Initial Naphthalene Concentration Research Articles

Surfactant Coated Silica Nanoparticles as Smart Scavengers for Adsorptive Removal of Naphthalene

This manuscript represents the synthesis of silica nanoparticles modified with four different types of cationic surfactants. The surfactant capped nanoparticles have better control over the size of silica nanoparticles. The as formed as model nanomaterials were used for the removal of naphthalene, a simple white crystalline polycyclic aromatic hydrocarbon (PAH) from aqueous media. The obtained materials were characterized by various microscopic and spectroscopic techniques. The average particle size of nanoparticles was approximately between 50 and 75 nm. The removal kinetic and adsorption studies were also conducted on silica nanoparticles with different contact time, initial concentrations of silica and naphthalene to achieve the optimum adsorption conditions. CPB functionalized nanoparticles have displayed higher removal efficiency of more than 85% as compared to 75 to 80% in case of CTAB, CTAC and CPC functionalized silica nanoparticles. The effects of various parameters like pH, adsorbent doses, naphthalene concentration and addition of salt have also been investigated for better understanding of the removal efficacy of prepared nanoparticles.

Preparation of activated carbon dots from sugarcane bagasse for naphthalene removal from aqueous solutions

ABSTRACTThe synthesis of cheap and environmental friendly adsorbent from residual sugarcane bagasse was done for the removal of naphthalene from aqueous solution. The activated carbon dot was obtained by KOH chemical activation of carbon dots. The characteristics of carbon dots and activated carbon dots were determined using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e., initial pH, initial naphthalene concentration, adsorbent dosage, and contact time. The kinetic data showed better fit to the pseudo-second-order model. The equilibrium data were better fitted to Freundlich and Temkin isotherms.

Influences of operating conditions of surface dielectric barrier discharge on the decomposition of gaseous naphthalene

AbstractPolycyclic aromatic hydrocarbons (PAHs) have received a considerable research interest due to their toxic and carcinogenic effects [1]. Therefore, it is important to remove these compounds before their emission into the ambient air.Nowadays, nonthermal plasma is considered as an emerging technology to remove volatile organic compound (VOC) emissions and other industrial exhausts. The main feature of nonthermal plasma is the generation of reactive species such as O, O3, and OH, which are capable of decomposing organic pollutants at the atmospheric pressure and temperature.In a previous work [2], we developed a new plasma reactor based on surface dielectric barrier discharge (SDBD). The performance of this reactor has been tested for the decomposition of naphthalene at different initial concentrations of naphthalene and different flow rate.Herein, we systematically explore the influences of the operating conditions, in terms of the oxygen content, the relative humidity, the applied voltage and the frequency on the decomposition of naphthalene. Naphthalene, a two-ring compound, was chosen as a model pollutant because it is the most abundant PAH in urban air, where its concentration is often greater than those of all other PAHs combined [3].The main results of this study showed that the decomposition efficiency decreases with the increase of the oxygen content reaching a minimum value at a small content of oxygen and relatively high input power, and then increases at higher oxygen content. In addition, it is found that there is an optimum level of the humidity for the decomposition of the naphthalene in the SDBD, and this value depends on the gas composition. Furthermore, the decomposition efficiency is increased with increasing the applied voltage and frequency due to the increase in the power; which leads to an increase in the reactive species in the reactor with a subsequent increase the decomposition efficiency. The effects of the operating conditions on the characteristics of the SDBD, including the current-voltage waveform, and the power consumed is presented in this work.

Chemical and cellular oxidant production induced by naphthalene secondary organic aerosol (SOA): effect of redox-active metals and photochemical aging

Exposure to air pollution is a leading global health risk. Secondary organic aerosol (SOA) constitute a large portion of ambient particulate matter (PM). In this study, the water-soluble oxidative potential (OP) determined by dithiothreitol (DTT) consumption and intracellular reactive oxygen and nitrogen species (ROS/RNS) production was measured for SOA generated from the photooxidation of naphthalene in the presence of iron sulfate and ammonium sulfate seed particles. The measured intrinsic OP varied for aerosol formed using different initial naphthalene concentrations, however, no trends were observed between OP and bulk aerosol composition or seed type. For all experiments, aerosol generated in the presence of iron-containing seed induced higher ROS/RNS production compared to that formed in the presence of inorganic seed. This effect was primarily attributed to differences in aerosol carbon oxidation state {boldsymbol{(}}{bar{{bf{O}}{bf{S}}}}_{{bf{c}}}{boldsymbol{)}}. In the presence of iron, radical concentrations are elevated via iron redox cycling, resulting in more oxidized species. An exponential trend was also observed between ROS/RNS and {boldsymbol{(}}{bar{{bf{O}}{bf{S}}}}_{{bf{c}}}{boldsymbol{)}} for all naphthalene SOA, regardless of seed type or aerosol formation condition. This may have important implications as aerosol have an atmospheric lifetime of a week, over which {boldsymbol{(}}{bar{{bf{O}}{bf{S}}}}_{{bf{c}}}{boldsymbol{)}} increases due to continued photochemical aging, potentially resulting in more toxic aerosol.

Squamocin, an annonaceous acetogenin, enhances naphthalene degradation mediated by Bacillus atrophaeus CN4

Squamocin belongs to a group of compounds called annonaceous acetogenins. They are secondary products of Annonaceae metabolism and can be isolated from Annona cherimolia seeds. This paper deals with the stimulation of biofilm formation of Bacillus atrophaeus CN4 by employing low squamocin concentrations to increase naphthalene degradation. Bacillus atrophaeus CN4, isolated from contaminated soil, has the ability to degrade naphthalene as the only source of carbon and energy. In the absence of additional carbon sources, the strain removed 69% of the initial concentration of naphthalene (approx. 0.2mmol/l) in the first 12h of incubation. The addition of squamocin in LB medium stimulated Bacillus atrophaeus CN4 biofilm formation and enhanced naphthalene removal. Squamocin (2.5μg/ml) does not affect planktonic growth and therefore, the observed increases are solely due to the stimulation of biofilm formation.

Acid-hydrolyzed agricultural residue: A potential adsorbent for the decontamination of naphthalene from water bodies

Development and application of low-cost and effective adsorbents to remove polycyclic aromatic hydrocarbons from effluents has become a research focus in recent years. We selected reed stem, ginkgo nut shell and hazelnut shell as adsorbents, and used acid hydrolysis as a simple modification technology. The adsorption isotherms of naphthalene to raw and modified adsorbents were controlled by partitioning. The adsorption capability of the hydrolysed hazelnut shell was notably enhanced at a higher level compared with that of other adsorbents. Results showed that the adsorption capacity (17250.42 μg/g) of modified hazelnut shell was observed for an initial naphthalene concentration of 25mg/L, with a contact time of 72 h, adsorbent dosage of 1 g/L and initial pH of 7.0. Furthermore, the regeneration capability of hydrolyzed hazelnut shell indicated that it was a promising adsorbent for naphthalene removal in wastewater treatment.

Rapid adsorptive removal of naphthalene from water using graphene nanoplatelet/MIL-101 (Cr) nanocomposite

The study of the adsorption equilibria of naphthalene onto graphene nanoplatelet supported MIL-101 composite material (GNP/MIL-101) has been conducted. In the experimental context of this study, firstly GNP/MIL-101 was synthesized by applying hydrothermal method and characterized via FTIR, XRD, SEM, TEM and surface area analyses. The effects of GNP/MIL-101 amount, temperature and initial naphthalene concentration on the adsorption process have been investigated. Results show that the maximum removal of naphthalene was obtained as about 93% by 0.075 g GNP/MIL-101 at 298 K. The isothermal data were fitted to linear and non-linear Langmuir, Freundlich, and Temkin adsorption isotherm models and the kinetic data were fitted to Elovich and other kinetic models. Adsorption depended on initial naphthalene concentration at investigated various temperatures (298, 308, 318 K) significantly. The temperature dependence of adsorption process is associated with the changes in several thermodynamic parameters such as standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°).

English

The present research describes the removal of naphthalene from aqueous solution using one of the simplest agricultural wastes, Borassus flabellifer Shell activated carbon (BFS-AC) by adsorption. Adsorption was chosen due to its cost-effectiveness. The effect of operating parameters such as pH, time, initial concentration of naphthalene, BFS-AC dosage and temperature on the percent removal of naphthalene was determined. The optimum conditions obtained were pH of 7, contact time of 12 h for an optimum concentration of 200 mg/L with the addition of 8 g at a temperature optimum at 40°C attaining the maximum percent removal. The adsorption kinetics supported the Freundlich model with R2 value of 0.995 indicating multilayer adsorption. The chemical kinetic studies followed the pseudo second order mechanism. The characterization of BFS-AC was carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD) which showed the enhanced porosity and crystallinity of the adsorbent which was mainly due to the surface modification carried out by chemical addition followed by thermal treatment. The initial and final naphthalene concentration after adding the adsorbent was determined by using gas chromatography-mass spectrometry (GC-MS). The characterization thoroughly suggests the efficacy of B. flabellifer shell to efficiently sequester naphthalene from aqueous solution.  Key words: Naphthalene, Borassus flabellifer, thermo-chemical, activated carbon, adsorption.

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.

Enhanced Immobilization of Polycyclic Aromatic Hydrocarbons in Contaminated Soil Using Forest Wood-Derived Biochar and Activated Carbon under Saturated Conditions, and the Importance of Biochar Particle Size

Leaching behavior of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) can be altered in the presence of organic amendments through enhanced sorption of PAHs to the amended soil. The aim of the present study was to investigate the influence of biochar in two forms (i.e., crushed and pulverized), and granular activated carbon on immobilization and leaching behavior of selected PAHs from contaminated soil into water using the column leaching test. The influence of biochar particle size on leaching behavior of PAHs in biochar-amended soil was also evaluated for the first time in this study. Results showed relatively high initial concentrations of naphthalene, fluorene, and pyrene for unamended column (B1). Strong sorption of all PAHs to soil was observed in this study. At the end of the experiment less than one percent of the solid phase content of the sum of PAHs was released into water in columns B3 and B4. Change in pH due to the application of organic amendments did not affect PAH leaching results. The addition of pulverized biochar and granular activated carbon to soil remarkably reduced mobilization and leaching of the studied PAHs in most cases; however, higher molecular weight PAHs (i.e., pyrene, benzo(b)fluoranthene, and indeno(1,2,3cd)) were mobilized in the presence of crushed biochar in soil. The controlling role of biochar particle size on mobilization and release of PAHs in soil was observed. The application of pulverized biochar and activated carbon increased colloid content of the column effluents while reducing their dissolved organic carbon (DOC) content, suggesting a more significant role of colloid-facilitated transport than DOC-associated transport of PAHs in their leaching from carbon-amended soils, particularly for higher molecular weight PAHs. Based on the obtained results, pulverized biochar and granular activated carbon demonstrated promising and comparable performance in immobilizing PAHs in soil and reducing their leaching from soil into water through enhanced sorption of PAH compounds, which is markedly favorable in terms of soil remediation.

Adsorption of naphthalene from aqueous solution onto fatty acid modified walnut shells.

The removal of polycyclic aromatic hydrocarbons (PAHs) from aqueous solution is challenging to environmental technologists. Agricultural waste is apparently the most attractive materials in removing PAHs because of its abundance, renewability, and economic advantage. The adsorption of PAHs (e.g., naphthalene) onto walnut shell (WNS) and its fatty acid (e.g., capric acid, lauric acid, palmitic acid, and oleic acid)-modified equivalent were investigated in this work to develop low-cost biosorbents for hydrophobic organic compounds. Compared with other modified sorbents, oleic acid graftted walnut shell (OWNS) showed the maximum partition coefficient (4330 ± 8.8 L kg(-1)) because of its lowest polarity and highest aromaticity. The adsorption capacity (7210 μg g(-1)) of OWNS at the temperature of 298 K was observed for an initial naphthalene concentration of 25 mg L(-1) with contact time of 40 h, sorbent dosage of 1 g L(-1), and in neutral condition. Furthermore, the regeneration capability of OWNS implied that it was a promising biosorbent for naphthalene removal.

Adsorptive/photo-catalytic process for naphthalene removal from aqueous media using in-situ nickel doped titanium nanocomposite

The present study investigates the synthesis and characterization of in-situ nickel doped titanium nanocomposite (TiO2/NiO) use as an adsorbent and a photo-catalyst for naphthalene removal from aqueous phase. Nickel-titanium nanocomposites were synthesized by using an in-situ process for the nickel doping and further calcined at 600 °C for 6 h to produce the desired TiO2/NiO nanocomposite, which was then characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and UV—Vis analysis before and after naphthalene removal. The removal of naphthalene was explored with effect of pH, time and initial concentration of naphthalene (2–25 mg/L) in the presence of dark and light phases. Naphthalene removal tests were conducted under both batch and continuous flow conditions. A special column without any channeling problem was successfully designed for the removal of naphthalene by continuous flow process in the presence of visible light source. The removal was maximized at pH 6.5. The maximum amount of naphthalene removed by TiO2/NiO(0.1) nanocomposite in the presence of visible light phase was 322.1 mg/g, which was 2.5 times greater than that of the parent TiO2. The removal of naphthalene obtained during the breakthrough analysis was consistent with the batch equilibrium data.

Biodegradation of naphthalene using Pseudomonas aeruginosa by up flow anoxic-aerobic continuous flow combined bioreactor.

BackgroundNaphthalene is a poly aromatic hydrocarbon (PAH) present in many sediment-water systems. The aim of this study was to evaluate the applicability of an anoxic/aerobic system for the biological treatment of water polluted by naphthalene by Pseudomonas aeruginosa PTCC 1707 to utilize naphthalene. The naphthalene elimination from wastewater was determined in anoxic–aerobic continuous flow combined bioreactor under continuously oxic and anoxic conditions. Experiments were conducted in continues mode, and naphthalene was administered in consecutive spike doses. Then Pseudomonas aeruginosa bacteria suspension with a specific turbidity (0.5-10 NTU) was prepared from growing bacteria on R2A medium and injected to reactor.FindingsAt naphthalene concentration = 0.5-20 mg/L, 33–65.5% naphthalene removal efficiencies were observed. Mean COD removal efficiency in solid retention times of 2, 4, 6, and 8 days was 82.7, 92.45, 95.97 and 96.1%, respectively. Naphthalene removal efficiency by bacterium pseudomonas at pH 8 was 96% and at pH 4, 5.5, 7 and 9.5, 68, 80, 90 and 85%, respectively. As the initial concentration of naphthalene increased from 0.5 to 20 mg/L, the remaining concentration of naphthalene decreased from 33.4% to 65.5% after 3 days.ConclusionBased on experimental results, it was determined that this process can effectively reduce naphthalene under optimal conditions and this method can be used for the removal of similar compounds.

Isolation of a naphthalene-degrading strain from activated sludge and bioaugmentation with it in a MBR treating coal gasification wastewater.

A highly effective naphthalene-degrading bacterial strain was isolated from acclimated activated sludge from a coal gasification wastewater plant, and identified as a Streptomyces sp., designated as strain QWE-35. The optimal pH and temperature for naphthalene degradation were 7.0 and 35°C. The presence of additional glucose and methanol significantly increased the degradation efficiency of naphthalene. The strain showed tolerance to the toxicity of naphthalene at a concentration as great as 200 mg/L. The Andrews mode could be fitted to the degradation kinetics data well over a wide range of initial naphthalene concentrations (10-200 mg/L), with kinetic values q max = 0.84 h(-1), K s = 40.39 mg/L, and K i = 193.76 mg/L. Metabolic intermediates were identified by gas chromatography and mass spectrometry, allowing a new degradation pathway for naphthalene to be proposed for the first time. Strain QWE-35 was added into a membrane bioreactor (MBR) to enhance the treatment of real coal gasification wastewater. The results showed that the removal of chemical oxygen demand and total nitrogen were similar between bioaugmented and non-bioaugmented MBRs, however, significant removal of naphthalene was obtained in the bioaugmented reactor. The findings suggest a potential bioremediation role of Streptomyces sp. QWE-35 in the removal of naphthalene from wastewaters.

Characterization of naphthalene degradation by Streptomyces sp. QWE-5 isolated from active sludge

A bacterial strain, QWE-5, which utilized naphthalene as its sole carbon and energy source, was isolated and identified as Streptomyces sp. It was a Gram-positive, spore-forming bacterium with a flagellum, with whole, smooth, convex and wet colonies. The optimal temperature and pH for QWE-5 were 35 °C and 7.0, respectively. The QWE-5 strain was capable of completely degrading naphthalene at a concentration as high as 100 mg/L. At initial naphthalene concentrations of 10, 20, 50, 80 and 100 mg/L, complete degradation was achieved within 32, 56, 96, 120 and 144 h, respectively. Kinetics of naphthalene degradation was described using the Andrews equation. The kinetic parameters were as follows: qmax (maximum specific degradation rate) = 1.56 h⁻¹, Ks (half-rate constant) = 60.34 mg/L, and KI (substrate-inhibition constant) = 81.76 mg/L. Metabolic intermediates were identified by gas chromatography and mass spectrometry, allowing a new degradation pathway for naphthalene to be proposed. In this pathway, monooxygenation of naphthalene yielded naphthalen-1-ol. Further degradation by Streptomyces sp. QWE-5 produced acetophenone, followed by adipic acid, which was produced as a combination of decarboxylation and hydroxylation processes.

Batch study, equilibrium and kinetics of adsorption of naphthalene using waste tyre rubber granules

The potential use of waste tyre rubber granules (WTRG) for the batch adsorption of naphthalene from aqueous solutions was investigated. The effect of various operational variables such as contact time, initial naphthalene concentration, adsorbent dose, size of adsorbent particles, and temperature of solution on the adsorption capacity of WTRG was evaluated. The adsorption of naphthalene by WTRG was a fast kinetic process with an equilibrium contact time of 60 min. A low temperature (5°C), small adsorbent particle size (0.212 mm) and higher adsorbent dosage favored the adsorption process. Results of isotherm studies revealed that adsorption of naphthalene was best described by the Langmuir isotherm equation (R<sup>2</sup>=0.997) while the kinetics of the process was best described by the Lagergren pseudofirst order kinetic equation (R<sup>2</sup>=0.998). This study has demonstrated the suitability of WTRG for the removal of naphthalene from aqueous solution.

Extraction of Naphthalene from an Organic Phase with the Mixture DMSO-methanol-phenol in Batch Mode. Application of a Composite Centered Design (CCD)

The aim of this study was to improve the extraction efficiency of naphthalene from an organic phase (fuel oil) which had given already an extraction yield of about 79% using the mixture phenol-methanol as extractant. To perform this yield several extractions of naphthalene using binary and tertiary mixtures of products were proceeded. It was found that after an optimization by a mixture design, the DMSO-methanol-phenol composition used to extract naphthalene was efficiency.To study the extraction phenomena of naphthalene with the extractant mixture, a second degree experimental design called composite centered design had been used. In this paper an extraction of naphthalene from an organic phase (fuel oil) using the mixture DMSO-methanol-phenol was carried out by varying the temperature, the ratio R (Fuel/Mixture) and the initial concentration of naphthalene. After analysis of variance ANOVA, effects of parameters were studied and a model correspondent to the extraction according parameters was then applied. The optimization of these parameters showed that the extraction yield of naphthalene was almost perfect yielding 98.88%.

Bench-scale investigation of an integrated adsorption–coagulation–dissolved air flotation process for produced water treatment

In oil and gas extraction operations, water from the hydrocarbon reservoir is brought to the surface along with the oil or gas. This “produced water” contains organics which may be free, dispersed, or dissolved in the water. While certain dissolved compounds may contribute to environmental risk from produced water, current North American discharge regulations only address the dispersed fraction of oil and grease (29mg/L in the US, 30mg/L in Canada). The purpose of this research was to investigate, at bench scale, chemical coagulation with ferric chloride (FeCl3) and adsorption with organoclay (OC) in a completely stirred tank reactor (CSTR) configuration as pre-treatment for dissolved air flotation (DAF) for the removal of dissolved and dispersed oils from produced water. The integrated process was evaluated and compared to the individual processes of coagulation-DAF, adsorption-DAF and DAF without pre-treatment for the removal of dispersed oil, naphthalene and phenol from synthetic produced water. Concentrations of dispersed oil in clarified water were reduced, from an initial concentration of 100mg/L, to concentrations as low as 10±1.6mg/L after coagulation with FeCl3 (FeCl3-DAF), 15±1.2mg/L after adsorption with OC (OC-DAF), and 7±1.4mg/L after the integrated process (OC-FeCl3-DAF). From an initial naphthalene concentration of 1mg/L, both the adsorption (OC-DAF) and integrated process (OC-FeCl3) achieved clarified naphthalene concentrations of 0.11±0.01mg/L, representing a significant improvement over the 0.53±0.03mg/L achieved by coagulation treatment (FeCl3-DAF). However, none of the processes evaluated in this study were found to be effective for phenol removal.

Batch equilibrium and kinetic studies of naphthalene and pyrene adsorption onto coconut shell as low-cost adsorbent

This study investigated the use of coconut shell as a non-conventional and low-cost adsorbent for the removal of naphthalene and pyrene from synthetic waste water. Coconut shells were used to adsorb naphthalene and pyrene at varying initial naphthalene and pyrene concentrations, adsorbent dosage, particle size and agitation time. The results of the batch equilibrium adsorption studies revealed that adsorption capacity decreased with increase in particle size and increased with increase in adsorbent dosage. The equilibrium adsorption data were analysed by two-parameter models of Langmuir and Freundlich and three-parameter models of Redlich-Peterson, Sips and Toth isotherms. The results showed that the equilibrium adsorption data for naphthalene and pyrene sorbent systems fitted well with all the tested adsorption isotherm models which can adequately describe the adsorption behaviour of naphthalene and pyrene onto coconut shell. The adsorption kinetic data obtained at 100 mg/l initial naphthalene and pyrene concentrations were analysed using Lagergren pseudo-first order, Elovich and intraparticle diffusion rate equations. The rate equations fitting showed that the adsorption kinetic data generally fit the three rate equations tested from which the rate constants and diffusion rate constants were estimated. However, the Lagergren pseudo first-order rate equation gave the best fit and, thus the process followed the first-order rate kinetics. Therefore, coconut shells being an agricultural waste product have the potential to be used as a low-cost adsorbent for the removal of organic pollutant from waste water.

Kinetic modeling and isotherm study for naphthalene adsorption on boehmite nanopowder

Boehmite was synthesized and characterized in order to study the adsorption behavior and possibility to remove naphthalene as one of the polycyclic aromatic hydrocarbons (PAHs) from industrial waste water. The removal of naphthalene was investigated in terms of various parameters namely: pH, operating time, initial concentration of naphthalene and weight of adsorbent using batch technique. The data showed that the adsorption of naphthalene onto boehmite is not affected by changes in the pH. Adsorption data of naphthalene on the boehmite nanopowder were analyzed according to Freundlich, Langmuir adsorption and Redlich–Peterson models. The data were found to be best described by the Freundlich model. The kinetics of the adsorption was found to be fitted with a pseudo second order model. The negative values for free energy indicated that the spontaneous nature of the adsorption with a high performance of naphthalene for boehmite and also negative values of the enthalpies indicated that the process is exothermic. The study presented revealed that boehmite can be a promising adsorbent for the removal of PAHs such as naphthalene.