Sorption Isotherms Of Phenanthrene Research Articles

Glomalin-related soil protein reduces the sorption of polycyclic aromatic hydrocarbons by soils

Large amounts of glomalin-related soil protein (GRSP) are present in the soil; however, the impacts of GRSP on the chemical process of soil polycyclic aromatic hydrocarbons (PAHs) are far under investigation. This research sought to elucidate the sorption of phenanthrene as a representative PAH by soils, including Kandiudult, TypicPaleudalf, and Mollisols with co-existing GRSP (0–50 mg/L). The results indicated that soil sorption capacities for phenanthrene reduced significantly. Notably, GRSP changed the sorption process of phenanthrene by Kandiudult, well described as the Freundlich model. In contrast, the phenanthrene sorption isotherms were well described with the Linear model for TypicPaleudalf and Mollisols. The reduced percentage of phenanthrene sorption due to GRSP addition was 7.01%–49.21%, 23.92%–68.71%, and17.26%–66.80% for Kandiudult, TypicPaleudalf and Mollisols, respectively. It was noted that GRSP has a strong capacity for phenanthrene sorption in aqueous solutions and elevates the availability of phenanthrene for microorganisms or plants. During the sorption process, the introduction of GRSP resulted in the reduction of organic matter in soils and elevated the concentrations of dissolved organic matter in solutions, which was the primary mechanism of GRSP-reduced phenanthrene sorption by soils. The findings revealed that GRSP enrichment can increase the mobility of PAHs in contaminated soils.

Importance of the structure and micropores of sedimentary organic matter in the sorption of phenanthrene and nonylphenol

The demineralized fraction (DM), lipid-free fraction (LF), nonhydrolyzable organic carbon fraction (NHC), and black carbon (BC) were isolated from five marine surface sediments, and they were characterized by elemental analysis as well as CO2 and N2 adsorption techniques, respectively. The NHC fractions were characterized using advanced solid-state 13C nuclear magnetic resonance (NMR) and x-ray photoelectron spectroscopy (XPS). Then, the sorption isotherms of phenanthrene (Phen) and nonylphenol (NP) on all of the samples were investigated by a batch technique. The CO2 micropore volumes were corrected for the outer specific surface areas (SSAs) by using the N2-SSA. Significant correlations between the micropore-filling volumes of Phen and NP and the micropore volumes suggested that the micropore-filling mechanism dominated the Phen and NP sorption. Meanwhile, the (O + N)/C atomic ratios were negatively and significantly correlated with the sorption capacities of Phen and NP, indicating that the sedimentary organic matter (SOM) polarity also played a significant role in the sorption process. In addition, a strong linear correlation was demonstrated between the aromatic C and the sorption capacity of Phen for the NHC fractions. This study demonstrates the importance of the micropores, polarity, and aromaticity on the sorption processes of Phen and NP in the sediments.

Importance of Sporopollenin Structure and Accessibility in the Sorption of Phenanthrene by Biota Spores and Pollens.

Although spores/pollens are so abundant and ubiquitous in the environment, the role of these natural organic matter concerning fate and transport of organic pollutants in the environment is neglected. Lipid-free fractions and sporopollenins were isolated from seven spores/pollens collected from lower and higher biota species and were characterized by elemental analysis, CO2 adsorption techniques, and advanced solid-state 13C nuclear magnetic resonance spectroscopy. Then, the sorption isotherms of phenanthrene (Phen) on all the samples were investigated by a batch technique. The sporopollenins were a highly cross-linked polymer including alkyl carbon, poly(methylene) carbon, and aromatic carbon as well as oxygen functionalities; additionally, their sorption capacities (Koc) for Phen reached up to 1 170 000 mL/g, suggesting that some of the sporopollenins were good biopolymeric sorbents for the removal of hydrophobic organic contaminants in aquatic media. A highly significant and positive correlation between the sorption capacity of Phen and the aliphaticity of the sporopollenins suggested that their structure was critical to Phen sorption. Meanwhile, the (O + N)/C atomic ratios and polar groups were significantly and negatively correlated with the sorption capacity of Phen, indicating that accessibility also played a significant role in the sorption process. Moreover, variable correlations between the sorption capacities (Koc) and the micropore volumes of the spore/pollen fractions were observed. This study sheds light on the importance of the polarity, microporosity, and structure of sporopollenins in the sorption process of Phen.

Glomalin-related soil protein enhances the sorption of polycyclic aromatic hydrocarbons on cation-modified montmorillonite

This study investigated the sorption of phenanthrene (as a representative PAH) by cation-modified montmorillonites (Ca-MMT and Fe-MMT) under the influence of Glomalin-related soil protein (GRSP) fractions (EE-GRSP and T-GRSP). Batch sorption studies were carried out as a function of GRSP concentrations (0–500 mg/L), results suggested that the sorption capacities of Ca-MMT and Fe-MMT for phenanthrene were greatly enhanced. The phenanthrene sorption isotherms were in good agreement with the Linear and Freundlich models (R2 = 0.886–0.999). The Kd values increased from 4.14 to 60.76 L/kg for Ca-MMT and from 15.57 to 153.80 L/kg for Fe-MMT with the GRSP concentrations adding from 0 to 500 mg/L, respectively. Furthermore, the sorption of phenanthrene was higher on Fe-MMT than that on Ca-MMT. It is believed that GRSP developed a higher sorption level on Fe-MMT, resulting in higher phenanthrene sorption. Microscopic and Spectroscopic analyses confirmed that the effects of GRSP on phenanthrene sorption were attributed to the changes in the surface structure and the hydrophobic property of montmorillonites. In the sorption process, GRSP may sorb onto montmorillonites through cation-π interaction when a bridge linkage was formed, and phenanthrene bound with GRSP mainly via π-π electron donor-accepter interaction. The findings could provide an in-depth understanding of the ecological functions of GRSP and provide new insights into the pathways of PAH transport and fate in the contaminated fields.

Size effect of polystyrene microplastics on sorption of phenanthrene and nitrobenzene

Microplastics can have strong sorption capacity for many contaminants, thus greatly influencing the fate, transport and bioavailability of those contaminants in the environment. However, the effect of particle size on contaminant sorption by microplastics is still poorly understood. This study investigated the sorption of phenanthrene and nitrobenzene to micron-, submicron- and nano- sized polystyrene microplastics of 170 µm, 102 µm, 50 µm, 30 µm, 800 nm, 235 nm or 50 nm. All phenanthrene sorption isotherms and most nitrobenzene sorption isotherms were linear because of the strong sorption capacity of microplastics and the hydrophobic partitioning. The log Kd values ranged between 3.07–4.20 and 1.58–3.14 log (L/kg) for phenanthrene and nitrobenzene, respectively. The log Kd values of phenanthrene and nitrobenzene both increased with decreasing particle size for micron-sized polystyrenes (micro-polystyrene) and submicron-sized polystyrenes (submicro-polystyrene). However, in comparison with 235 nm submicro-polystyrene, the log Kd values of 50 nm nano-polystyrene were significantly lower for phenanthrene and comparable for nitrobenzene because its aggregation greatly reduced the effective surface area accessible for sorption. The results improved our understanding of the fate and risks of microplastics associated with the two typical organic contaminants in the micrometer to nanometer scale.

Sorption of Phenanthrene onto Diatomite under the Influences of Solution Chemistry: A Study of Linear Sorption based on Maximal Information Coefficient

The effectiveness of diatomite as the low-cost sorbent in the removal of polycyclic aromatic hydrocarbons (PAHs) from water was investigated. The effects of ionic strength, pH, dissolved organic matter, and temperature on sorption of phenanthrene (PHE) to two types of diatomite clay (DM 545 and DM 577) were systematically studied. The maximal information coefficient (MIC) was calculated to reveal the linearity/nonlinearity in the sorption process under the influences of aqueous chemistry parameters. Results indicated that the solution parameters played an essential role in the PHE sorption behavior at the aqueous/diatomite interface. The sorption isotherms of PHE on diatomite at different temperatures could well fit the Freundlich equation. Thermodynamic studies confirmed that the sorption behavior of PHE on diatomite was spontaneous and exothermic from 283 to 303 K. The calculation of MIC revealed the linear relationship between the aqueous PAHs and sorbed PAHs at the water/diatomite interface. The results can be used to support the potential application of diatomite for the treatment of PAH-contaminated effluents.

Phenanthrene Sorption on Palygorskite Modified with Gemini Surfactants: Insights from Modeling Studies and Effects of Aqueous Solution Chemistry

The effectiveness of gemini-modified palygorskite (PGS) as the novel remediation material in polycyclic aromatic hydrocarbons (PAHs)-contaminated water remediation was revealed and examined. The sorption behavior of gemini surfactants at the PGS/aqueous interface was addressed using a developed two-step adsorption and partition model (TAPM). The characterizations of gemini-modified PGS were investigated using infrared spectroscopy, cationic exchange capacity, and surface area analysis. The effects of pH, ionic strength, humic acid, and temperature on sorption of phenanthrene (PHE) to untreated and modified PGS were systematically studied. Analysis of the equilibrium data indicated that the sorption isotherms of gemini fitted TAPM well. The modification of PGS with gemini surfactants provided a favorable partition medium for PHE and enhanced PHE retention in solid particles. The solution parameters played significant effects on PHE sorption to the modified PGS. The sorption isotherms of PHE on PGS at different temperatures well fitted the Freundlich equation. Thermodynamic calculations confirmed that the sorption process of PHE on modified PGS was spontaneous and exothermic from 293 to 303 K. It is revealed that the modification with gemini surfactants probably offered some unique surface characteristics to the clay mineral as a new type of remediation material. This can provide a reference to the potential application of PGS in PAH-contaminated water remediation process.

Preparation and characterization of a novel graphene/biochar composite for aqueous phenanthrene and mercury removal

A graphene/biochar composite (G/BC) was synthesized via slow pyrolysis of graphene (G) pretreated wheat straw, and tested for the sorption characteristics and mechanisms of representative aqueous contaminants (phenanthrene and mercury). Structure and morphology analysis showed that G was coated on the surface of biochar (BC) mainly through π–π interactions, resulting in a larger surface area, more functional groups, greater thermal stability, and higher removal efficiency of phenanthrene and mercury compared to BC. Pseudo second-order model adequately simulated sorption kinetics, and sorption isotherms of phenanthrene and mercury were simulated well by dual-mode and BET models, respectively. FTIR and SEM analysis suggested that partitioning and surface sorption were dominant mechanisms for phenanthrene sorption, and that surface complexation between mercury and C–O, CC, –OH, and OC–O functional groups was responsible for mercury removal. The results suggested that the G/BC composite is an efficient, economic, and environmentally friendly multifunctional adsorbent for environmental remediation.

Role of extractable and residual organic matter fractions on sorption of phenanthrene in sediments

Two sediments were demineralized and sequentially fractionated into extracted fractions [free lipid (FL), bound lipid (BL) and lignin (LG)] and residual fractions [free lipid free (FLF), bound lipid free (BLF) and lignin free (LGF)]. The sorption isotherms of phenanthrene (Phen) were examined to evaluate the importance of various fractions on sorption. A lignin extraction procedure was for the first time applied to separate the lignin or degraded lignin fraction from sediment organic matter (SOM). The extracted LG was similar to model lignin in terms of elemental ratios and sorption behavior. FL and LG fractions were quite important, as their contents were much higher than reported values. Phen sorption for the extracted fractions was almost linear, whereas that for the residual fractions was nonlinear, especially for LGF with n 0.56–0.63. As the different organic fractions were removed sequentially, sorption energy distribution on the residual sediment organic matter (SOM) became more heterogeneous. In addition, increasing sorption capacity for the residual fractions, except for BLF with its high polarity, suggested that more sorption sites on the SOM matrix became accessible to Phen. The sorption capacity for LGF was comparable to that of condensed SOM. The residual fraction LGF generally controlled the overall sorption at low Phen concentration, but the extractable fraction FL surpassed the former fraction at high Phen concentration, demonstrating the importance of condensed SOM in the sorption of hydrophobic organic compounds (HOCs) in sediments.

Effect of Combined Bacillus subtilis on the Sorption of Phenanthrene and 1,2,3‐Trichlorobenzene onto Mineral Surfaces

In the natural environment, minerals are often associated with coexisting microorganisms. These interactions have profound impacts on the fate of a wide variety of contaminants. However, little information is available on the sorption of hydrophobic organic compounds (HOC), such as polycyclic aromatic hydrocarbons and chlorinated benzenes, onto the composites of minerals with bacteria, and knowledge of the influence of combined bacteria on HOC sorption to minerals is limited. In our study, sorption isotherms of phenanthrene (Phen) and 1,2,3-trichlorobenzene (TCB) onto Bacillus subtilis, minerals (kaolinite, montmorillonite, and goethite), and mineral-B. subtilis composites were studied to determine the role of B. subtilis in sorption. For pure mineral systems, the order of Phen and TCB sorption affinity was montmorillonite > kaolinite > goethite. For mineral-B. subtilis composites, the trend was montmorillonite > goethite > kaolinite, consistent with that of their ability to combine with bacteria. The coating of B. subtilis with minerals enhanced the sorption due to the strong sorption of Phen and TCB onto B. subtilis cells and the increase of total organic carbon of minerals. With increasing B. subtilis concentration, sorption of Phen and TCB on pure B. subtilis cells decreased, but sorption on kaolinite surface increased. Sodium azide can greatly reduce sorption capacity but increases sorption linearity for B. subtilis and mineral-B. subtilis composites. Compared with TCB, Phen had higher sorption affinity due to its high hydrophobicity. Our results may be useful for understanding the role of bacteria in regulating the distribution and transport of HOCs in the environment.

Impact of Kerogen Heterogeneity on Sorption of Organic Pollutants. 2. Sorption Equilibria

Phenanthrene and naphthalene sorption isotherms were measured for three different series of kerogen materials using completely mixed batch reactors. Sorption isotherms were nonlinear for each sorbate-sorbent system, and the Freundlich isotherm equation fit the sorption data well. The Freundlich isotherm linearity parameter n ranged from 0.192 to 0.729 for phenanthrene and from 0.389 to 0.731 for naphthalene. The n values correlated linearly with rigidity and aromaticity of the kerogen matrix, but the single-point, organic carbon-normalized distribution coefficients varied dramatically among the tested sorbents. A dual-mode sorption equation consisting of a linear partitioning domain and a Langmuir adsorption domain adequately quantified the overall sorption equilibrium for each sorbent-sorbate system. Both models fit the data well, with r2 values of 0.965 to 0.996 for the Freundlich model and 0.963 to 0.997 for the dual-mode model for the phenanthrene sorption isotherms. The dual-mode model fitting results showed that as the rigidity and aromaticity of the kerogen matrix increased, the contribution of the linear partitioning domain to the overall sorption equilibrium decreased, whereas the contribution of the Langmuir adsorption domain increased. The present study suggested that kerogen materials found in soils and sediments should not be treated as a single, unified, carbonaceous sorbent phase.

Effects of humic acid and lipid on the sorption of phenanthrene on char

The impact of two types of natural organic matters (NOM), humic acid (HA) and lipid, on char properties and sorption affinities for phenanthrene was studied. Char was coated with HA and lipid at a concentration of 0.060, 0.250 and 0.500 g/g char. HA, lipid, char and coated char were characterized and their sorption behaviors for phenanthrene were compared. Coating with NOM increased the polarity and aliphaticity, and reduced the specific surface area (SSA) of char, depending on the coated amount and the type of NOM. At the lower HA and lipid loading there was a strong attenuation of N 2-assessible SSA. The SSA attenuation was less pronounced at larger HA and lipid loadings, which was most likely due to the preferential sorption at reactive sites and formation of clusters. The sorption isotherms of phenanthrene on char and coated char fitted Freundlich equation well, suggesting that all sorption isotherms were nonlinear, with N values in the range of 0.495–0.873. Coated char with HA and lipid decreased the organic carbon-normalized sorption coefficients K FOC and increased the N values. Lipid was more effective than HA in decreasing SSA, phenanthrene sorption capacity and sorption isotherm nonlinearity. The N values were correlated positively with the aliphaticity and negatively with pore volume of sorbents. The results of this investigation demonstrated that different NOM plays a different role in attenuating the SSA and sorption affinity of char for phenanthrene.

Sorption of phenanthrene by sewage sludge during composting in relation to potentially bioavailable contaminant content

The aim of the present study was to determine to what degree the sewage sludge sorption capacity to phenanthrene influences on bioavailability of this compound during composting. Sewage sludges were composted for 76 days. The content of the potentially bioavailable phenanthrene fraction was determined by: mild-solvent extraction with n-butanol (BTL) and non-exhaustive extraction technique with hydroxypropyl[beta] cyclodextrin (HPCD). Batch experiments were used to construct phenanthrene sorption isotherms. The contribution of the potentially bioavailable phenanthrene fraction in individual sewage sludges ranged from 32 to 48% (BTL) and from 5.1 to 80.3% (HPCD). The direction of changes in the potentially bioavailable fraction resulting from composting also depended on the sewage sludge and the extraction method applied. Isotherms demonstrated a good fit to the Freundlich isotherm model. Sorption coefficients (logK(F)) and organic carbon-normalized distribution coefficients (logK(oc)) of phenanthrene by sewage sludges ranged from 3.42 to 3.98 and from 4.14 to 4.70, respectively. Sewage sludges exhibited relatively strong affinity for sorption large amounts of phenanthrene. In the case of two sludges, a strong relationship between phenanthrene sorption capacity (logK(F) and logK(oc)) and the content of the bioavailable fraction of this compound was observed.

Sorption of Phenanthrene by Nonhydrolyzable Organic Matter from Different Size Sediments

Nonhydrolyzable organic carbon (NHC) and sorption isotherms of phenanthrene (Phen) on six size-fractionated NHC fractions in two sediments from the Pearl River and Estuary, South China, were investigated. It was found that NHC including ancient organic carbon, black carbon, resistant aquatic organic carbon, and aged soil organic carbon consists mainly of aliphatic and aromatic carbon using 13C nuclear magnetic resonance spectroscopy. The sorption isotherms of Phen by the size-fractionated NHC fractions are nonlinear and are well-fitted to the Freundlich model. For the estuary sediment, the NHC contents and the organic carbon-normalized distribution coefficients (Koc) in the size fractions increase with decreasing particle size. The clay NHC fraction contributes to 70% of the Phen sorption by the bulk NHC isolate. However, for the contaminated river sediment, the NHC contents and the Koc values exhibit no regular variations among the size fractions. The Phen sorption capacities on the size-fractionated NHC fractions of the two sediments are significantly related to their H/C ratios and aliphatic carbon, but negatively to aromatic carbon. The fine-particle NHC fractions with high aliphatic carbon and H/C ratio play a very important role in the sorption, transport, and fate of Phen by the investigated sediments.

Phenanthrene Sorption to Soil Humic Acid and Different Humin Fractions

This study was undertaken to provide an insight into the effect of heterogeneous soil organic matter (SOM) on the sorption of phenanthrene. Humic acid (HA) and humin were extracted from a peat soil. Humin was further fractionated into bound-humic acid (BHA), lipid, and insoluble residue (IR) fractions. Heterogeneous natures of these fractions were characterized by elemental analysis, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and solid-state 13C NMR. Aliphaticity of the fractions followed the order lipid >BHA > HA > IR, while the polarity order was IR > BHA> HA > lipid. Sorption of phenanthrene on these fractions fitted the Freundlich equation, suggesting that phenanthrene sorption isotherms of lipid were almost linear (N = 0.993), while those of HA, BHA, and IR were nonlinear, with N values ranging from 0.723 to 0.910. The N values followed the order lipid > HA > BHA > IR and were significantly correlated inversely with their polarities (p < 0.05). Organic carbon-normalized sorption coefficients (K(FOC)) were independent of aliphatic or aromatic contents of the SOM fractions. The results suggested that SOM, especially for the humin fractions, was highly heterogeneous in terms of elemental composition, structure, and polarity. Such heterogeneity was considered to be responsible forthe nonlinear sorption of phenanthrene.

A nonlinear parametric model for phenanthrene sorption

Two models for phenanthrene sorption prediction are discussed and checked against experimental data. The first model, based on a two-site Langmuir expression, displays too large uncertainties. The second is based on a modified Langmuir relation and provides a better description of the whole dataset. It includes an experimentally derived relation between the site maximal concentration and chemical parameters of the substrate: TOC amount and polarity index (O + N)/C. The model is tested against sorption isotherms of phenanthrene acquired with six different substrates. Calculated values display satisfying accordance with experimental data. Validity of the model is tested with an isotherm that does not belong to the set of data used for the regression, with good results. Some discrepancies may arise from analytical uncertainty and structural aspects not included within the model.

Competitive Sorption between 17α-Ethinyl Estradiol and Naphthalene/Phenanthrene by Sediments

Steroid hormones such as 17alpha-ethinyl estradiol (EE2) have been frequently detected at various levels in surface waters downstream of many municipal wastewater treatment facilities. Their fate, transport, and environmental risk are currently not well characterized. This study examined the competitive sorption between EE2 and two aromatic hydrocarbon compounds, phenanthrene and naphthalene, by three sediments. The sorption isotherms of phenanthrene and naphthalene were measured at 22 +/- 0.5 degrees C using a batch technique with initial aqueous concentrations (Co) of EE2 at 0, 100, 500, and 2000 microg/L. Competitive sorption varied between EE2 and phenanthrene or naphthalene on the sediments. The linearity of the naphthalene sorption isotherm was found to increase as a function of the cosorbate EE2 concentration from 0 to 2000 microg/L. The single-point naphthalene KD value at equilibrium aqueous-phase naphthalene concentration (Ce) of 25 microg/L was reduced by 19-26% and 27-48% at Co (EE2) = 100 and 500 microg/L, respectively. The sorption of phenanthrene at its low Ce range was similarly affected by EE2, but to a much less extent, possibly because phenanthrene is more hydrophobic than EE2. At high phenanthrene Ce, no measurable change was observed even at CO (EE2) = 2000 microg/L. While the effect of naphthalene on EE2 sorption was insignificant, the competitive effect on the sorption of EE2 by phenanthrene was very significant at low EE2 concentrations. The measured single-point EE2 KD values decreased as much as 35% as the phenanthrene Ce increases from below 10 microg/L to slightly above 100 microg/L. This study suggests that the fate and transport of emerging pollutants such as EE2 could be affected in the presence of more hydrophobic pollutants in aquatic systems.

Sorption of phenanthrene by reference smectites.

Fate and behavior of nonionic hydrophobic organic compounds (HOCs) in the environment is mainly controlled by their interactions with various components of soils and sediments. Due to their large surface area and abundance in many soils, smectites may greatly influence the fate and transport of HOCs in the environment. We used phenanthrene as a probe to explore the potential of reference smectites to sorb HOCs from aqueous solution. Batch experiments were used to construct phenanthrene sorption isotherms, and possible sorption mechanisms were inferred from the shape of the isotherms. Our results demonstrate that smectites can retain large amounts of phenanthrene from water. Phenanthrene sorption capacities of the reference smectites investigated in this study were comparable to those of soil clays containing a considerable amount of organic matter. Hectorite exhibited the highest sorption affinity and capacity followed by Panther Creek montmorillonite. The lack of correlation between Freundlich sorption constants (K'f) and indices of charge or hydrophobicity suggests that sorption of phenanthrene by smectites is primarily a physical phenomenon. Capillary condensation into a network of nanoor micropores created by quasicrystals is likely to be a dominant mechanism of phenanthrene retention by smectites.