Naphthalene Research Articles

Density Functional Theory Modeling of Solid-State Nuclear Magnetic Resonances for Polycyclic Aromatic Hydrocarbons

We acknowledge funding from C. Madrid (Grant S2013/MIT-2753), MINECO (Grants MAT2014-54231, MAT2016-78625-C2-2P, MAT2016-78362-C4-2-R, and FIS2015-6422-C2-1-P), EU (Grant ERC-2013-SYG-610256 NANOCOSMOS), Generalitat Valenciana (Grant PROMETEO/2017/139); the University of Alicante and computing resources from CTI-CSIC.

Degradation Characteristics and Metabolic Pathway of a Pyrene-Degrading Pseudomonas aeruginosa Strain

Polycyclic aromatic hydrocarbons (PAHs) pose a potential threat to ecosystems due to their mutagenic, carcinogenic, and teratogenic effects. Microbial degradation has been suggested as the best way to remove PAHs from contaminated environments. Screening of bacterial strains capable of efficiently degrading PAHs is the key to the bio-remediation technique. With the method of enrichment culture, the bacterial strain LX2, which can use pyrene as the sole carbon source, was isolated from sludge contaminated with PAHs. The strain was identified as Pseudomonas aeruginosa (Pseudomonas sp. LX2) according to the results of the analyses of its morphology, physiology, and phylogeny of its 16S rDNA sequence. The degradation rate of pyrene by Pseudomonas sp. LX2 was 32.1% after 21 days of cultivation at an initial pyrene concentration of 50 mg·L-1. Pyrene, 4,5-dihydro-, 2'-Hydroxypropiophenone, Phenol, and Protocatechuate were identified as the major metabolites by GC/MS analysis. Based on the identified metabolites, it was concluded that pyrene was degraded via two different routes by Pseudomonas aeruginosa, namely the 'naphthalene' and the 'phthalic acid' routes.

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.

Demonstration of the contributions of pulmonary CYPs to naphthalene‐induced airway toxicity using lung‐Cpr‐null mice

Naphthalene (NA) is an omnipresent air pollutant and respiratory toxicant. NA induces cytotoxicity in airways following bioactivation by CYP (P450) enzymes. Previous studies suggested that liver and lung are both capable of bioactivating NA in vitro and in vivo. However, direct evidence for a specific role of pulmonary P450 enzymes in mediating NA‐induced airway toxicity, particularly upon exposure to NA via the systemic route, is still lacking.The aim of this study was to examine the specific contribution of pulmonary CYPs to airway toxicity of NA using a lung‐Cpr‐null mouse. We predicted that lung epithelial cells that lack Cpr expression, which would have little microsomal P450 activity, would be resistant to NA‐induced cytotoxicity. Cre‐mediated deletion of Cpr in the lung‐Cpr‐null mouse occurred in a substantial proportion of the Club cells, which, before undergoing Cpr deletion, had high ability to bioactivate NA. Under the conditions used, doxycycline‐induced deletion of Cpr occurred in 66% of Club cells in proximal airways and 86% of Club cells in distal airways, based on the results of a dual immunofluorescence study. Levels of NA and NA‐GSH (a biomarker of NA bioactivation) were similar in the plasma of lung‐Cpr‐null mice and their control littermates after administration of a single bolus dose of NA (200 mg/kg). Histological examination of airways revealed that NA‐induced damage of epithelial cells is focal and mild in lung‐Cpr‐null mice compared to severe exfoliation of epithelial cells in most airways in NA‐treated control mice. Moreover, the number of proliferating (BrdU‐positive) airway epithelial cells was 4‐fold lower in NA‐treated lung‐Cpr‐null mice than in NA‐treated control littermates.These results confirm that CYPs in the lung can mediate NA‐induced airway epithelial damage in vivo.Support or Funding Informationsupported in part by NIH grant ES020867This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Removal and biodegradation of different petroleum hydrocarbons using the filamentous fungus Aspergillus sp. RFC-1.

Petroleum pollution inevitably occurs at any stage of oil production and exerts a negative impact on the environment. Some microorganisms can degrade petroleum hydrocarbons (PHs). Polluted sludge of Rumaila oil field was use to isolate the highly efficient hydrocarbon‐degrading fungal strain. Aspergillus sp. RFC‐1 was obtained and its degradation ability for petroleum hydrocarbons was evaluated through surface adsorption, cell uptake, hydrophobicity, surface tension, biosurfactant production, and emulsification activity. In addition, the degradation mechanism was investigated. The results indicated the strain RFC‐1 showed high removal activity for PHs, including biodegradation, adsorption, and emulsifiability. On the day 7 of incubation, the removal efficiencies of crude oil, naphthalene (NAP), phenanthrene (PHE), and pyrene (PYR) reached 60.3%, 97.4%, 84.9%, and 90.7%, respectively. Biodegradation efficiencies of crude oil, NAP, PHE, and PYR were 51.8%, 84.6%, 50.3%, and 55.1%, respectively. Surface adsorption and cell absorption by live mycelial pellets followed a decreasing order: PYR ≥ PHE > NAP > crude oil. Adsorption by heat‐killed mycelial pellets increased within 40 and 10 min for crude oil and PAHs, respectively, and remained constant thereafter. Effects of cell surface hydrophobicity, surface tension, and emulsification index were discussed. Intra‐ and extracellular enzymes of strain RFC‐1 played important roles in PHs degradation. The strain RFC‐1 is a prospective strain for removing PHs from aqueous environments.

Kinetic Assessment of the Simultaneous Hydrodesulfurization of Dibenzothiophene and the Hydrogenation of Diverse Polyaromatic Structures

The elimination of sulfur from fossil fuels via hydrodesulfurization (HDS) is paramount to produce cleaner fuels. Ultradeep HDS refers to reducing sulfur in fuels below the 10 ppm level. Nevertheless, under such conditions, dibenzothiophenes (DBTs) are to be desulfurized in the presence of highly complex aromatic structures that possibly exert inhibitory effects. Therefore, this contribution presents a kinetic study of the inhibition effect of diverse aromatic structures: naphthalene (NP), fluorene (FL), and phenanthrene (PHE), on the HDS of dibenzothiophene over a sulfided NiMo/γ-Al2O3 catalyst. Kinetic modeling was based on the Langmuir–Hinshelwood–Hougen–Watson (LHHW) formalism and was submitted to regression analyses with the reparametrized form of the Arrhenius and van’t Hoff equations. Before addressing inhibition effects, the kinetics of the HDS of DBT was revisited. In this sense, observations were better fitted when considering that the two parallel pathways for the HDS of DBT, i.e., the so-calle...

Three-dimensional ionic liquid-ferrite functionalized graphene oxide nanocomposite for pipette-tip solid phase extraction of 16 polycyclic aromatic hydrocarbons in human blood sample

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitously found in the environment and have been proved to be prospectively associated with the risk of cancer. In this study, a simple method based on pipette-tip solid phase extraction (PT-SPE) and gas chromatography-mass spectrometry (GC–MS) has been firstly developed for the determination of 16 PAHs in human whole blood. Three-dimensional ionic liquid-ferrite functionalized graphene oxide nanocomposite (3D-IL-Fe3O4-GO) was used as sorbent in PT-SPE. Compared with conventional SPE method, the PT-SPE method was solvent-saving (1.0 mL), reusable (at least 10 times) and required less blood sample (200 μL). Affecting parameters on extraction efficiency were investigated and optimized. Under the optimized conditions, a good linearity was obtained and the recoveries of 16 PAHs at three spiked levels ranged from 85.0% to 115%. The limits of quantification (LOQs) were in the range of 0.007-0.013 μg/L. Furthermore, the developed method was successfully applied to the analysis of 16 PAHs in 14 human blood samples. The results showed that the predominant PAHs in human whole blood was low-molecular-weight PAHs, with the rank order phenanthrene (PHE)> naphthalene (NAP)> fluorene (FLU)> fluoranthene (FLT)> pyrene (PYR). Because of its simplicity, accuracy and reliability, the PT-SPE method combined with GC–MS demonstrated the applicability for clinical analysis and provided more information for PAHs exposure studies.

Emission characteristics of polycyclic aromatic hydrocarbons from pyrolytic processing during dismantling of electronic wastes

Two typical types of electronic waste (E-waste) were selected to investigate the emission characteristics of polycyclic aromatic hydrocarbons (PAHs) during pyrolytic processing, including emission factor, compositional profile, size distribution and gas-particle partitioning. The mean emission factors (EFs) of total PAHs were measured to be 2.77 ± 1.41 μg/g and 23.65 ± 14.52 μg/g for printed wiring boards and plastic casings, respectively, lower than those for coal combustion and biomass burning. Low molecular weight species were predominant in exhaust fumes, with overwhelming amounts of naphthalene (NAP) and phenanthrene (PHE) in the gaseous phase and particulate phase, respectively. The particle-size distribution exhibited the largest enrichment of total PAHs in finer particles less than 2.1 μm. Similarly, the distributions of individual species were dominated by finer particles. Most freshly emitted PAHs were liable to exist in particulate phase relative to gaseous phase. Based on the benzo[a]pyrene equivalent carcinogenic power, PAHs in particulate phase may have much stronger toxicity compared with those present in gaseous phase. The gas-particle partitioning behaviors of freshly emitted PAHs from pyrolytic processing of E-wastes were mainly regulated by absorption rather than adsorption, and the gas-particle partitioning did not reach equilibrium.

Four-dimensional data coupled to alternating weighted residue constraint quadrilinear decomposition model applied to environmental analysis: Determination of polycyclic aromatic hydrocarbons

Qualitative and quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) was carried out by three-dimensional fluorescence spectroscopy combining with Alternating Weighted Residue Constraint Quadrilinear Decomposition (AWRCQLD). The experimental subjects were acenaphthene (ANA) and naphthalene (NAP). Firstly, in order to solve the redundant information of the three-dimensional fluorescence spectral data, the wavelet transform was used to compress data in preprocessing. Then, the four-dimensional data was constructed by using the excitation-emission fluorescence spectra of different concentration PAHs. The sample data was obtained from three solvents that are methanol, ethanol and Ultra-pure water. The four-dimensional spectral data was analyzed by AWRCQLD, then the recovery rate of PAHs was obtained from the three solvents and compared respectively. On one hand, the results showed that PAHs can be measured more accurately by the high-order data, and the recovery rate was higher. On the other hand, the results presented that AWRCQLD can better reflect the superiority of four-dimensional algorithm than the second-order calibration and other third-order calibration algorithms. The recovery rate of ANA was 96.5%~103.3% and the root mean square error of prediction was 0.04μgL−1. The recovery rate of NAP was 96.7%~115.7% and the root mean square error of prediction was 0.06μgL−1.

Adsorptive removal of aromatic hydrocarbons from water over metal azolate framework-6-derived carbons

Metal azolate framework-6 (MAF-6) was pyrolyzed at 1000°C to yield MOF-derived carbons (MCs). The obtained MCs were used to eliminate aromatic hydrocarbons, including polyaromatic hydrocarbons (PAHs; e.g., naphthalene (NAP), anthracene (ATC), and pyrene (PRN)) and benzene (BZ) from water via adsorption. The adsorption results over the MCs were compared with that of pristine MAF-6 and commercial activated carbon (AC). MC obtained after 24h (MC-24) exhibited a remarkable adsorption efficiency compared to that of the other MCs (obtained after different durations), MAF-6, and AC. For example, MC-24 led to adsorptions of NAP around 17 and 2.5 times those of pristine MAF-6 and AC, respectively. Or, the maximum adsorption capacities (Q0) of MAF-6, AC and MC-24 for NAP were 14, 104 and 237mg/g, respectively. Moreover, Q0 values of MC-24 for ATC and PRN were also very high of 284 and 307mg/g, respectively. Based on the properties of PAHs and the hydrophobicity of MC-24, hydrophobic interaction was suggested as the main mechanism for the adsorption of PAHs and BZ. In addition, MC-24 can be recycled by washing with acetone with little loss in performance. Therefore, MC-24 is recommended as a competitive adsorbent for aromatic hydrocarbon removal from water.

Adsorption and anoxic degradation of typical pahs in bohai coastal sediments

This paper aims to disclose the adsorption and anoxic degradation processes of three typical polycyclic aromatic hydrocarbons (PAHs) in the coastal sediments of China’s Bohai Sea region. The PAHs are naphthalene (Nap), phenanthrene (Phe) and pyrene (Pyr). Several sediments samples were collected from Qinhuangdao Port, and subjected to adsorption and biodegradation experiments. Then, pseudo-first-order and pseudo-second-order kinetic models were tested to explain the kinetics of liquid-solid phase adsorption systems. It is discovered that the adsorption of the three PAHs on the coastal sediments matched pseudo- second-order kinetics, revealing that adsorption processes were essentially chemical reactions. In terms of equilibrium adsorption capacity, the three PAHs are ranked as Pyr>Phe>Nap. Next, Freundlich and Langmuir models were employed to fit the experimental data. The fitting results show that the adsorption of Nap, Phe and Pyr on the coastal sediments can be explained as mono-molecular layer adsorption. All the adsorptions of Nap, Phe and Pyr were exothermic reactions. In the anoxic sediments, 93.2% of Nap was removed after 30h, 96.6% of Phe was removed after 7d, and 98.1% of Pyr was removed after 42d. The detected metabolites of Nap were [4,4-dimethyl-2-cyclohexene-1-ol], [1-carboxyl,2-hydroxy, 4-methyl-cyclohexane], the metabolites of Phe were [3-ethoxy ethyl benzoate], [Phthalate (2-methyl propyl) ester] and the metabolites of Pyr were [2- methyl succinic acid, double (2-methyl propyl) ester], [Phthalate (2-methyl propyl) ester], [Phthalic acid butyl ester, 14 alkyl ester]. The findings shed new light on the research of PAHs adsorption and anoxic degradation in coastal sediments.

Study on the Effects of the Types and Addition Time of Chemical Admixtures on Cement Performance

The effects of single admixture and combined admixture of Naphthalene Superplasticizer (NFS), Polycarboxylate Superplasticizer (PCC) and Li2CO3 and the addition time of superplasticizer on the fluidity, strength and adsorption capacity and other properties of cement paste are studied in this paper. NFS and PCC can significantly enhance the fluidity of cement paste; the greater the dosage of chemical admixture, the longer the initial setting time of cement; the suitable dosage of NFS is 0.4% -0.6%; the overall fluidity is the best, when the content of Li2CO3 is 0.01%. The combined admixture of PCC and Li2CO3 has little effect on the fluidity of cement paste. The higher the content of Li2CO3, the larger the adsorption capacity of cement particles to NFS, while the content of Li2CO3 basically does not affect the adsorption capacity of cement to PCC, indicating that Li2CO3 has the auxiliary water reducing effect, which can enhance the fluidity of cement paste. With a combined admixture of NFS and Li2CO3, Li2CO3 will have a great influence on the setting time of cement, and when the content of Li2CO3 is 0.35%, the initial setting time of cement is reduced by about 85.9% and the final setting time is reduced about 82.2%. The cement adsorption capacity of cement drops sharply after adding NFS and PCC 5-10 min after cement hydration. After 10 min, superplasticizer is added, and the declining tendency of cement adsorption capacity gradually becomes gentle. When the content of PCC increases from 0.4% to 0.6% and the content of NFS increases from 0.6% to 1.0%, the electronegativity of the surface of the cement shows an overall increasing trend, but when the superplasticizer is added to the cement 5-10min after hydration, the electronegativity is gradually reduced.

Sorption of ionic and nonionic organic solutes onto giant Miscanthus-derived biochar from methanol-water mixtures

The sorption of naphthalene (NAP) and 1-naphthoic acid (1-NAPA) onto giant Miscanthus–derived biochar was investigated in methanol volume fractions (fc) of 0–0.6 as a function of ionic composition (5mM CaCl2 and 10mM KCl) and liquid pH (2 and 7). The sorption onto biochar was nonlinear with 0.42≤N≤0.95; thus, a concentration-specific sorption constant (Km) was compared. The Km log linearly decreased with increasing fc, except for 1-NAPA from a CaCl2 mixture at pH7. Isotherm data was fitted with a cosolvency sorption model through which the slope (ασ) of the inverse log linear Km-fc plot and empirical constant (α) were obtained. NAP sorption was well described by the cosolvency model with the α value being 0.41–0.53, indicating a methanol–biochar interaction favoring more sorption than the cosolvency based prediction. In particular, the slope (ασ) of 1-NAPA was lower than that of NAP, indicating less reduction of 1-NAPA sorption (i.e., lower α value) by methanol. In comparison with other sorbents, the α value was approximately intermediate between a humic substance and kaolinite clay. An analysis of FT-IR spectra suggested the transformation of O-containing functional groups by methanol, which will subsequently boost the π–π interaction between an organic solute and biochar. Moreover, Ca2+-induced sorption between anionic 1-NAPA and a negatively charged biochar surface was also fortified in the methanol mixture. The results revealed unexplored cosolvent effects on organic solute sorption onto biochar and identified the hydrophobic and hydrophilic sorption moieties of biochar as affected by the cosolvent.

Effects of Medium Compositions and Plant Growth Regulators on in vitro Organogenesis in Cultured Explants of Platycodon grandiflorum Species

Platycodon grandiflorum (Bell flower) is an important plant that has traditionally been used as herbal medicine for the treatment of cough, phlegm, sore throats, lung abscesses, chest pains, dysuria, and dysentery. The present study was initiated to investigate the feasibility of inducing shoot and root organogenesis in cultured explants of P. grandiflorum in a range of culture media and through use of various plant growth regulators (PGRs). The plantlets (Stem containing one node) were isolated and cultured on different concentrations of Murashige and Skoog (MS) medium supplemented with PGRs. We found that proliferation and elongation of shoots and roots could be achieved on ¼ MS for P. grandiflorum with wild and green petals and on ⅛ MS for P. grandiflorum with double petals. The highest levels of development and elongation of adventitious shoots and roots were observed when petal explants were cultured on ¼ MS (pH 3.8) supplemented with 5% sucrose. Increasing the agar concentration reduced shoot growth and rooting potential; nevertheless, the highest number of shoots and roots was observed on 0.6% agar. In the case of growth regulators, ¼ MS supplemented with 1 mg L-1 6-benzylaminopurine (BA) was found to be best for shooting, although higher concentrations of BA tended to reduce shoot and root elongation. The highest number of shoots was achieved on 0.5 mg ․ L-1 thidiazuron (TDZ) from double petal explants grown on ⅛ MS. However, root and shoot elongation were found to decrease when TDZ concentrations were increased. Low concentrations of kinetin, naphthalene acetic acid, indole acetic acid, and 3-indole butyric acid induced shoot and root proliferation and elongation. Taken together, our study showed that low concentrations of PGRs induced the greatest root formation and elongation, showing that the optimal concentration of PGRs for shoot proliferation was species-dependent.

Co-contaminant effects on ofloxacin adsorption onto activated carbon, graphite, and humic acid.

Given their voluminous application, significant amounts of fluoroquinolones are discharged into the environment through wastewater effluent. Adsorption has been shown to be a critical process controlling the environmental behaviors of fluoroquinolones. Competition between ofloxacin (OFL) and naphthalene (NAP)/bisphenol A (BPA) and their adsorption on activated carbon (AC), graphite (GP), and humic acid (HA) were investigated. The suppressed adsorption of OFL was observed on AC and GP, but not on HA, by NAP or BPA. Moreover, for AC, the competition by NAP was slightly stronger than that by BPA. However, for GP, the competition with BPA was higher than that with NAP. These observations indicate that competitive adsorption of OFL with respect to NAP/BPA depends on the degree of overlap of adsorption sites, as interpreted by the following: (i) AC can provide overlapping adsorption sites for OFL, BPA, and NAP, which include non-specific adsorption sites, such as hydrophobic sites, π-π interactions, and micropore filling; (ii) π-π interactions and hydrogen bonding might be responsible for the strong competitive adsorption between BPA and OFL on GP; and (iii) OFL adsorbs on HA through specific adsorption force-electrostatic attraction, with which NAP and BPA cannot compete.

Single-cell gene variation analysis method for single gland.

Single-cell analysis of heterogeneity has become the cutting-edge technology for profound understandings of relationships between cell populations. At present, common methods used in single cellular genomic research are mainly microfluidic technologies (Fluidigm) or based on microwells, both requiring a uniform size of cells at the entrance. However, the size of cells in specific tissues can vary from type to type. To address this issue, we need to establish a method to identify genomic features of individual cells of different sizes. In this paper, we developed a robust method in the analysis of single cellular genomic mutations among gastric tissues. Briefly, the single gastric gland was isolated from the whole tissue, and further enzymatically digested into single cells of various sizes by trypsin. These single cells were then spread on the polyethylene naphthalene slides and selected by the laser microdissection method. Whole genome amplification (WGA) and capillary electrophoresis were performed subsequently to detect single cell microsatellite. This method enabled us to detect the existence of microsatellite instability (MSI) of each single cell within the intestinal metaplasia, and to carry out a flexible and fine analysis of single cells with different sizes in tissues and glands. This reliable and practical method is well performed in both low and high-throughput genome analysis when combined with cell labeling methods, thus providing a novel and highly flexible way to study tissue heterogeneity on the single cell scale.

Adsorption and coadsorption mechanisms of Cr(VI) and organic contaminants on H3PO4 treated biochar

The study of simultaneous removal of heavy metals and organic contaminants has practical applications due to the coexistence of complex pollutants in the wastewater or soil. In this work, biochar was prepared to study the removal efficiencies of Cr(VI), naphthalene (NAP) and bisphenol A (BPA) in the single or mixed systems. H3PO4-treated biochar presented a much higher adsorption capacity of the pollutants than the untreated biochar and also showed a high resistance to coexisting salts. The maximum adsorption capacities for Cr(VI) and BPA were 116.28 mg g−1 and 476.19 mg g−1, respectively. Coadsorption experiments revealed that the presence of organic pollutants caused a limited decrease (∼10%) of removal efficiency of Cr(VI) and no further decrease was observed with higher concentrations of organic pollutants, while the presence of Cr(VI) had little impact on the removal of NAP. Infrared spectra and molecular simulation demonstrated that Cr(VI) was mainly adsorbed on the biochar via chemical complexation, while the organic pollutants through π-π interaction. Unexpectedly, the addition of Cr(VI) increased the removal efficiency of BPA, probably due to the increased H-bond interactions between BPA and the biochar through bridge bonds of oxygenic groups from CrO42−.

Highly efficient capture of naphthalene by nonionic surfactants in hydrogel capsules

The impregnation of Triton X-100 (TX100) in chitosan capsules (TCC) via an anionic surfactant gelation method was investigated for the sorption of naphthalene (NAP) from aqueous solutions. Impregnation with TX100 enhanced NAP sorption at all tested concentrations of TX100, ranging from 0.1 to 10g/l. The highest NAP sorption capacity (68.7mg/g) was obtained at 2g/l of TX100, a capacity 5.1-fold higher than that of chitosan capsules without TX100 impregnation (CC) (13.4mg/g). The highest molar sorption ratio of capsule (MSRC) was 12.23mol NAP/mol TX100 at 0.1g/l, which was much higher than the MSRB for beads (0.70) and the MSRW for the aqueous phase (0.11). Thus, when a nonionic surfactant is present in a hydrogel capsule, the ability of the surfactant to solubilize organic chemicals can be significantly increased compared to the surfactant in water or in hydrogel beads.

Functionalization of Graphene Oxide with 9-aminoanthracene for the Adsorptive Removal of Persistent Aromatic Pollutants from Aqueous Solution.

A novel modified graphene oxide nanocomposite was fabricated via a facial procedure, aiming to removal of the aromatic pollutants from aqueous solution. The graphene oxide (GO) was functionalized with 9-aminoanthracene and produced graphene oxide-9-aminoanthracene (GO-9-AA). FTIR, XRD, TGA, TEM and Raman spectroscopy techniques were used for characterization of the adsorbents. Adsorption of naphthalene (NAP), acenaphthylene (ACN), and phenanthrene (PHN) as a model of polycyclic aromatic hydrocarbons (PAHs) was investigated by GO-9-AA. The adsorbent showed excellent removal efficiency towards PAHs from aqueous solution. Equilibrium data of the adsorption process were successfully fitted with Freundlich model from single solute system, and the maximum adsorption capacities followed the order of NAP > ACN >PHN. The kinetic analysis revealed that the overall adsorption process was fast and successfully fitted with the pseudo-second-order kinetic model. The anthracene ring makes GO-9-AA π-electron rich, thus facilitating π-π EDA interaction between NAP, ACN and PHN with GO-9-AA.

Identifying structural characteristics of humic acid to static and dynamic fluorescence quenching of phenanthrene, 9-phenanthrol, and naphthalene

Fluorescence quenching is a sensitive and fast method to quantify the interactions between a fluorescent organic contaminant and a quencher, such as dissolved organic matter (DOM). Dynamic fluorescence quenching is resulted from molecular collision, not the real binding, and thus it complicates the binding data interpretation. On the other hand, static fluorescence quenching occurs for fluorescent contaminants of ground states, which decreases the concentration of freely dissolved contaminants. However, how a particular structure in DOM contributes to the static and dynamic fluorescence quenching of a fluorescent contaminant is still unclear, which has greatly hindered the application of fluorescence quenching technique. A humic acid (HA) extracted from sediment was chemically modified, i.e., bleaching, acid hydrolysis, and decarboxylation. HAs before and after these modifications were used in fluorescence quenching experiments for phenanthrene (PHE), 9-phenanthrol (PTR) and naphthalene (NAP). Different quenching mechanisms were observed for these chemicals depending on HA properties. For PHE and NAP, aromatic components showed static quenching, while carboxyl groups primarily showed dynamic quenching. Aromatic components and carbohydrates in HAs primarily bound (static quenching) rather than collided (dynamic quenching) with PTR. Carboxyl groups showed interactions with PTR through dynamic quenching only when carboxyl groups were on the benzene ring. Based on the results, we emphasized that dynamic quenching should be carefully excluded in fluorescence quenching studies. This line of study is important to establish a general relationship between DOM properties and static/dynamic quenching contributions.