Absence Of Naphthalene Research Articles

Naphthalene-modulated microporous carbon layers of LiFePO4 improve the high-rate electrochemical performance

Abstract Carbon layers with microporous structures fine-modulated by naphthalene (NAP) were prepared to coat on LiFePO4, aiming to enhance the Li+ diffusion coefficient for Li-ion batteries. Characterized by BET, XRD, TEM, EIS, etc., it is indicated that in the presence of NAP, the carbon-coated LiFePO4/C-NAP composites have the enlarged micropore size of 1.66 nm and the enhanced Li+ diffusion coefficient of 2.83 × 10−12 cm2 s−1, which is about five times higher than that of LiFePO4/C prepared in the absence of NAP. At a high rate of 20 C, the discharge capacity of the LiFePO4/C-NAP is up to 120.1 mA h g−1 and maintains a good retention rate of 93.2% after 400 cycles. It is suggested that the NAP-modulated carbon coating is a promising route to accelerate the Li-ion diffusion rate and enhance the electrochemical performance for lithium ion batteries.

Molecularly imprinted polymer membrane for the removal of naphthalene from petrochemical wastewater streams

AbstractThe aim of this work was the preparation of molecularly imprinted membrane (MiM) using polysulfone (PSf) polymer for targeted removal of polycyclic aromatic hydrocarbons from petrochemical wastewater. Naphthalene was opted as a model pollutant, and the imprinted membrane was fabricated by phase inversion technique. Nonimprinted membrane (NiM) was also prepared in the absence of naphthalene and used as a reference. The polymers (MiM/NiM) were systematically characterized using different characterization techniques. The selectivity property of the membranes was evaluated by their ability in separation of naphthalene through filtration tests. Results showed that in comparison with NiM, the imprinted membrane exhibits higher affinity toward naphthalene molecules. It was found that the selectively of MiM is 2.27‐fold more than that of the corresponding NiM. This finding can be encouraging from industrial applications points of view.

Influence of naphthalene biodegradation on the adhesion of Pseudomonas putida NCIB 9816-4 to a naphthalene-contaminated soil

In an earlier study, Pseudomonas putida NCIB 9816-4, which was one of the most studied naphthalene-degrading bacteria, showed the preferred adhesion to the naphthalene-contaminated soil when it was in the exponential growth phase. The adhesion was found to take place through a hydrophobic interaction. We postulated that the surface hydrophobicity of P. putida NCIB 9816-4 in the exponential growth phase might be increased during the uptake of naphthalene, which caused the preferred adhesion to the naphthalene-contaminated soil. To verify this postulate, a plasmid-cured strain of P. putida NCIB 9816-4 was obtained in this study and compared with the wild-type for adhesion to the naphthalene-contaminated soil. Only the wild-type in the exponential growth phase showed increased adhesion to naphthalene-contaminated soil. The water contact angles of the two strains were measured in the presence and in the absence of naphthalene as indices of surface hydrophobicity. The water contact angle of the wild-type increased in the presence of naphthalene, whereas that of the cured strain did not change. We conclude that the uptake of naphthalene during naphthalene biodegradation in the exponential growth phase of P. putida NCIB 9816-4 made the cell surface more hydrophobic, resulting in increased adhesion to naphthalene-contaminated soil.

Desulphurization of organic sulphur from coal by electron transfer process with Co 2+ ion

This paper reports the results of desulphurization of organic sulphur from a subbituminous Meghalaya coal by the electron transfer process accomplished with the metal ion Co 2+. The process was studied both in presence and absence of naphthalene which is used as an electron transfer agent. Temperature dependence on desulphurization unfolded that as the temperature is raised from 25 to 50 °C, there is increase in desulphurization performance. Model organic sulphur compounds study revealed that the desulphurization process is effective with aliphatic type of compounds. Infrared spectroscopic study revealed the release of easily removable sulphur compounds as the band intensities due to −S O and −SO 2 groups have declined considerably in their respective regions in the desulphurized coals. The degree of desulphurization is 28.5 wt.% in the presence of naphthalene and 24.6 wt.% in absence of naphthalene, both at 4 h and 50 °C. The sulphur extrusion process is continuous and application of a first-order kinetic model produced specific rate constants of the desulphurization reaction in the two systems, at different temperatures, which falls in the range of (1.3–2.9)×10 −5 s −1. The activation energy of the sulphur-loss reaction in the system containing naphthalene (26.8 kJ mol −1) is about 12% lower than that of the system without naphthalene (30.6 kJ mol −1). The frequency factor of the sulphur removal reaction in the systems have been found to be in the range of 0.8–3.2 s −1, suggesting low amount of successful collisions and an associated type of reaction. The desulphurization reaction is nonspontaneous in nature, proceeds with the absorption of heat and there is reduction in the degree of disorderliness in the system as predicted by the transition state theory.

Electron-Transfer-Induced Desulfurization of Organic Sulfur from Sub-bituminous Coal

The intent of this paper is to investigate the effects of leaching time and temperature on the level of desulfurization of organic sulfur by an electron-transfer process involving the transition-metal ion Ni2+ from a sub-bituminous Indian coal. The electron-transfer process was accomplished both in the presence and the absence of naphthalene with unoxidized and oxidized samples. Desulfurization has been determined to be greater in oxidized samples. The presence of naphthalene enhanced the amount of desulfurization both in unoxidized and oxidized samples, revealing that it serves as an excellent electron-transfer agent. Increases in reaction time and temperature increased the level of desulfurization. The electron-transfer process, in the presence of naphthalene, succeeded in removing a maximum of 16.3 wt % organic sulfur from unoxidized coal and 18.7 wt % from oxidized coal at 50 °C and 4 h. Study of a model sulfur compound indicated that the desulfurization is primarily due to aliphatic-type compounds, s...

Sensitization of the radiation-induced chain oxidation of aromatic amines in polymer films (038)

The sensitization of the chain redox reaction in γ-irradiated solid films of poly(vinyl chloride) (PVC), containing N, N, N ′, N ′-tetramethyl-4,4 ′-diaminodiphenylmethane (Am), CBr 4 and naphthalene, was investigated by the electron spin resonance and optical spectroscopy methods. The ESR spectra of the γ-irradiated PVC films at 77 K with the additives of Am, CBr 4 and naphthalene were studied. The effects of radiation dose and annealing temperature on the transformation radicals were investigated. The spectra of radicals, taking part in the chain reaction, were separated and identified. The radiation-chemical yields of these radicals and their thermal stability were determined. The dependencies of radical concentration on the annealing temperature for samples in the presence and in absence of naphthalene were compared. It was established that the addition of naphthalene up to 0.2 kmol/m 3 results in an increase of the chain reaction yield from 80 to 150 particle/100 eV in the case if the samples are irradiated at 300 K. If the irradiation is made at 77 K, the yield of oxidized amine Am + after annealing at 293 K rises from 20 to 45 particle/100 eV as a result of action of naphthalene. The analysis of ESR spectra, made by a computer subtraction, showed that the radiation-chemical yield of free radicals Am , initiating the chain reaction, is not changed in consequence of the addition of naphthalene. Therefore we suggest that the sensitizing activity of naphthalene is caused by increasing the polymer chain flexibility and, consequently, the diffusion coefficient of active CBr 3 radicals, the chain propagating species.

Naphthalene, phenanthrene and surfactant biodegradation.

The impact of surfactants on naphthalene and phenanthrene biodegradation and vice versa after surfactant flushing were evaluated using two anionic surfactants: sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS); and two nonionic surfactants: POE (20) sorbitan monooleate (T-maz-80) and octylphenol poly(ethyleneoxy) ethanol (CA-620). Naphthalene and phenanthrene biodegradation varied differently in the presence of different surfactants. Naphthalene biodegradation was not impacted by the presence of SDS. In the presence of T-maz-80 and CA-620, naphthalene biodegradation occurred at a lower rate (0.14 d(-1) for T-maz-80 and 0.19 d(-1) for CA-620) as compared to un-amended control (0.29 d(-1)). Naphthalene biodegradation was inhibited by the presence of SDBS. In the presence of SDS, phenanthrene biodegradation occurred at a lower rate (0.10 d(-1) as compared to un-amended control of 0.17 d(-1)) and the presence of SDBS, CA-620 and T-maz-80 inhibited phenanthrene biodegradation. The surfactants also responded differently to the presence of naphthalene and phenanthrene. In the presence of naphthalene, SDS biodegradation was inhibited; SDBS and T-maz-80 depleted at a lower rate (0.41 d(-1) and 0.12 d(-1) as compared to 0.48 d(-1) and 0.22 d(-1)). In the absence of naphthalene, CA-620 was not degradable, while in the presence of naphthalene, CA-620 began to degrade at a comparatively low rate (0.12 d(-1)). In the presence of phenanthrene, SDS biodegradation occurred at a lower rate (1.2 d(-1) as compared to 1.68 d(-1)) and a similar trend was observed for T-maz-80. The depletion of SDBS and CA-620 did not change significantly. The choice of SDS for naphthalene-contaminated sites would not adversely affect the natural attenuation of naphthalene, in addition, naphthalene was preferentially utilized to SDS by naphthalene-acclimated microorganisms. Therefore, SDS was the best choice. T-maz-80 was also found to be usable in naphthalene-contaminated sites. For phenanthrene contaminated sites, SDS was the only choice.

Electron transfer process. Part 2. Desulphurization of organic sulphur from feed and mercury-treated coals oxidized in air at 50, 100 and 150°C

In this paper, experiments have been undertaken to understand the nature of organic sulphur compounds retained after oxidation at 50,100 and 150°C for both feed and Hg-treated coals as well as the extent of desulphurization by the electron transfer process. It has been observed that oxidation of coal in air resulted in the predominant formation of disulphide compounds. Besides these compounds, aliphatic thiol compounds seem to have been leached out by the electron transfer process. Maximum desulphurization achieved by the electron transfer process carried out in absence of naphthalene is 19.17wt% in feed coal and 17.78wt% in Hg-treated coal of the total organic sulphur for the samples oxidized at 100°C. The desulphurization reaction has been found to follow pseudo-first-order kinetics and their rate constants have been calculated. The activation energies and frequency factors calculated for these coal samples are found to be in the range 21.28–25.53kJmol−1 and 5.01×10−4–28.18×10−4min−1, respectively. Kinetic studies reveal that the desulphurization reaction is non-spontaneous in nature which is further supported by the negative value of ΔS and positive value of ΔG. Low frequency factors and negative values of ΔS suggest that desulphurization by electron transfer process is an associated reaction. Although the positive value of ΔH attributes the endothermicity of the desulphurization reaction which requires input of energy for effective desulphurization, but the energy liberated during the formation of ion-radicals is utilized for rupture of bonds in those organic sulphur compounds which contain relatively weak C–S as well as S–S bonds. Total desulphurization (summation of oxidative desulphurization and desulphurization by electron transfer process, in absence of naphthalene) of organic sulphur is found to be 27.38wt% in feed coal and 28.45wt% in Hg-treated coals. This suggests that the presence of Hg2+ ion and naphthalene has no significant influence on desulphurization. The results of this work have considerable technological interest.

Fullerene blacks and cathode deposits derived from plasma arcing of graphite with naphthalene

Fullerene black and cathode deposits formed by arcing graphite with naphthalene have been examined. Micro-Raman, transmission electron microscopy and differential thermal analysis show that fullerene blacks produced in the presence of naphthalene are more graphite like than those prepared in its absence. These techniques also show that the cathode deposits are altered by the presence of naphthalene in the feed material. The mixture of nanotubes so formed has a larger average void size than that formed in the absence of naphthalene. The results support proposed mechanisms of nanotube formation that involve growth by incorporation of carbon atoms into open tubes. They also show that naphthalene can be directly incorporated into fullerene black and thereby increase the number of hexagonal sheet structures in the carbon deposit.

Electron-Acceptor Behavior of 2,4,7,9-Tetracarba-nido-dodecaborane(12) with Group 1 and Group 2 Metals: Syntheses and Crystal Structures of [(THF)4Li][(SiMe3)4C4B8H9] and [(THF)2Mg(SiMe3)4C4B8H8

The room-temperature reaction between a THF solution of 2,4,7,9-tetracarba-nido-dodecaborane(12) (SiMe3)4C4B8H8 and finely cut excess lithium or magnesium metal, in the absence of naphthalene and aromatic solvents, produced either {[(THF)4Li][(SiMe3)4C4B8H9]} (1) as an EPR-silent transparent crystalline solid in 41% yield or [(THF)2Mg(SiMe3)4C4B8H8] (2) as an off-white crystalline solid in 88% yield. While the solid-state structure of 1 showed a single anionic [(SiMe3)4C4B8H9]- unit that was well-separated from a discrete [Li(THF)4]+ cation, the structure of 2 is that of a novel magnesacarborane in which the carborane cage incorporates both electron-precise and electron-deficient carbon and boron atoms.

Naphthalene oxygenase fromCorynebacterium renale: Characterisation and mechanism of oxygenation

The formation ofcis-l,2,-dihydroxy-l,2,-dihydronaphthalene from naphthalene by naphthalene oxygenase, purified fromCorynebacterium renale ATCC 15075, was demonstrated to involve oxidation of a mol NADH and consumption of one mol oxygen. The enzyme contains one g-atom Fe2+ and one FAD. Catalase inhibited product formation and H2O2 could substitute for NADH in the reaction. Superoxide dismutase inhibited enzyme activity when either NADH or H2O2 was present; the generation of superoxide anion on addition of NADH to the enzyme, in the absence of naphthalene, was detected by the nitro blue tetrazolium reduction method. Hydroxyl radical scavengers, ethanol, mannitol and sodium benzoate, inhibited product formation when either NADH or H2O2 was present. Electron spin resonance studies, under aerobic conditions, indicated that iron of the enzyme underwent valence changes during the course of the reaction

THE IN VITRO PHOTOCHEMISTRY OF BIOLOGICAL MOLECULES—II. THE TRIPLET STATES OF β‐CAROTENE AND LYCOPENE EXCITED BY PULSE RADIOLYSIS

Abstract— –Pulse radiolysis has been used to excite the triplet states of β‐carotene (τ# 9μ sec) and lycopene (τ= 8μsec) in hexane solution, both in the presence and absence of naphthalene as a triplet sensitiser. The absorption spectra of both triplets have been measured in the range 430–550 nm and have thus been extended into the region of the corresponding singlet absorptions. The overlap of the triplet and singlet spectra is discussed in relation to in vivo studies. Extinction coefficients of 1.3±0.1 × 105 l/mole cm for β‐carotene triplet 515 nm and 3.9±0.2 × 105 l/mole cm for lycopene triplet at 525 nm were obtained. Isomerisation of the all‐trans polyenes used was detected and preliminary measurements indicate that the yield of isomerisation was greater than the triplet yield. The rate of triplet energy transfer from naphthalene to β‐carotene was estimated to be 1.5 × 1010 l/mole sec. The corresponding value for lycopene was 1.4× 1010 l/mole sec. The measured efficient quenching of triplet β‐carotene by oxygen may occur by an energy transfer mechanism, leading to the formation of singlet oxygen (1Δg. This would suggest that the triplet energy level of β‐carotene lies between 121 and 94 kJ mole‐1.

Formation of amines from aromatic hydrocarbons and molecular nitrogen during the reducing fixation of N2

We have found that the fo rmat ion of amines during the reducing fixation of ni t rogen can in a numb er of c a se s a lso occur d i rec t ly f r o m the a rom a t i c hydroca rbons . Thus N 2 r eac t s at 20~ with a mix ture of naphthalene and excess meta l l i c l i thium in t e t r ahydro fu ran to fo rm (after hydro lys i s of the reac t ion mixture) ammonia and smal l amounts of c_,-naphthylamine.* S imi la r ly , in the reac t ion of ni t rogen with l i thium and diphenyl, ammonia and a mix tu re of o and p-aminodiphenyls a re obtained. In the absence of naphthalene (or diphenyl) }42 undergoes a lmos t no reac t ion with Li under these conditions. The yie lds of amines and a m monia depend on the concent ra t ion of the a ro ma t i c hydroca rbon and on the mo la r ra t io of Li to hydrocarbon . F o r Li:naphthalene = 16:1, the yield of c~-naphthylamine is 0.2-0.3% based on naphthalene (naphthalene concent ra t ion 0.8 M, N 2 p r e s s u r e 100 arm).