kaolinite and phenanthrene

Investigate the effect of soil organic matter (SOM) and low molecular weight organic acids (LMWOAs) on minerals adsorption of PAHs. Batch adsorption experiments have been carried out to study the adsorption of PAHs (Naphthalene (NaP), Phenanthrene (Phe) and Pyrene (Pyr)) by minerals (Montmorillonite (Mnt), kaolinite (Kln) and calcite (Cal)). This research found that compared with Kln and Cal, Mnt showed the maximum adsorption capability for PAHs. And the order of PAHs adsorption by Mnt was: Pyr > Phe > Nap, which corresponds to the octanol-water partition coefficient (K

Topics: Adsorption; Bentonite; Calcium Carbonate; Kaolin; Minerals; Molecular Weight; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Soil

Natural and cost-effective materials such as minerals can serve as supportive matrices to enhance biodegradation of polycyclic aromatic hydrocarbons (PAHs). In this study we evaluated and compared the regulatory role of two common soil minerals, i.e. kaolinite and quartz in phenanthrene (a model PAH) degradation by a PAH degrader Sphingomonas sp. GY2B and investigated the underlying mechanism. Overall kaolinite was more effective than quartz in promoting phenanthrene degradation and bacterial growth. And it was revealed that a more intimate association was established between GY2B and kaolinite. Si and O atoms on mineral surface were demonstrated to be involved in GY2B-mineral interaction. There was an higher polysaccharide/lipid content in the EPS (extracellular polymeric substances) secreted by GY2B on kaolinite than on quartz. Altogether, these results showed that differential bacterial growth, enzymatic activity, EPS composition as well as the interface interaction may explain the effects minerals have on PAH biodegradation. It was implicated that different interface interaction between different minerals and bacteria can affect microbial behavior, which ultimately results in different biodegradation efficiency.

Topics: Biodegradation, Environmental; Biopolymers; Kaolin; Phenanthrenes; Quartz; Sphingomonas

Interactions between microorganisms and minerals have the potential contribution to remove polycyclic aromatic hydrocarbons (PAHs) in model systems. In this study, phenanthrene (PHE) was used as a probe molecule to explore the potential adsorption and biotransformation processes in the presence of microorganisms and various reference clays, such as montmorillonite (M), kaolinite (K), and pyrophyllite (P). Equilibrium adsorption experiments and scanning electron microscopy (SEM) technique were used to investigate the sorption of Pantoea agglomerans strains on clay minerals saturated with cations (Na

Topics: Adsorption; Aluminum Silicates; Bentonite; Biodegradation, Environmental; Cations; Clay; Ferric Compounds; Kaolin; Minerals; Pantoea; Phenanthrenes; Sodium; Soil Pollutants

Natural soil montmorillonite and kaolinite nanoparticles (NPs) were tested as efficient sorbents for organic contaminant (OC) removal through mimicking their natural environmental dispersive states. Sorption of both mineral NPs decreased with increasing pH with ionizable pentachlorophenol (PCP), but increased with pH with non-ionizable phenanthrene (PHE), within the pH range of 4-10. In contrast, sorption decreased consistently for both PCP and PHE, as a function of increasing ion concentration (0.001-0.1 mol L(-1)). Sorption differences were likely caused by the electrolytic conditions dependent upon surface chemistry of OCs and mineral NPs. The results confirmed that the highly dispersive soil mineral NPs would prevail over both engineered NPs and their regular μm-sized colloids for OC removal, due to their ecological advantages and higher sorption properties. This finding provided a realistic assessment of the environmental function of soil natural minerals in water once they are released from soil into OC polluted aqueous systems.

Topics: Adsorption; Bentonite; Environmental Monitoring; Hydrogen-Ion Concentration; Kaolin; Nanoparticles; Pentachlorophenol; Phenanthrenes; Soil; Soil Pollutants; Surface Properties; Water; Water Pollution

Sorption of phenanthrene onto the natural sediment with low organic carbon content (OC%), organic-free sediment, and kaolinite was investigated through isotherm experiments. Effects of cosolutes (pyrene, 4-n-nonyphenol (NP), and humic acid (HA)) on phenanthrene sorption were also studied by comparing apparent solid-water distribution coefficients (K d (app)) of phenanthrene. Two addition sequences, including "cosolute added prior to phenanthrene" and "cosolute and phenanthrene added simultaneously," were adopted. The Freundlich model fits phenanthrene sorption on all 3 sorbents well. The sorption coefficients on these sorbents were similar, suggesting that mineral surface plays an important role in the sorption of hydrophobic organic contaminants on low OC% sediments. Cosolutes could affect phenanthrene sorption on the sorbents, which depended on their properties, concentrations, and addition sequences. Pyrene inhibited phenanthrene sorption. Sorbed NP inhibited phenanthrene sorption at low levels and promoted sorption at high levels. Similar to NP, effect of HA on phenanthrene sorption onto the natural sediment depended on its concentrations, whereas, for the organic-free sediment and kaolinite, preloading of HA at high levels led to an enhancement in phenanthrene K d (app) while no obvious effect was observed at low HA levels; dissolved HA could inhibit phenanthrene sorption on the two sorbents.

Topics: Environmental Monitoring; Geologic Sediments; Kaolin; Minerals; Phenanthrenes; Rivers

The effect of sorbed nonylphenol (NP) at low levels on phenanthrene sorption onto the mineral surfaces (organic-removed sediment, kaolinite) and a natural sediment with low organic content was investigated in this study. NP could be sorbed on the sediment and the minerals, and part of sorbed NP interacted with the solid surface stably. At very low concentrations, sorbed NP was observed to inhibit the sorption of phenanthrene on the hydrophilic mineral surfaces (organic-removed sediment and kaolinite) based on the change of phenanthrene apparent solid-liquid distribution coefficients. When the amount of sorbed NP increased to higher levels, enhancement of phenanthrene sorption occurred. Similar result was also obtained in isotherm experiments. On the mineral sorbents contacting with 1.0 mg/L NP solution previously, the K(d) values were lower compared with those on the sorbents without sorbed NP. On the sorbents with higher levels of sorbed NP (contacting with 10 mg/L NP solution previously), the K(d) values increased, while the isotherm tended to be more nonlinear. Concentrations of sorbed NP determined its orientation on the surface, which could presumably affect the water film above the sorbents, or contribute more adsorption sites for phenanthrene.

Topics: Adsorption; Chemistry, Organic; Environmental Monitoring; Geologic Sediments; Kaolin; Kinetics; Minerals; Phenanthrenes; Phenols; Soil Pollutants; Surface Properties; Water

Polycyclic aromatic hydrocarbons (PAHs) cause a high environmental impact when released into the environment. The objective of this study was to evaluate the capacity to decontaminate polluted soils with phenanthrene as a model PAH using a combination of two technologies: electrokinetic remediation and Fenton process. Kaolinite was used as a model sample that was artificially polluted at the laboratory at an initial concentration of phenanthrene of 500 mg kg(-1) of dried kaolinite. The standard electrokinetic process resulted in negligible removal of phenanthrene from the kaolinite sample. Faster and more efficient degradation of this compound can be promoted by introduction of a strong oxidant into the soil such as hydroxyl radicals. For this reason, the Fenton reactions have been induced in several experiments in which H(2)O(2) (10%) was used as flushing solution, and kaolinite polluted with iron was used. When anode and cathode chambers were filled with H(2)O(2) (10%), the kaolinite pH is maintained at an acid value around 3.5 without pH control and an overall removal and destruction efficiency of phenanthrene of 99% was obtained in 14 days by applying a voltage gradient of 3 V cm(-1). Therefore, it is evident that a combined technology of electrokinetic remediation and Fenton reaction is capable of simultaneously removing and degrading of PAHs in polluted model samples with kaolinite.

Topics: Electrochemistry; Environmental Restoration and Remediation; Hydrogen Peroxide; Hydrogen-Ion Concentration; Kaolin; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Soil Pollutants

In this work a two-stage process combining soil electrokinetic remediation and liquid electrochemical oxidation for the remediation of polluted soil with organic compounds has been developed and evaluated using phenanthrene-spiked kaolinite. Application of an unenhanced electrokinetic process resulted in negligible removal of phenanthrene from the kaolinite sample. Addition of co-solvents and electrolyte to the processing fluid used in the electrode chambers enhanced phenanthrene desorption from the kaolinite matrix and favoured electro-osmotic flow. Near-complete removal of phenanthrene was achieved using Na2SO4 and ethanol in the processing fluid. Phenanthrene was transported towards the cathode chamber where it was collected. The cathodic solution containing the pollutant was treated by electrochemical oxidation; complete degradation of phenanthrene occurred after 9 h using Na2SO4 as electrolyte.

Topics: Electrochemistry; Environmental Restoration and Remediation; Ethanol; Kaolin; Oxidation-Reduction; Phenanthrenes; Polysorbates; Soil Pollutants; Solvents; Sulfates; Surface-Active Agents

Removal of hydrophobic organic contaminants (HOCs) using surfactant-enhanced electrokinetic (EK) method was studied in a model system. Kaolinite and phenanthrene were selected as a model clay soil and a representative HOC, respectively. Three different types of surfactants: APG (alkyl polyglucoside), Brij30 (polyoxyethylene-4-lauryl ether), and SDS (sodium dodecyl sulfate), were used to enhance the solubility of HOC. Characteristics of surfactants, such as surface tension, HOC solubility, and biodegradability were measured. In the case of Brij30 solution, phenanthrene solubility was higher than that of others. After 4 days, APG and Brij30 were degraded by 65% and 26% of the initial amount, respectively. However, degradation of SDS was hardly detected. Electroosmotic flow (EOF) of Brij30 solution was lower than others when the 0.1M NaCl was used as electrolyte. Addition of the acetate buffer solution increased the EOF of Brij30 solution and enhanced removal of phenanthrene. Among three different surfactants tested, APG showed the highest removal efficiency.

Topics: Electroosmosis; Glucans; Kaolin; Phenanthrenes; Polidocanol; Polyethylene Glycols; Sodium Dodecyl Sulfate; Soil; Solubility; Surface-Active Agents

Kaolins contaminated with heavy metals, Cu and Pb, and organic compounds, p-xylene and phenanthrene, were treated with an upward electrokinetic soil remediation (UESR) process. The effects of current density, cathode chamber flushing fluid, treatment duration, reactor size, and the type of contaminants under the vertical non-uniform electric field of UESR on the simultaneous removal of the heavy metals and organic contaminants were studied. The removal efficiencies of p-xylene and phenanthrene were higher in the experiments with cells of smaller diameter or larger height, and with distilled water flow in the cathode chamber. The removal efficiency of Cu and Pb were higher in the experiments with smaller diameter or shorter height cells and 0.01M HNO(3) solution as cathode chamber flow. In spite of different conditions for removal of heavy metals and organics, it is possible to use the upward electrokinetic soil remediation process for their simultaneous removal. Thus, in the experiments with duration of 6 days removal efficiencies of phenanthrene, p-xylene, Cu and Pb were 67%, 93%, 62% and 35%, respectively. The experiment demonstrated the feasibility of simultaneous removal of organic contaminants and heavy metals from kaolin using the upward electrokinetic soil remediation process.

Topics: Copper; Electrochemistry; Environmental Restoration and Remediation; Kaolin; Lead; Phenanthrenes; Soil Pollutants; Xylenes

The electrokinetic-Fenton (EK-Fenton) remediation of soil contaminated with phenanthrene was studied. Two different soils were chosen to investigate the effects of chemical properties, such as Fe oxide contents and acid soil buffer capacity. The H(2)O(2) concentrations in pore water, the electrical potential distributions and the electrical currents were monitored to assess the electrochemical effect in relation to the soil properties. Hadong caly had high acid buffer capacity, and thus the amount of electroosmotic flow was lager in the experiment with Hadong clay than with EPK kaolin. The major mechanism of phenanthrene removal was a degradation in the experiment with EPK Kaolin, while it was a simple transport away from the system in experiment with Hadong clay. It was mainly because of the lower acid buffering capacity and better H(2)O(2) stability in case with EPK Kaolin than with Hadong clay.

Topics: Aluminum Silicates; Buffers; Carbonates; Clay; Electrochemistry; Hydrogen Peroxide; Hydrogen-Ion Concentration; Iron; Kaolin; Phenanthrenes; Soil; Soil Pollutants; Sulfates; Waste Management

This study explored the feasibility of applying the electrokinetic-Fenton process (EK-Fenton process) for the remediation of contaminant sorbed onto soil possessing low-permeability. The relationship of H2O2 stability and phenanthrene treatment, and the variation in the monitoring values were also investigated during the EK-Fenton process when catalyzed by heterogeneous minerals. Phenanthrene was chosen to represent hydrophobic organic contaminants (HOCs), which are widespread in the environment, and kaolinite was used as the low-permeability soil. In these experiments, the H2O2 concentrations in pore water, the electrical potential distributions and the electrical currents were measured or monitored to assess the electrochemical effect in relation to injections of H2O2 from the anode. The results suggested that intermediate anions (HO2-, O2-) with Fenton-like reaction affected significantly the variations in the electrical current during the EK-Fenton process. The addition of 0.01 N H2SO4 to the anode reservoir improved the H2O2 stability and the treatment of phenanthrene in the entire soil specimen. Therefore, use of H2O2 and dilute acid, as an anode purging solution is a possible method for treating HOCs in low-permeability subsurface environments.

Topics: Catalysis; Electrochemistry; Hydrogen Peroxide; Iron; Kaolin; Kinetics; Permeability; Phenanthrenes; Soil Pollutants

The adsorption of heavy fuel oil No. 2 (F2) on a reference kaolinite (Arvor kaolin, France), and the influence of this anthropic organic matter on the phenanthrene (PHEN) retention capacity of a kaolinite were investigated in the laboratory. The heaviest and most polar compounds of F2 are adsorbed on kaolinite preferentially to the other compounds and also partly irreversibly. The precoating of kaolinite by F2 significantly increases the sorption of PHEN in the range of concentrations studied (10-500 microg l(-1)). The partition coefficients normalized to organic carbon content (Koc) of kaolin precoated with fuel oil (5.2 < log Koc < 5.5) are one order of magnitude higher than those of the original kaolin (4.2 < logKoc < 4.5), and show very good agreement with the literature for polluted industrial soils. The Koc measured on the uncoated kaolin are in close agreement with the values determined for natural soils in which humic substances represent the organic component. This demonstrates that the composition of organic matter is the primary factor in PHEN retention by the soils. Therefore, in predicting the transport of PHEN, and other Polycyclic aromatic hydrocarbons (PAHs) in general, in soils of industrial sites containing heavy hydrocarbons or tars requires that the specific nature of the organic matter contained in these soils be taken into consideration.

Topics: Adsorption; Aluminum Silicates; Antidiarrheals; Clay; Fuel Oils; Kaolin; Organic Chemicals; Phenanthrenes; Polycyclic Compounds; Soil Pollutants