Naphthalene In Aqueous Solution Research Articles

Mechanistic insights into the activation of nano calcium peroxide by pyrite coupled with citric acid for efficient naphthalene degradation: Performance and kinetics

In this research, pyrite was applied in synergy with citric acid for the activation of homemade nano-calcium peroxide to degrade naphthalene in aqueous solution. Results showed that over 90% of naphthalene could be removed within 180 min at a pH range of 3–9 due to the proton-releasing ability of pyrite. Hydroxyl radical, alkyl radical, and singlet oxygen were all detected by electron paramagnetic resonance spectra, with hydroxyl radical playing a dominant role in naphthalene degradation. The nano-calcium peroxide was mainly activated by Fe(II) leached from pyrite in homogeneous ways and the vital role of Fe(III) was also revealed. The superior naphthalene degradation in this system was attributed to the excellent electron-donating capacity of reductive sulfur species in Fe(II)/Fe(III) cycle and the increased concentration of available iron species by the chelating effect of citric acid. Meanwhile, the system showed high tolerance to complex water matrixes and excellent degradation performance for other polycyclic aromatic hydrocarbons and chlorinated olefins. In addition, the naphthalene degradation pathways and the toxicity of detected intermediates were investigated. This research revealed the mechanism of nano-calcium peroxide activation by pyrite coupled with citric acid and demonstrated the great application potential of this system in the treatment of polluted groundwater.

Insight into the Inclusion Complexation of Fluconazole with Sulfonatocalix[4]naphthalene in Aqueous Solution, Solid-State, and Its Antimycotic Activity.

The study aims to assess the interaction between fluconazole and sulfonatocalix[4]naphthalene towards enhancing its dissolution performance and antimycotic activity. A solubility study was carried out at different pH conditions, and the results revealed the formation of a 1:1 molar ratio fluconazole-sulfonatocalix[4]naphthalene inclusion complex with an AL type phase solubility diagrams. The solid powder systems of fluconazole-sulfonatocalix[4]naphthalene were prepared using kneaded and co-evaporation techniques and physical mixtures. DCS, PXRD, TGA-DTG, FT-IR, and in vitro dissolution performance characterize the prepared systems. According to physicochemical characterization, the co-evaporation approach produces an amorphous inclusion complex of the drug inside the cavity of sulfonatocalix[4]naphthalene. The co-evaporate product significantly increased the drug dissolution rate up to 93 ± 1.77% within 10 min, unlike other prepared solid powders. The antimycotic activity showed an increase substantially (p ≤ 0.05, t-test) antimycotic activity of fluconazole co-evaporate mixture with sulfonatocalix[4]naphthalene compared with fluconazole alone against clinical strains of Candida albicans and Candida glabrata. In conclusion, sulfonatocalix[4]naphthalene could be considered an efficient complexing agent for fluconazole to enhance its aqueous solubility, dissolution performance, and antimycotic activity.

In Situ Modification of Activated Carbons by Oleic Acid under Microwave Heating to Improve Adsorptive Removal of Naphthalene in Aqueous Solutions

This study aimed to improve the adsorption capacity of activated carbon (AC) towards naphthalene (NAP) in aqueous solutions. Starch-based AC (SAC) and pulverized coal-based AC (PCAC) were prepared in a one-pot procedure by activation with oleic acid and KOH under microwave heating. Brunauer–Emmett–Teller (BET) specific surface areas reached 725.0 and 912.9 m2/g for in situ modified SAC (O-SAC1) and PCAC (O-PCAC1), respectively. π–π bond, H-bond, and hydrophobic effects were directly involved in the NAP adsorption process. Batch adsorption data were well fitted by pseudo-second order kinetics and the Freundlich isotherm model. As compared to ACs prepared with only KOH activation, NAP adsorption capacities of PCAC and SAC prepared by the one-pot method increased by 16.9% and 13.7%, respectively. Influences of varying factors were investigated in column adsorption of NAP using O-SAC1 and O-PCAC1. Based on breakthrough curves analysis, the larger column height (H), lower flow rate (Q0), and lower initial concentration (C0) resulted in the longer breakthrough and exhaustion times in both cases. Specifically, we concluded that O-PCAC1 exhibits better adsorption capacity than O-SAC1 in the given conditions. The optimized operating parameters were 1 cm (H), 1 mL/min (Q0) and 30 mg/L (C0). Finally, column adsorption data could be well fitted by the Thomas model.

Calcium Hydroxide Effect in Degradation of Aqueous Naphthalene: Nucleophilic Substitution of Hydrogen at the C(sp2)–H Bond

The degradation of naphthalene in aqueous solutions containing submerged calcium peroxide-based and calcium hydroxide pellets was examined by using UV–vis and IR spectroscopy and mass spectrometry. The observed products are one-ring and fused rings quinoid and aromatic compounds containing OH and C(H)O groups. Their formation is explained in terms of a Ca2+ cation–π interaction and a nucleophilic OH– attack at the aromatic ring ensued by a departure of H– anion. Such process has not been so far observed in aqueous phase. Its recognition may become a challenge for further studies on applications of alkaline substances in remediation of wastewater and soil contaminated with polycyclic hydrocarbons.

Adsorption of Naphthalene on Modified Zeolite from Aqueous Solution

In this study, the modified zeolite with certain hydrophobicity was prepared by modifying natural zeolite by the silane coupling agents such as vinyltrimethoxysilane (VTMO), trimethoxysilane (TMS) and trimethylchlorosilane (TMCS). The modified zeolite has a higher hydrophobicity and adsorption capacity than natural zeolite while ensuring the advantages of natural zeolite, which is more conducive to the adsorption of organic pollutants from aqueous solution. The adsorption experiment on naphthalene in aqueous solution shows that the modified zeolite has a stronger adsorption capacity. In the adsorption thermodynamics experiment, the isothermal adsorption models such as Freundlich and Langmuir can better describe the adsorption of naphthalene on modified zeolite, but the isothermal adsorption model Freundlich has a higher correlation. At 303K, the static adsorption capacity is 339μg/g. The kinetic analysis shows that the adsorption of naphthalene on modified zeolite conforms to the quasi-second order kinetic model.

Optimal experimental designs for estimating Henry's law constants via the method of phase ratio variation

When measuring Henry's law constants (kH) using the phase ratio variation (PRV) method via headspace gas chromatography (GC), the value of kH of the compound under investigation is calculated from the ratio of the slope to the intercept of a linear regression of the inverse GC response versus the ratio of gas to liquid volumes of a series of vials drawn from the same parent solution. Thus, an experimenter collects measurements consisting of the independent variable (the gas/liquid volume ratio) and dependent variable (the GC−1 peak area). A review of the literature found that the common design is a simple uniform spacing of liquid volumes. We present an optimal experimental design which estimates kH with minimum error and provides multiple means for building confidence intervals for such estimates. We illustrate performance improvements of our design with an example measuring the kH for Naphthalene in aqueous solution as well as simulations on previous studies. Our designs are most applicable after a trial run defines the linear GC response and the linear phase ratio to the GC−1 region (where the PRV method is suitable) after which a practitioner can collect measurements in bulk. The designs can be easily computed using our open source software optDesignSlopeInt, an R package on CRAN.

Gamma radiolytic degradation of naphthalene in aqueous solution

Abstract The decomposition of naphthalene in aqueous solution was studied using gamma irradiation combined with both H2O2 and TiO2 nanoparticles. Gamma irradiation led to a complete degradation of naphthalene and a partial mineralization. With initial concentration of 5–32 mg/L, more than 98% of naphthalene was removed and TOC reduction reached 28–31% at an absorbed dose of 3.0 kGy. The degradation of naphthalene was faster at neutral pH and the initial degradation rate increased with increasing the initial concentration of naphthalene. Addition of H2O2 and TiO2 nanoparticles all enhanced the degradation and mineralization of naphthalene. TOC removal efficiency increased from 28% (irradiation alone) to 35% with addition of H2O2 (40 mg/L), and to 48% with addition of TiO2 (0.8 g/L). The degradation of naphthalene in aqueous solution by gamma irradiation was mainly through the oxidation by ·OH radicals. The intermediate naphthol and carboxylic acids such as formic acid and oxalic acid were identified by LC–MS and IC.

Selective Adsorption of Naphthalene in Aqueous Solution on Mesoporous Carbon Functionalized by Task-specific Ionic Liquid

As a large group of persistent organic pollutants, polycyclic aromatic hydrocarbons (PAHs) commonly coexist with chlorinated organic compounds in industrial wastewater. Preferential adsorption of PAHs from wastewater and final effluent is essential in pretreatment processes. In this study, a novel nitrogen-doped mesoporous carbon (NMC) with high surface area (2130 m2/g) and bimodal pore size distribution (∼2 and ∼9.4 nm) was synthesized via a solvent evaporation induced self-assembly process using task-specific ionic liquid (TSIL) as the nitrogen source. The selective adsorption of naphthalene (NAP) with pentachlorophenol (PCP) on NMC in aqueous solution was investigated compared with conventional ordered mesoporous carbon (OMC). Kinetic studies revealed that the NAP adsorption process achieved equilibrium within 5 min and followed a pseudo-second-order rate equation. The adsorption capacity of NMC for NAP was 3.2 mmol/g, which was about 13 times that for PCP at pH 10 in a bi-solute system. The equilibriu...

Catalytic Sorption of (Chloro)Benzene and Naphthalene in Aqueous Solutions by Granular Activated Carbon Supported Bimetallic Iron and Palladium Nanoparticles

Adsorption of benzene, chlorobenzene, and naphthalene on commercially available granular activated carbon (GAC) and bimetallic nanoparticle (Fe/Pd) loaded GAC was investigated for the potential use in active capping of contaminated sediments. Freundlich and Langmuir linearizations were both applied to this data, and it was found that the Freundlich model most closely fits the experimental data. Based on Freundlich parameters, the effective partitioning coefficients (L kg−1) taking into account and were calculated to be and for benzene and chlorobenzene, respectively, on GAC. In addition, effective partitioning coefficients (L kg−1) were 650, 5640, and for benzene, chlorobenzene, and naphthalene, respectively, on Fe/Pd/GAC. Values of were 6.11, 7.11, and 7.54 for benzene, chlorobenzene, and naphthalene, respectively, for GAC and 4.53, 5.47, and 5.22, respectively, for Fe/Pd/GAC.

A novel hypercrosslinked polymeric adsorbent modified by phenolic hydroxyl group of 2-naphthol with bromoethane as crosslinking reagent

A novel hypercrosslinked polymeric adsorbent of LM-6 was prepared by post-crosslinking reaction with 2-naphthol. Bromoethane was used as crosslinking reagent to substitute poisonous organic compound of chloromethyl methylether. Selective adsorption on LM-6 in mixture solution which consisting of 2-naphthol and naphthalene shows that the adsorption of 2-naphthol and naphthalene in aqueous solution are mainly pushed by physical interaction. The adsorption of 2-naphthol is also partly pushed by chemical interaction. The adsorptive enthalpy illuminates that there exists hydrogen-bonding between 2-naphthol and LM-6. Owning to hydrogen-bonding, the adsorption capacity of 2-naphthol on LM-6 is markedly higher than that of naphthalene. In aqueous solution, the adsorption process contains two steps: desorption of water first and then adsorption of solute. Dynamic analysis shows that adsorption capacity of 2-naphthol is higher than that of naphthalene. The adsorption rate is mainly affected by the diffusion of liquid membrane, the diffusion inside particulate or coordinated effect.

Spatial hydration maps and dynamics of naphthalene in ambient and supercritical water

The hydration structures and dynamics of naphthalene in aqueous solution are examined using molecular-dynamics simulations. The simulations are performed at several state points along the coexistence curve of water up to the critical point, and above the critical point with the density fixed at 0.3 g/cm(3). Spatial maps of local atomic pair-density are presented which show a detailed picture of the hydration shell around a bicyclic aromatic structure. The self-diffusion coefficient of naphthalene is also calculated. It is shown that water molecules tend to form pi-type complexes with the two aromatic regions of naphthalene, where water acts as the H-bond donor. At ambient conditions, the hydration shell of naphthalene is comprised, on average, of about 39 water molecules. Within this shell, two water molecules can be identified as pi-coordinating, forming close to one H-bond to the aromatic rings. With increasing temperature, the hydration of naphthalene changes dramatically, leading to the disappearance of the pi-coordination near the critical point.

Electroremediation of Naphthalene in Aqueous Solution Using Alternating and Direct Currents

The key objectives of this study were to evaluate the use of an alternating current (AC) for the degradation of naphthalene in spiked aqueous solutions and to investigate the effect of current density on the degradation rates of naphthalene. Direct current (DC) was also used to compare the rates of degradation. Sodium chloride (NaCl) and anhydrous sodium sulfate (Na2SO4) were used as the supporting electrolytes. Degradation rates and byproducts formed were investigated when DC and AC were separately passed through naphthalene solutions. A square wave AC, having a frequency equal to 0.1Hz was used. Naphthalene solutions having an initial concentration of about 20mg∕L(∼0.15mM) were subjected to an AC peak current density and DC density of 6mA∕cm2, using NaCl as the supporting electrolyte. An approximate 65% reduction in the concentration of naphthalene was observed after a period of 48 h when DC was applied. Degradation was almost 100% when the AC was applied during the 48-h period. The effect of current density on the electrochemical degradation rate of naphthalene in aqueous solution was also investigated at alternating and direct current densities of 1, 3, and 6mA∕cm2 using Na2SO4 as the supporting electrolyte. AC peak current densities of 1, 3, and 6mA∕cm2 resulted in overall conversions of 77, 87, and 95%, respectively, of naphthalene in solution. The corresponding values for DC application were 95% for all current densities while the initial degradation rates were greater at higher DC densities. Based on the degradation products formed, hydroxylation is believed to be the key mechanism for the degradation of naphthalene.

Nitration and Photonitration of Naphthalene in Aqueous Systems

The nitration of naphthalene was studied in aqueous solution to gain insight into the processes leading to the nitration of aromatic compounds in atmospheric hydrometeors. Reactants used were nitric acid, nitrogen dioxide and peroxynitrous acid in the dark, nitrate, and nitrite/nitrous acid under illumination. Naphthalene nitration can lead to two possible isomers, 1- and 2-nitronaphthalene. The former nitrocompound preferentially forms upon electrophilic processes and in the presence of nitrogen dioxide. Electrophilic nitration of naphthalene takes place in the presence of concentrated nitric acid, but nitration with nitric acid and oxidants (charge-transfer nitration) occurs under much milder conditions than with nitric acid alone. Charge-transfer nitration may have some environmental significance in particular cases, e.g. in acidic aerosols in the presence of HNO3 and oxidants. Nitrogen dioxide is thought to have a role in PAH nitration in the Antarctic particulate matter. In previous papers we have found that nitration induced by peroxynitrous acid, HOONO, can follow two pathways, the former electrophilic (leading for instance to the formation of nitrophenols from phenol) and the latter probably involving HOONO itself (accounting for the formation of nitrobenzene from benzene). In the case of naphthalene and HOONO the electrophilic pathway mainly leads to 1-nitronaphthalene, while the other one preferentially yields 2-nitronaphthalene. The nitration of naphthalene in the presence of nitrite/nitrous acid under irradiation leads to both nitroisomers in similar ratios, and the process is not inhibited by hydroxyl scavengers. This excludes nitrogen dioxide as reactive species for nitration and marks a difference with phenol photonitration and a similarity with the behavior of benzene under comparable conditions. Nitrite photochemistry (and nitrite-induced photonitration as well) is expected to be relevant in fog and cloudwater in polluted areas. An important difference with the gas-phase nitration is that the radicals OH and NO3 are unlikely to play a relevant role in the nitration of naphthalene in aqueous solution.

Natural Sunlight Induced Photooxidation of Naphthalene in Aqueous Solution

There is surprisingly little data on the photooxidation of polycyclic aromatic hydrocarbons (PAHs) under environmentally relevant lighting conditions. The aqueous photooxidation reactions of naphthalene (the simplest and most water soluble PAH) were investigated using natural sunlight as a light source.Six of the major reaction products were identified, including 1-naphthol, coumarin, and two hydroxyquinones. The reactionproducts were consistent with initial [2,2] or [2,4] photocycloaddition reactions, with subsequent oxidations and/or rearrangements. The oxidation reactions in aqueous phase favoredproducts different from those observed in atmospheric oxidation reactions. However, similar photoproducts were observed withtitanium catalysts or in the presence of hydrogen peroxide. Theproducts from aqueous photooxidation were also similar to the products resulting from naphthalene metabolism. The observedphotooxidation products were generated by mechanisms that areexpected to occur with other PAHs as well, and thus naphthaleneoxidation provides a model for possible photoreactions of largerPAHs.

Investigations of Naphthalene Solubilization in Aqueous Solutions of Ethylene Oxide-b-Propylene Oxide-b-Ethylene Oxide Copolymers

The enhanced apparent solubility of naphthalene in aqueous solutions of several ABA block copolymeric surfactants has been measured using HPLC. The surfactants investigated combine, within their structure, a block of propylene oxide (PO) (the hydrophobic B block) sandwiched between two blocks of ethylene oxide (EO) (the hydrophilic A blocks). This commercially produced family of surfactants encompass a variety of materials which differ from each other in terms of block sizes and thus in terms of the balance of hydrophobic and hydrophilic forces. It is this balance which controls the ability of the surfactants to effect particular solubility enhancements. Substantial increases in solubility arise from the incorporation of naphthalene into block copolymer micelles. However the experimental data also point to solubility enhancements arising from naphthalene−surfactant interactions at surfactant concentrations below the critical micelle concentration (cmc). The apparent equilibrium constantdescribing the solu...

Microbial sensors for naphthalene using Sphingomonas sp. B1 or Pseudomonas fluorescens WW4

Amperometric biosensors for naphthalene were developed using either immobilized Sphingomonas sp. B1 or Pseudomonas fluorescens WW4 cells. The microorganisms were immobilized within a polyurethane-based hydrogel, which was used for a microbial biosensor for the first time. Both strains were shown to be equally suited for the quantification of naphthalene in aqueous solutions. The biosensors were tested in a flow-through system and a stirred cell (batch method). In both systems a linear response down to the detection limit was obtained. Measurements in the flow-through system gave sensitivities of up to 1.2 nA mg−1 l−1 and a linear range from 0.03 mg/l to 2.0 mg/l. The response time (t95) was 2 min and the sample throughput six per hour; the repeatability was within ±5 %. With the batch method, sensitivities of between 3 nA mg−1 l−1 and 5 nA mg−1l−1 and a linear range of 0.01–3.0 mg/l were obtained; the response time was between 3 min and 5 min. The sensors reached an operational lifetime of up to 20 days. The sensitivity of both sensors for naphthalene was, in most cases, more than four times higher than for various other substrates.

Oxidation of naphthalene by radiolytically produced [rad]OH radicals

Radiolytically produced OH radicals react with naphthalene in aqueous solution in the presence of ferricyanide mainly to yield 1- and 2-naphthol in a ratio of 2.1:1. Reaction takes place via addition of OH to the naphthalene with a rate constant of 1.2 x 10 10M -1S -1. Because of the low solubility of naphthalene (∼ 2 x 10 -4M) γ-radiolysis studies were carried out at doses of ∼ 10 3 rad, where the naphthols were produced at micromolar concentrations. Analysis was by high-performance liquid chromatography. The initial yields of naphthols from solutions saturated with N 2O and naphthalene total 4.7 molec/100 eV, indicating near to quantitative conversion of the OH adducts to the naphthols by the ferricyanide. The observed product ratio is taken to reflect a two-fold preference for attack of OH at the 1-position as compared with that at the 2-position of naphthalene with only little (<10%) reaction at the 9-position.

Solubilization as a method for studying self-association: Solubility of naphthalene in the bile salt sodium cholate and the complex pattern of its aggregation

AbstractSolubilization of uncharged, slightly soluble solutes is shown to be a useful approach for investigating patterns of self-association. The solubility of naphthalene in aqueous solutions of sodium cholate was determined over the concentration range of 0-0.20 mole/liter at 25°. Bile salts such as sodium cholate have many detergent-like properties and exhibit hydrophobic self-association in aqueous solutions. It has become customary to describe this aggregation using the model of micelle formation. The naphthalene solubility data show that the CMC for sodium cholate is not well defined. Comparison with solubilization in a typical micelle-forming system, sodium decanesulfonate, shows clearly that sodium cholate does not resemble a micelle-forming system. Further examination of the solubility data in terms of mutual association of naphthalene with aggregate species shows that the self-association of sodium cholate is not consistent with the formation of (a) only large micelles containing 10 or more monomers, (b) only dimers, (c) dimers and large micelles, and (d) any unique oligomer or multimer. A complex pattern of association, including the formation of dimers and one or more higher oligomers, is indicated.