid pyridine and its solutions: Raman spectra and quantum-chemical calculations

In solutions of pyridine–propan-2-ol the ring vibration band of the hydrogen-bonded aggregates (H-aggregates) is shifted towards greater frequencies and changes its position with the change of pyridine concentration. The application of the mixture diluting method in a large amount of a neutral solvent (triple mixture) allows one to “resolve” the aggregates band structure. The observed doublet structure of the band is connected with the presence of two types of H-aggregates in liquid mixture. Quantum-chemical calculations confirm the high-frequency shift of 992 cm − 1 band of pyridine in the formation of aggregates with propan-2-ol. Similar calculations for isolated aggregates of pyridine–methyl alcohol show that several types of aggregates are possible including closed three-molecular H-aggregates of pyridine molecule with two molecules of methyl alcohol. Calculations show also that the pyridine molecules can form among themselves a weak dimer aggregate with two intermolecular hydrogen bonds.

Biodegradation of pyridine by Paracoccus sp. KT-5 immobilized on bamboo-based activated carbon

The performance of pyridine degradation by Paracoccus sp. strain KT-5 immobilized on bamboo-based activated carbon was investigated and compared with that of free cells. The results showed that Paracoccus sp. was able to attach well on the surface and pores of bamboo-carbon. Compared with freely suspended cells, the pyridine-degrading rate of the immobilized cells was higher when initial pyridine concentration was in the range of 489–1476 mg/L, suggesting that the efficiency of pyridine degradation by Paracoccus sp. strain KT-5 was enhanced significantly by immobilization technique. Additionally, the attached biomass on the bamboo-carbon increased from 391.9 to 430–500 mg/g during pyridine degradation. Furthermore, the semi-continuous degradation of pyridine by immobilized cells were carried out when the pyridine concentration was in the range of 293–1476 mg/L, the results demonstrated the feasibility and reusability of immobilized cells for pyridine degradation.

Effect of pyridine in electrolyte on the current–voltage characteristics in dye-sensitized solar cells

This study aimed to investigate the effect of pyridine in electrolyte on the photocurrent density–photovoltage ( J– V) characteristics in dye-sensitized solar cells. When the concentration of pyridine ( c p) in an electrolyte (0.1 M LiI and 0.05 M I 2 in acetonitrile) is increased from 0 to 0.4 M, the open-circuit voltage ( V oc) increased by 0.14 V, whereas the short-circuit photocurrent density ( J sc) decreased by 3.0 mA cm −2. The optimum c p for the maximum cell performance was around 0.1–0.2 M. The model calculation predicted that by increasing c p from 0 to 0.4 M, the electron diffusion coefficient ( D) decreases by more than one order of magnitude and the lifetime of conduction band-free electrons ( τ) increases by more than one order of magnitude, implying that the electron diffusion length ( L = D τ ) increases by 31%, whereas the electron injection flux from dye molecules to TiO 2 nanoporous films ( Φ) decreases by 28%.

Reduction of indium(III) at dropping mercury electrode in the presence of pyridine in aqueous and ethanol–water media

The reduction of indium(III) at dropping mercury electrode in aqueous as well as in 25% ethanol–water media in the presence of pyridine has been studied at a constant ionic strength (0.1 M KNO3) and at 30 and 40 °C. The reduction is diffusion-controlled but the electrode process is quasi-reversible in both media. The reversible half-wave potential values,E1/2r, have been obtained by Gelling’s method. The plot ofE1/2r versus pyridine concentration is a straight line and the number of ligands,j, was determined from the slope. This shows the formation of a single complex. The stability constant has been determined by Lingane’s method. In(III) forms one complex species with composition 1:1, [In(py)]3+. The values of thermodynamic parameters ΔG, ΔHand ΔSof the complexation reaction have also been determined at 30 °C.

Microbial degradation of pyridine by Paracoccus sp. isolated from contaminated soil

A pyridine-degrading strain was isolated from the contaminated soil near the pesticide plant, identified as Paracoccus sp., and designated as strain KT-5, on the basis of its partial 16S rRNA gene sequence analysis. The effect of different co-substrates including glucose, ammonium chloride and trace elements on biodegradation of pyridine by Paracoccus sp. KT-5 was investigated. The results showed that when the initial concentration of pyridine was about 900 mg L −1, 100 mg L −1 of glucose increased the growth of strain KT-5 and the removal of pyridine, but did not affect the release of nitrogen in the pyridine ring as ammonia. In addition, strain KT-5 was able to utilize 100 mg L −1 of glucose and 900 mg L −1 of pyridine simultaneously as the carbon source. 100 mg L −1 of ammonium chloride inhibited the growth of strain KT-5 in 900 mg L −1 of pyridine, and also slightly decreased the removal of pyridine, but did not affect the release of nitrogen in the pyridine ring as ammonia. However, lacking of trace elements not only inhibited the growth of strain KT-5 in 900 mg L −1 of pyridine, but also decreased the removal of pyridine, while it did not affect the release of nitrogen in the pyridine ring as ammonia.

Comparison of the adsorption mechanisms of pyridine in hydrophilic interaction chromatography and in reversed-phase aqueous liquid chromatography

The adsorption isotherms of pyridine were measured by frontal analysis (FA) on a column packed with shell particles of neat porous silica (Halo), using water–acetonitrile mixtures as the mobile phase at 295 K. The isotherm data were measured for pyridine concentrations covering a dynamic range of four millions. The degree of heterogeneity of the surface was characterized by the adsorption energy distribution (AED) function calculated from the raw adsorption data, using the expectation-maximization (EM) procedure. The results showed that two different retention mechanisms dominate in Per aqueous liquid chromatography (PALC) at low acetonitrile concentrations and in hydrophilic interaction chromatography (HILIC) at high acetonitrile concentrations. In the PALC mode, the adsorption mechanism of pyridine on the silica surface is controlled by hydrophobic interactions that take place on very few and ultra-active adsorption sites, which might be pores on the irregular and rugose surface of the porous silica particles. The surface is seriously heterogeneous, with up to five distinct adsorption sites and five different energy peaks on the AED of the packing material. In contrast, in the HILIC mode, the adsorption behavior is quasi-homogeneous and pyridine retention is governed by its adsorption onto free silanol groups. For intermediate mobile phase compositions, the siloxane and the silanol groups are both significantly saturated with acetonitrile and water, respectively, causing a minimum of the retention factor of pyridine on the Halo column.