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1.
Pediatr Infect Dis J ; 2020 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-32404786

RESUMO

BACKGROUND: To describe the characteristics of clinical manifestations of children with 2019 novel coronavirus (2019-nCoV) infection in Chongqing. METHODS: All 25 children with laboratory-confirmed 2019-nCoV infection by real-time reverse transcription-PCR (RNA-PCR) were admitted from the 4 designated treatment hospitals of 2019-nCoV in Chongqing from January 19 to March 12, 2020. Clinical data and epidemiological history of these patients were retrospectively collected and analyzed. RESULTS: The diagnosis was confirmed through RNA-PCR testing. Among the 25 cases, 14 were males and 11 were females. The median age was 11.0 (6.3-14.5) years (range 0.6-17.0 years). All children were related to a family cluster outbreak, and 7 children (28%) with a travel or residence history in Hubei Province. These patients could be categorized into different clinical types, including 8 (32%) asymptomatic, 4 (16%) very mild cases and 13 (52%) common cases. No severe or critical cases were identified. The most common symptoms were cough (13 cases, 52%) and fever (6 cases, 24%). The duration time of clinical symptoms was 13.0 (8.0-25.0) days. In the 25 cases, on admission, 21 cases (84%) had normal white blood cell counts, while only 2 cases (8%) more than 10 × 10/L and 2 cases (8%) less than 4 × 10/L, respectively; 22 cases(88%) had normal CD4+ T lymphocyte counts, while in the remaining 3 cases(8%) this increased mildly; 23 cases had normal CD8+ T lymphocyte counts, while in the remaining 2 cases (8%) CD8+ T lymphocyte counts were mildly increased as well. All Lymphocyte counts were normal. There were no statistical differences of lab results between the groups of asymptomatic cases, mild cases and common cases. There were only 13 cases with abnormal CT imaging, most of which were located in the subpleural area of the bottom of the lung. All patients were treated with interferon, 6 cases combined with Ribavirin, and 12 cases combined with lopinavir or ritonavir. The days from onset to RNA turning negative was 15.20 ± 6.54 days. There was no significant difference of RNA turning negative between the groups of interferon, interferon plus ribavirin and interferon plus lopinavir or ritonavir treatment. All the cases recovered and were discharged from hospital. CONCLUSIONS: The morbidity of 2019-nCoV infection in children is lower than in adults and the clinical manifestations and inflammatory biomarkers in children are nonspecific and milder than that in adults. RNA-PCR test is still the most reliable diagnostic method, especially for asymptomatic patients.

2.
J BUON ; 24(4): 1429-1434, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31646787

RESUMO

PURPOSE: To investigate the clinical value of spectral computed tomography (CT) imaging combined with alpha-fetoprotein (AFP) in identifying liver cancer and hepatic focal nodular hyperplasia (FNH). METHODS: A total of 132 patients with local liver space-occupying lesions, including 68 patients with liver cancer, were randomly enrolled. All the patients underwent spectral CT imaging and AFP examinations. The corresponding specificity, sensitivity, accuracy rate, positive predictive value and negative predictive value of spectral CT imaging, AFP and combined detection were recorded, respectively, with pathological findings as the gold standards. SPSS 17.0 software was used for statistical analysis. P<0.05 suggested that the difference was statistically significant. RESULTS: The diagnostic rate of spectral CT imaging was 79.5% for liver cancer and 81.3% for hepatic FNH. In arterial phase and portal venous phase, the contrast-to-noise ratio (CNR) of liver cancer was remarkably lower than that of FNH, showing a statistically significant difference, and the difference was the greatest at 70-100 keV between the two kinds of lesions. The detection rate of AFP for liver cancer was 86.8%, and the exclusive diagnostic rate of AFP for hepatic FNH was 96.9%. AFP had the highest specificity (73.2%) in identifying liver cancer and hepatic FNH. The spectral CT imaging possessed the highest sensitivity (91.7%) in identifying liver cancer and hepatic FNH. Both the sensitivity (98.1%) and accuracy (89.1%) of spectral CT imaging combined with AFP were the highest in identifying liver cancer and hepatic FNH. CONCLUSION: The spectral CT imaging combined with AFP is conducive to improving the efficiency of differential diagnosis of liver cancer and hepatic FNH.

3.
Environ Pollut ; 248: 36-47, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30771746

RESUMO

Applications of aluminium (Al) salt or lanthanum (La) modified bentonite (LMB) have become popular methodologies for immobilizing phosphorus (P) in eutrophic lakes. The presence of humic substances, has been shown to inhibit this form of treatment due to the complexation with La/Al. However, the effects of other dissolved organic matter (DOM), especially that derived from phytoplankton (the dominant source in eutrophic lakes) are unknown. In this study, the interaction with La/Al of Suwannee River Standard Humic Acid Standard II (SRHA) and algae-derived DOM (ADOM) were investigated and compared. Differed to SRHA which was dominated by polyphenol-like component (76.8%, C1-SRHA), majority in ADOM were protein-like substance, including 41.9% tryptophan-like component (C2-ADOM) and 21.0% tyrosine-like component (C3-ADOM). Two reactions of complexation and coprecipitation were observed between SRHA/ADOM and La/Al. Complexation dominated at low metal inputs less than 10 µM and coprecipitation was the main reaction at higher metal inputs. For ADOM, the tryptophan-like component (C2-ADOM) was the important component to react with metal. The reaction rate for C2-ADOM with La were about two-third of that for C1-SRHA, indicating that the influence of C2-ADOM was significant during the P immobilization by La/Al-based treatment in eutrophic lakes. The P removal data in the presence of ADOM confirmed the significant inhibition of ADOM. In addition, based on the composition of coprecipitates and relatively biodegradable character of tryptophan-like substances (C2-ADOM), the coprecipitation of ADOM was assumed to reduce the stability of precipitated P in eutrophic lakes. The release of P from the potential biodegradation of the coprecipitates and thus the possible decline of the performance of P immobilization by La/Al-based treatments is an important work in the future.


Assuntos
Alumínio/química , Bentonita/química , Eutrofização/fisiologia , Lagos/química , Lantânio/química , Fósforo/química , Rios/química , Sedimentos Geológicos/química , Substâncias Húmicas/análise , Íons , Fitoplâncton , Espectrometria de Fluorescência/métodos
5.
Transl Neurosci ; 9: 38-42, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30425851

RESUMO

Background: This study evaluated the protective effects of epifriedelinol (EFD) in a rat model of traumatic brain injury (TBI). Methodology: TBI was induced by dropping a weight from a specific height. The animals were separated into control, TBI, and EFD 100 and 200 mg/kg groups. The latter received 100 and 200 mg/kg EFD, respectively, for 2 days beginning 30 min after inducing TBI. The neurological examination score, permeability of the blood-brain barrier (BBB), water content of the brain, cytokine levels, and oxidative stress parameters were measured in the rats. The effects of EFD on glial fibrillary acidic protein (GFAP)-positive cells were evaluated using immunohistochemistry. Result: The EFD treatment significantly decreased the neurological score, permeability of the BBB, and water content of brain compared with the TBI group. The levels of interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), and oxidative stress were significantly decreased in the EFD-treated groups. The number of GFAP-positive cells was also significantly reduced in the EFD-treated groups. Conclusion: EFD attenuates the secondary injury in TBI rats by reducing the serum cytokine levels and oxidative stress.

6.
Environ Sci Technol ; 51(16): 9176-9183, 2017 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-28693315

RESUMO

Interlaced carbon nanotube electrodes (ICE) were prepared by vacuum filtering a well-dispersed carbon nanotube-Nafion solution through a laser-cut acrylic stencil onto a commercial polyvinylidene fluoride (PVDF) microfiltration (MF) membrane. Dead-end filtration was carried out using 107 and 108 CFU mL-1 Pseudomonas fluorescens to study the effects of the electrochemically active ICE on bacterial density and morphology, as well as to evaluate the bacterial fouling trend and backwash (BW) efficacy, respectively. Finally, a simplified COMSOL model of the ICE electric field was used to help elucidate the antifouling mechanism in solution. At 2 V DC and AC (total cell potential), the average bacterial log removal of the ICE-PVDF increased by ∼1 log compared to the control PVDF (3.5-4 log). Bacterial surface density was affected by the presence and polarity of DC electric potential, being 87-90% lower on the ICE cathode and 59-93% lower on the ICE anode than that on the PVDF after filtration, and BW further reduced the density on the cathode significantly. The optimal operating conditions (2 V AC) reduced the fouling rate by 75% versus the control and achieved up to 96% fouling resistance recovery (FRR) during BW at 8 V AC using 155 mM NaCl. The antifouling performance should mainly be due to electrokinetic effects, and the electric field simulation by COMSOL model suggested electrophoresis and dielectrophoresis as likely mechanisms.


Assuntos
Eletrodos , Nanotubos de Carbono , Carvão Vegetal , Filtração , Membranas Artificiais
7.
Nanoscale ; 9(20): 6854-6865, 2017 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-28497831

RESUMO

Electric-field alignment of carbon nanotubes (CNT) is widely used to produce composite materials with anisotropic mechanical, electrical, and optical properties. Nevertheless, consistent results are difficult to achieve, and even under identical electric field conditions the resulting aligned morphologies can vary over µm to cm length scales. In order to improve reproducibility, this study addresses (1) how solution processing steps (oxidation, sonication) affect CNT properties, and (2) how CNT chemistry, morphology, and dispersion influence alignment. Aligned CNT were deposited onto PVDF membranes using a combination of electric-field alignment and vacuum-filtration. At each step in solution processing, the CNT chemistry (oxygen content) and morphology (length/diameter) were characterized and compared to the final aligned morphology. Well-dispersed CNT with high oxygen content (>8.5%O) yielded uniform membrane coatings and microscopically aligned CNT, whereas CNT with low oxygen CNT (<2.2%O) produced aligned bundles visible at a macroscopic level, but microscopically the individual CNT remained disordered. Based on regression analysis, CNT with larger mean length and diameter, smaller length and diameter variation, and higher oxygen content yielded increased electrical anisotropy, and bath sonication was slightly preferable to probe sonication for initial dispersion.

8.
ChemSusChem ; 8(12): 2035-40, 2015 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-26013975

RESUMO

The traditional chamber-based microbial fuel cell (MFC) often has the disadvantages of high ohmic resistance, large volume requirements, and delayed start-up. In this study, paper-shaped MFCs utilizing a porous carbon anode, a solid Ag2 O-coated carbon cathode, and a micrometer-thin porous polyvinylidene fluoride (PVDF) separator are investigated to address the classical MFC issues. The Ag2 O-coated cathode has a low overpotential of 0.06 V at a reducing current of 1 mA compared to a Pt-air cathode. Rapid inoculation by filtration results in an instantaneous power density of 92 mW m(-2) with an internal resistance of 162 Ω. Integrated current over the first 30 min of operation has a linear relation with microbial concentration.


Assuntos
Fontes de Energia Bioelétrica , Técnicas Biossensoriais/métodos , Papel , Água/química , Técnicas Biossensoriais/instrumentação , Carbono/química , Eletrodos , Modelos Moleculares , Conformação Molecular , Óxidos/química , Polivinil/química , Porosidade , Compostos de Prata/química
9.
Appl Environ Microbiol ; 81(14): 4744-55, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25956770

RESUMO

In this study, we examine bacterial attachment and survival on a titanium (Ti) cathode coated with various carbon nanomaterials (CNM): pristine carbon nanotubes (CNT), oxidized carbon nanotubes (O-CNT), oxidized-annealed carbon nanotubes (OA-CNT), carbon black (CB), and reduced graphene oxide (rGO). The carbon nanomaterials were dispersed in an isopropyl alcohol-Nafion solution and were then used to dip-coat a Ti substrate. Pseudomonas fluorescens was selected as the representative bacterium for environmental biofouling. Experiments in the absence of an electric potential indicate that increased nanoscale surface roughness and decreased hydrophobicity of the CNM coating decreased bacterial adhesion. The loss of bacterial viability on the noncharged CNM coatings ranged from 22% for CB to 67% for OA-CNT and was dependent on the CNM dimensions and surface chemistry. For electrochemical experiments, the total density and percentage of inactivation of the adherent bacteria were analyzed semiquantitatively as functions of electrode potential, current density, and hydrogen peroxide generation. Electrode potential and hydrogen peroxide generation were the dominant factors with regard to short-term (3-h) bacterial attachment and inactivation, respectively. Extended-time electrochemical experiments (12 h) indicated that in all cases, the density of total deposited bacteria increased almost linearly with time and that the rate of bacterial adhesion was decreased 8- to 10-fold when an electric potential was applied. In summary, this study provides a fundamental rationale for the selection of CNM as cathode coatings and electric potential to reduce microbial fouling.


Assuntos
Incrustação Biológica/prevenção & controle , Técnicas Eletroquímicas/métodos , Nanotubos de Carbono/química , Pseudomonas fluorescens/fisiologia , Aderência Bacteriana , Técnicas Eletroquímicas/instrumentação , Eletrodos , Viabilidade Microbiana , Oxirredução , Pseudomonas fluorescens/crescimento & desenvolvimento , Titânio/química
10.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao ; 37(1): 118-24, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25676281

RESUMO

miRNAs are a class of noncoding RNA molecules about 18-25 nt in length. As key gene expression regulatory factors, they may inhibit or degrade mRNA by incompletely or completely complement to mRNA. Their abnormal expressions are closely related with the carcinogenesis of prostate cancer (PCa). Some miRNAs trigger cancer, while others inhibit the malignant changes. In this article we summarize the latest information on miRNAs expression prolifing and potential biomarkers,in particular the roles of miRNAs in PCa.


Assuntos
Neoplasias da Próstata , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , MicroRNAs , RNA Mensageiro
11.
Environ Sci Technol ; 49(4): 2375-83, 2015 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-25602741

RESUMO

Electro-Fenton is a promising advanced oxidation process for water treatment consisting a series redox reactions. Here, we design and examine an electrochemical filter for sequential electro-Fenton reactions to optimize the treatment process. The carbon nanotube (CNT) membrane stack (thickness ∼ 200 µm) used here consisted of 1) a CNT network cathode for O2 reduction to H2O2, 2) a CNT-COOFe(2+) cathode to chemical reduction H2O2 to (•)OH and HO(-) and to regenerate Fe(2+) in situ, 3) a porous PVDF or PTFE insulating separator, and 4) a CNT filter anode for remaining intermediate oxidation intermediates. The sequential electro-Fenton was compared to individual electrochemical and Fenton process using oxalate, a persistent organic, as a target molecule. Synergism is observed during the sequential electro-Fenton process. For example, when [DO]in = 38 ± 1 mg L(-1), J = 1.6 mL min(-1), neutral pH, and Ecell = 2.89 V, the sequential electro-Fenton oxidation rate was 206.8 ± 6.3 mgC m(-2) h(-1), which is 4-fold greater than the sum of the individual electrochemistry (16.4 ± 3.2 mgC m(-2) h(-1)) and Fenton (33.3 ± 1.3 mgC m(-2) h(-1)) reaction fluxes, and the energy consumption was 45.8 kWh kgTOC(-1). The sequential electro-Fenton was also challenged with the refractory trifluoroacetic acid (TFA) and trichloroacetic acid (TCA), and they can be transferred at a removal rate of 11.3 ± 1.2 and 21.8 ± 1.9 mmol m(-2) h(-1), respectively, with different transformation mechanisms.


Assuntos
Nanotubos de Carbono/química , Purificação da Água/métodos , Eletroquímica/instrumentação , Eletroquímica/métodos , Eletrodos , Desenho de Equipamento , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Ferro/química , Membranas Artificiais , Oxirredução , Ácido Tricloroacético/química , Ácido Trifluoracético/química , Eliminação de Resíduos Líquidos , Purificação da Água/instrumentação
12.
PLoS One ; 9(9): e105500, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25184224

RESUMO

Plant species show different responses to the elevated temperatures that are resulting from global climate change, depending on their ecological and physiological characteristics. The highly invasive shrub Lantana camara occurs between the latitudes of 35 °N and 35 °S. According to current and future climate scenarios predicted by the CLIMEX model, climatically suitable areas for L. camara are projected to contract globally, despite expansions in some areas. The objective of this study was to test those predictions, using a pot experiment in which branch cuttings were grown at three different temperatures (22 °C, 26 °C and 30 °C). We hypothesized that warming would facilitate the invasiveness of L. camara. In response to rising temperatures, the total biomass of L. camara did increase. Plants allocated more biomass to stems and enlarged their leaves more at 26 °C and 30 °C, which promoted light capture and assimilation. They did not appear to be stressed by higher temperatures, in fact photosynthesis and assimilation were enhanced. Using lettuce (Lactuca sativa) as a receptor plant in a bioassay experiment, we also tested the phytotoxicity of L. camara leachate at different temperatures. All aqueous extracts from fresh leaves significantly inhibited the germination and seedling growth of lettuce, and the allelopathic effects became stronger with increasing temperature. Our results provide key evidence that elevated temperature led to significant increases in growth along with physiological and allelopathic effects, which together indicate that global warming facilitates the invasion of L. camara.


Assuntos
Espécies Introduzidas , Lantana/crescimento & desenvolvimento , Extratos Vegetais/toxicidade , Caules de Planta/crescimento & desenvolvimento , Biomassa , Clorofila/biossíntese , Metabolismo Energético/fisiologia , Germinação/efeitos dos fármacos , Aquecimento Global , Lantana/metabolismo , Alface/efeitos dos fármacos , Alface/crescimento & desenvolvimento , Modelos Biológicos , Fotossíntese/fisiologia , Dispersão Vegetal , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Caules de Planta/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Temperatura
13.
PLoS One ; 8(11): e80623, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24265832

RESUMO

Clonal growth allows plants to spread horizontally and to experience different levels of resources. If ramets remain physiologically integrated, clonal plants can reciprocally translocate resources between ramets in heterogeneous environments. But little is known about the interaction between benefits of clonal integration and patterns of resource heterogeneity in different patches, i.e., coincident patchiness or reciprocal patchiness. We hypothesized that clonal integration will show different effects on ramets in different patches and more benefit to ramets under reciprocal patchiness than to those under coincident patchiness, as well as that the benefit from clonal integration is affected by the position of proximal and distal ramets under reciprocal or coincident patchiness. A pot experiment was conducted with clonal fragments consisting of two interconnected ramets (proximal and distal ramet) of Fragaria orientalis. In the experiment, proximal and distal ramets were grown in high or low availability of resources, i.e., light and water. Resource limitation was applied either simultaneously to both ramets of a clonal fragment (coincident resource limitation) or separately to different ramets of the same clonal fragment (reciprocal resource limitation). Half of the clonal fragments were connected while the other half were severed. From the experiment, clonal fragments growing under coincident resource limitation accumulated more biomass than those under reciprocal resource limitation. Based on a cost-benefit analysis, the support from proximal ramets to distal ramets was stronger than that from distal ramets to proximal ramets. Through division of labour, clonal fragments of F. orientalis benefited more in reciprocal patchiness than in coincident patchiness. While considering biomass accumulation and ramets production, coincident patchiness were more favourable to clonal plant F. orientalis.


Assuntos
Meio Ambiente , Fragaria/crescimento & desenvolvimento , Análise de Variância , Biomassa , Ecossistema
14.
PLoS One ; 7(9): e44221, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22957054

RESUMO

Clonal growth allows plants to spread horizontally and to establish ramets in sites of contrasting resource status. If ramets remain physiologically integrated, clones in heterogeneous environments can act as cooperative systems--effects of stress on one ramet can be ameliorated by another connected ramet inhabiting benign conditions. But little is known about the effects of patch contrast on physiological integration of clonal plants and no study has addressed its effects on physiological traits like osmolytes, reactive oxygen intermediates and antioxidant enzymes. We examined the effect of physiological integration on survival, growth and stress indicators such as osmolytes, reactive oxygen intermediates (ROIs) and antioxidant enzymes in a clonal plant, Fragaria orientalis, growing in homogenous and heterogeneous environments differing in patch contrast of water availability (1 homogeneous (no contrast) group; 2 low contrast group; 3 high contrast group). Drought stress markedly reduced the survival and growth of the severed ramets of F. orientalis, especially in high contrast treatments. Support from a ramet growing in benign patch considerably reduced drought stress and enhanced growth of ramets in dry patches. The larger the contrast between water availability, the larger the amount of support the depending ramet received from the supporting one. This support strongly affected the growth of the supporting ramet, but not to an extent to cause increase in stress indicators. We also found indication of costs related to maintenance of physiological connection between ramets. Thus, the net benefit of physiological integration depends on the environment and integration between ramets of F. orientalis could be advantageous only in heterogeneous conditions with a high contrast.


Assuntos
Secas , Fragaria/metabolismo , Antioxidantes/química , Biomassa , Meio Ambiente , Fragaria/crescimento & desenvolvimento , Peróxido de Hidrogênio/química , Luz , Fotossíntese , Folhas de Planta/metabolismo , Fenômenos Fisiológicos Vegetais , Espécies Reativas de Oxigênio , Solo , Água/química
15.
Environ Pollut ; 168: 138-44, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22610037

RESUMO

Sorption of perfluorinated compounds (PFCs) on carbon nanotubes (CNTs) is critical for understanding their subsequent transport and fate in aqueous environments, but the sorption mechanisms remain largely unknown. In this study, the sorption of six PFCs on CNTs increased with increasing C-F chain length when they had a same functional group, and the CNTs with hydroxyl and carboxyl groups had much lower adsorbed amount than the pristine CNTs, indicating that hydrophobic interaction dominated the sorption of PFCs on the CNTs. Electrostatic repulsion suppressed the sorption of PFCs on the CNTs, resulting in the lower sorption with increasing pH. Hydrogen bonding interaction was negligible. The hydrophobic C-F chains can be closely adsorbed on the CNTs surface in parallel to the axis or along the curvature, making it impossible to form micelles on the CNT surface, leading to the lower sorption than other adsorbents.


Assuntos
Fluorcarbonetos/química , Nanotubos de Carbono/química , Poluentes Químicos da Água/química , Adsorção , Recuperação e Remediação Ambiental/métodos , Interações Hidrofóbicas e Hidrofílicas , Modelos Químicos
16.
Bioresour Technol ; 102(3): 2265-71, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21044835

RESUMO

The crosslinked chitosan beads were used as an efficient biosorbent to remove perfluorooctane sulfonate (PFOS) from aqueous solution. The chitosan biosorbent had a sorption capacity up to 5.5 mmol/g for PFOS at the equilibrium concentration of 0.33 mmol/L, much higher than some conventional adsorbents. The sorption kinetics indicated that the sorption equilibrium was reached quickly at high pH and low PFOS concentrations, and the adsorbent size also affected the sorption rate to some extent. The double-exponential model described the kinetic data well, and the sorption of PFOS on the chitosan beads was a diffusion-controlled process. Based on the sorption kinetics and adsorbent characterization, the uptake mechanisms including electrostatic and hydrophobic interactions were identified to be responsible for PFOS sorption, and the hemi-micelles and micelles may form in the porous structure due to high PFOS concentrations within the adsorbent, which had the main contribution to the high sorption capacity.


Assuntos
Ácidos Alcanossulfônicos/isolamento & purificação , Quitosana/química , Fluorcarbonetos/isolamento & purificação , Modelos Químicos , Poluentes da Água/isolamento & purificação , Purificação da Água/métodos , Água/química , Absorção , Ácidos Alcanossulfônicos/química , Reagentes para Ligações Cruzadas/química , Fluorcarbonetos/química , Cinética , Microesferas , Soluções , Poluentes da Água/química
17.
Chemosphere ; 81(4): 453-8, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20797760

RESUMO

Perfluorinated compounds (PFCs) as one class of emerging pollutants have caused great attention in recent years. In this study, activated sludge was used to adsorb perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in aqueous solution in order to investigate their sorption behavior and possible uptake mechanism in wastewater treatment plants (WWTPs). Batch experiments including sorption kinetics, isotherm, and effect of solution pH and temperature were carried out. The sorption kinetics indicated that the equilibrium was reached within about 11h. The effect of pH and the zeta potential measurement implied that electrostatic repulsion prevented their sorption, but the protein composition on the heterogeneous surface of activated sludge was favorable for the sorption of PFOS and PFOA. The sorption isotherms of PFOS and PFOA as well as the comparative sorption of other PFCs with different CF chain length and different functional groups suggested that hydrophobic interaction also participated in the sorption process. Additionally, the active sorption on the living microorganism was also observed. The calculated distribution coefficient indicated that PFOS had a higher sorption tendency to activated sludge than PFOA.


Assuntos
Ácidos Alcanossulfônicos/química , Caprilatos/química , Fluorcarbonetos/química , Esgotos/química , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/química , Absorção , Adsorção , Concentração de Íons de Hidrogênio , Cinética
18.
Chemosphere ; 78(6): 688-94, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20042218

RESUMO

Perfluorinated compound as one of the emerging pollutants has caused great attention in recent years. In this study, the organo-montmorillonites (organo-Mts) with different amounts and arrangements of hexadecyltrimethylammonium bromide (HDTMAB) were prepared as effective sorbents for PFOS removal from water. Batch sorption experiments including sorption kinetics, sorption isotherm as well as effect of solution pH were studied. The Elovich and pseudo-second-order models were selected to fit the kinetic data and the latter described the sorption kinetic better. Sorption isotherms showed that the sorption amount of PFOS increased with increasing amount of HDTMAB loaded in the montmorillonites, indicating that hydrophobic interaction played an important role in the sorption process. Comparative sorption of other perfluorinated compounds (PFCs) with different length of C-F chains and different functional groups further verified that hydrophobic interaction was the main force for the sorption of PFCs on the organo-Mts. X-ray diffraction (XRD) analysis demonstrated the significant decrease of interlayer distance after PFOS sorption, suggesting that the HDTMAB molecules were rearranged in the interlayer of organo-Mts. The PFOS molecules first diffused into the organo-Mts via hydrophobic interaction, and then the rearrangement occurred through electrostatic interaction between the two surfactants, resulting in the microstructure change within the organo-Mts.


Assuntos
Ácidos Alcanossulfônicos/química , Bentonita/química , Compostos de Cetrimônio/química , Fluorcarbonetos/química , Adsorção , Cetrimônio , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica
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