Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 90
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Artigo em Zh | MEDLINE | ID: mdl-37248187

RESUMO

Objective: To develop asolvent extraction-direct mercury analyzer method for determination of methylmercury in urine. Methods: After the urinehydrolyzesd by hydrobromic acid, methylmercury was extracted by tolueneand reverse-extracted from L-cysteine solution, it was then detectedbydirect mercuryanalyzer. Results: The linear range was 0.2-50.0 µg/L, and the related coefficient was 0.9999. The relative standard deviations (RSD) within the group were 5.04%-6.64%, and the RSD between the group were 5.65%-8.11 %. The average recovery efficiencies were 85.4%-95.5%. The detection limitation was 0.0482 µg/L and the quantification concentrations was 0.1607 µg/L. Conclusion: The method, which has low detection limit, high sensitivity, easy to operate, is stability for the determination of methylmercury in urine.


Assuntos
Mercúrio , Compostos de Metilmercúrio
2.
Ecotoxicol Environ Saf ; 225: 112759, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34500387

RESUMO

This study aimed to investigate the transformation of copper oxide nanoparticles (CuO NPs) in aquatic environments under different ionic strength and further examine its effects on copper toxicity and bioaccumulation by monitoring the responses and uptake behaviours of zebrafish embryo. Ionic strength (IS) was simulated according to surface water (1.5 mM), groundwater (15 mM), and wastewater (54 mM), representing low-, mid-, and high-IS water, respectively. At the highest exposure of 10 mg CuO/L, zebrafish larvae mortality was increased from 21.3% to 33.3%, when IS decreased from 54 to 1.5 mM. Low-IS solution also caused the highest numbers of delayed hatching embryo (81.3%) and opaque yolk deformation (36.3%). Copper bioaccumulation markedly increased when larvae were exposed to low-IS water (35%) relative to high-IS water (15%). Exposing to low-IS particularly enhanced copper uptake (~15 ng Cu/g inside embryo), facilitating the copper accumulation in the heart of larvae, whereas aggregated CuO NPs (>500 nm) in mid- and high-IS water were blocked from the embryo and found abundantly in the body axis and tail. Results indicate that CuO NPs in low-IS solutions rapidly form the relatively small CuO NP aggregates with a high copper dissolution, which would pose great concern for aquatic organisms.


Assuntos
Nanopartículas Metálicas , Nanopartículas , Poluentes Químicos da Água , Animais , Bioacumulação , Cobre/toxicidade , Nanopartículas Metálicas/toxicidade , Concentração Osmolar , Óxidos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Peixe-Zebra
3.
Zhonghua Jie He He Hu Xi Za Zhi ; 44(9): 806-811, 2021 Sep 12.
Artigo em Zh | MEDLINE | ID: mdl-34496522

RESUMO

Objective: To analyze the clinical characteristics and the diagnosis and treatment of Chlamydia psittaci pneumonia complicated with rhabdomyolysis. Methods: We reported a case of Chlamydia psittaci pneumonia complicated with rhabdomyolysis. We did a literature review on the published reports between January 1978 and May 2020 by searching with the key words of "psittacosis" or "Chlamydia psittaci" and "rhabdomyolysis" in the PubMed database (time frame: January 1, 1967 to May 30, 2020). Results: Our patient was a 64-year-old male presenting with high-grade fever, fatigue, myalgia and dyspnea. A computed tomographic scan of the chest revealed bilateral pneumonia, which was further complicated with rhabdomyolysis during disease progression. This prompted the metagenomic next-generation sequencing, revealing the sequences of Chlamydia psittaci in both the bronchoalveolar lavage fluid and blood. Of the 11 cases in the 3 literature reports that we retrieved, 5 had concomitant rhabdomyolysis (two of which did not have complete clinical information), and the other 6 cases had myositis complicated with an elevated level of creatine phosphokinase. This yielded 3 cases with complete clinical information for our analysis. We had further incorporated their information with the single case managed within our study site. Two were males and the other 2 were females. The patients were aged 66, 46, 44 and 64 years, respectively. All cases had fever and 3 had a contact history with live poultry. Two cases had myalgia and progressed rapidly into having respiratory failure, and the other 2 cases did not develop myalgia and improved significantly after a timely treatment. All 4 cases were cured and discharged after treatment with appropriate antibiotics. No adverse outcomes were observed. Conclusions: The prognosis of Chlamydia psittaci pneumonia complicated with rhabdomyolysis was poor in case of a delayed treatment. Early diagnosis would help reduce the mortality.


Assuntos
Chlamydophila psittaci , Pneumonia , Psitacose , Rabdomiólise , Líquido da Lavagem Broncoalveolar , Chlamydophila psittaci/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psitacose/complicações , Rabdomiólise/complicações
4.
Artigo em Zh | MEDLINE | ID: mdl-32629570

RESUMO

Objective: To investigate the detection of suspected occupational diseases in the occupational health examination population in Hangzhou, and to establish a two-level logistic model of influencing factors. Methods: In October 2018, the information of physical examinees was collected through the 2015-2017 occupational health examination and reexamination database of Hangzhou Hospital for the Prevention and Treatment of Occupational Disease. MlwiN 2.02 software was used to establish a 2-level logistic model of suspected occupational diseases, with the occupational hazard factors as the level 2 unit and the employees as the level 1 unit. χ(2) test was used to compare the detection rates of suspected occupational diseases with different characteristics. The trend of detection rates of suspected occupational diseases with age and working age were tested by Cochran-Armitage trend test. Results: The morbidity rate of suspected occupational diseases in 2965 workers was 59.6% (1767/2965) , and the rates caused by different occupational hazardous factors were significantly difference (χ(2)=1615.27, P<0.01) , that caused by noises was the highest (98.0%, 1206/1231) , and the next was the dust (87.5%, 70/80) . The rate in male was 61.5% (1532/2492) , and that in female was 49.7% (235/473) , they were significantly difference (χ(2)=22.96, P<0.01) . The rates of suspected occupational diseases increased with the ages (Z=8.77, P<0.01) and working years (Z=3.62, P<0.01) . The multivariate analysis by 2-level logistic model indicated that gender, age and working year were all no significant, instead the level 2 unit random effect was significant (χ(2)=4.77, P<0.05) . Conclusion: Suspected occupational diseases will occur in clusters in occupational hazardous factors. The influence of occupational hazardous factors on suspected occupational diseases was more than that of personal characteristics.


Assuntos
Doenças Profissionais/epidemiologia , Poeira , Feminino , Hospitais , Humanos , Recém-Nascido , Modelos Logísticos , Masculino , Doenças Profissionais/diagnóstico
5.
Neoplasma ; 65(6): 872-880, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-30334449

RESUMO

Long non-coding RNAs (lncRNAs) are attracting more and more attention from researchers because they are relatively new factors in regulating biological processes in human cancers. The Colorectal Neoplasia Differentially Expressed (CRNDE) lncRNA is transcribed from chromosome 16 on the opposite strand to the neighboring IRX5 gene. It was originally discovered abnormally expressed in colorectal cancer (CRC) and was certified a critical biomarker in many cancers. However, its biological function and mechanism underlying the tumorigenesis of cervical cancer still require exploration. This study confirmed that CRNDE is markedly up-regulated in clinical tissues and cell lines of cervical cancer. The high expression of CRNDE positively correlates with advanced FIGO stage and lymph node metastasis. Furthermore, the overall survival rate in the group with highly expressed CRNDE was worse, and the high level of CRNDE may be regarded a prognostic factor because of its results from proportional hazard analysis. Loss-of-function assays revealed that CRNDE influences proliferation and apoptosis in cervical cancer cells, and Western blot assays revealed that the PI3K/AKT pathway was inactivated in response to CRNDE knockdown. Therefore, we conclude that CRNDE exerts oncogenic function in cervical cancer and should be further explored as a novel prognostic predictor.


Assuntos
Apoptose , RNA Longo não Codificante/genética , Transdução de Sinais , Neoplasias do Colo do Útero/diagnóstico , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Técnicas de Silenciamento de Genes , Humanos , Fosfatidilinositol 3-Quinases , Prognóstico , Proteínas Proto-Oncogênicas c-akt , Neoplasias do Colo do Útero/genética
6.
Int Endod J ; 51 Suppl 2: e125-e145, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28439929

RESUMO

AIM: To determine the expressions of hypoxia-related [hypoxia-inducible transcription factors (HIF)-1α, BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) and phospho-adenosine monophosphate activated protein kinase (pAMPK)] and autophagy-related [microtubule-associated protein 1 light chain 3 (LC3), beclin-1 (BECN-1), autophagy-related gene (Atg)5-12, and p62] proteins in human inflammatory periapical lesions. METHODOLOGY: Fifteen samples of radicular cysts (RCs) and 21 periapical granulomas (PGs), combined with 17 healthy dental pulp tissues, were examined. Enzyme-linked immunosorbent assay (ELISA) was used to detect interleukin (IL)-1ß cytokine; immunohistochemical (IHC) and Western blot (WB) analyses were employed to examine autophagy-related and hypoxia-related proteins. Transmission electron microscopy (TEM) was used to explore the ultrastructural morphology of autophagy in periapical lesions. Nonparametric Kruskal-Wallis tests and Mann-Whitney U-tests were used for statistical analyses. RESULTS: ELISA revealed a significantly higher (P < 0.001) IL-1ß expression in periapical lesions than in normal pulp tissue. Immunoscores of IHC expressions of pAMPK, HIF-1α, BNIP3, BECN-1 and Atg5-12 proteins in periapical lesions were significantly higher (P < 0.001) (except BECN-1) than those in normal pulp tissue. The results of IHC studies were largely compatible with those of WB analyses, where significantly higher (P < 0.05) expressions of hypoxia-related and autophagy-related proteins (except BECN-1, p62 and LC3II in WB analyses) in periapical lesions were noted as compared to normal pulp tissue. Upon TEM, ultrastructural double-membrane autophagosomes and autolysosomes were observed in PGs and RCs. CONCLUSIONS: Autophagy associated with hypoxia may play a potential causative role in the development and maintenance of inflamed periapical lesions.


Assuntos
Autofagia/fisiologia , Doenças Periapicais/fisiopatologia , Adulto , Idoso , Western Blotting , Polpa Dentária/metabolismo , Polpa Dentária/fisiologia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Hipóxia/fisiopatologia , Inflamação/fisiopatologia , Interleucina-1beta/metabolismo , Masculino , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Doenças Periapicais/metabolismo , Granuloma Periapical/metabolismo , Granuloma Periapical/fisiopatologia , Cisto Radicular/metabolismo , Cisto Radicular/fisiopatologia , Adulto Jovem
7.
Water Environ Res ; 90(10): 1679-1719, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30126499

RESUMO

A review of the literature published in 2017 on topics relating to hazardous waste management in water, soils and air. This review covers hazardous waste treatment theologies and applying physical, chemical, and biological principles.


Assuntos
Resíduos Perigosos , Gerenciamento de Resíduos/métodos
8.
Zhonghua Yu Fang Yi Xue Za Zhi ; 52(6): 647-652, 2018 Jun 06.
Artigo em Zh | MEDLINE | ID: mdl-29886688

RESUMO

Objective: To analyze genomic features of pathogens based on next generation sequencing technique in a food-borne disease event. Methods: A total of 11 blood samples, stomach contents before gastric lavage from the death and patients' foods were collected. S. aureus, B. cereus and toxic substances were detected. B. cereus detected in foods were counted. The conserved region of 16 S rDNA gene and ces gene(cereulide) of B. cereus isolates were detected by real-time PCR. Next Generation Sequencing (NGS) technology was applied to acquire genome sequences of isolates. Different plasmids distribution and comparative genomics analysis with reference sequences in public databases were analyzed. Results: Only B. cereus tested positive in all samples. The counts of B. cereus in Egg fried rice, one food samples, were 1.9×10(7) CFU/g, and the counts of B. cereus in dried and fried fish and brine pork head meat samples were 3.0×10(3) CFU/g both. Ten isolates were carrying hlyⅢ, nheA, nheB, inlA and inhA genes, and nine isolates carried the plcR gene and nine isolates carried the nheC gene. The PCR result of 16 S rDNA gene and ces gene of all isolates were positive. All carried the complete ces genes cluster sequence which were identical to the sequence of plasmid pCER270 (NC_01 0924.1) from strain AH187 in United Kingdom and pNCcld (NC_016792.1) from NC7401 in Japan. The alignment of plasmids turned out the sequence of the isolate differed from the pXO1 and pXO2 plasmids of B. anthracis, but carried the pNCcld plasmid containing the ces genes cluster. The phylogenetic tree based on genomic sequences of ten isolates showed high similarity (distances in phylogenetic tree from 2.0×10(-6)-9.0×10(-6)) to each other and to the B. cereus strains AH187 and NC7401 (MLST ST26 type, distances in phylogenetic tree from 3.8×10(-5)-4.5×10(-5)). Conclusion: The foodborne disease event was caused by vomiting type Bacillus cereus without plasmid pXO1 and pXO2 contaminated egg fried rice. The vomiting-type food poisoning caused by B. Cereus globally is probably associated with ST26, ST164 and other strains harboring ces gene.


Assuntos
Bacillus cereus/genética , Doenças Transmitidas por Alimentos/microbiologia , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Tipagem de Sequências Multilocus , Filogenia , Plasmídeos
9.
Water Environ Res ; 89(10): 1461-1486, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28954671

RESUMO

This article reviews the scientific literature published in 2016 on physical, chemical, and biological treatment of hazardous contaminants and environmental bioremediation.


Assuntos
Resíduos Perigosos , Gerenciamento de Resíduos/métodos , Biodegradação Ambiental
10.
Phys Chem Chem Phys ; 18(42): 29300-29307, 2016 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-27731868

RESUMO

Passivation of surface states is known to reduce the onset photocurrent potential by removing the Fermi level pinning effect at the Helmholtz layer and enhance the photocurrent plateau by suppressing recombination loss in the space charge region. We report for the first time that metal ions can effectively passivate surface states in situ that improves the photoelectrochemical (PEC) performance of hematite electrodes. Among metal ions studied, Cr(iii), Mn(ii), Fe(ii), Co(ii), Cu(ii) and Zn(ii) were found to enhance the photocurrent by 30-300%; whereas photocurrent density significantly dropped by 90% in Ni(ii) solution after 90 min of illumination. We further hypothesized that the surface states might be the high affinity adsorption sites on hematite surfaces. Once the surface states are occupied by metal ions, along with the Schottky barrier effect at the hematite/electrolyte interface formed by adsorbed metal ions, the PEC performance is enhanced. Our results also enable the design of a potential PEC based water treatment method to extract additional energy, for example, in the brines (containing concentrated metal ions and electrolyte) of membrane processed wastewater.

11.
Water Environ Res ; 88(10): 1467-86, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27620099

RESUMO

The article reviews the scientific literature published in 2015 on physical, chemical, and biological treatment of hazardous contamination and environmental remediation.


Assuntos
Recuperação e Remediação Ambiental/métodos , Resíduos Perigosos
13.
Water Environ Res ; 87(10): 1445-70, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26420095

RESUMO

The article reviews the scientific literature published in 2014 on physical, chemical, and biological treatment of hazardous contaminants and environmental bioremediation.

14.
Chemosphere ; 304: 135276, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35690170

RESUMO

The adsorption of Pb ions, on high-density polyethylene (PE) microplastics (MPs) with the diameter of 48-500 µm, was examined in this study. According to the Langmuir isotherm, MP of the smallest size, 48 µm, had the greatest adsorption capacity of 0.38 µmol g-1. The mechanism of Pb ions adsorption onto PE MPs was chemical adsorption, in particular, hydrogen bonding and surface complexation. Pb adsorption onto PE particles was proceeded at a rapid rate, as predicted by the pseudo-second-order rate model (R2 > 0.99). The PE 48 µm had the maximum adsorption capacity of 0.44 µmol g-1 (or 0.2 mol m-2) at pH 5. While humic acid can operate as a bridging agent, boosting heavy metal adsorption on the surface of PE MPs, fulvic acid has the reverse effect. The findings indicated that PE particles may serve as a carrier of heavy metals in the aquatic environment, posing perceived risks to the environment and public health.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Adsorção , Íons , Chumbo , Microplásticos , Tamanho da Partícula , Plásticos , Polietileno , Poluentes Químicos da Água/análise
15.
Br J Cancer ; 105(12): 1830-8, 2011 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-22033270

RESUMO

BACKGROUND: Dulanermin (rhApo2L/TRAIL) induces apoptosis by binding to death receptors DR4 and DR5, leading to caspase activation and subsequent cell death. A Phase1a trial evaluated the safety and tolerability of dulanermin in patients with advanced tumours. One aim was to develop and validate pharmacodynamic biomarkers to monitor dulanermin activity in patient serum. METHODS: We optimised assays to measure the cell-death markers caspase 3/7, cytokeratin 18 and genomic DNA in serum. Mice bearing Colo205 xenografts were treated with dulanermin and sera were collected and assayed for apoptotic markers. Upon validating these assays, we monitored apoptotic markers in patients who received dulanermin. RESULTS: We detected transient increases in apoptotic markers in mouse sera 8-24 h after dulanermin treatment. This increase was dose-dependent and correlated with active caspase 3 detected by IHC in Colo205 tumours. A statistically significant increase in serum caspase 3/7 was detected in cohorts of colorectal and sarcoma patients 24 h after receiving dulanermin dosed above 4 mg kg(-1). CONCLUSION: Owing to limited responses in the Phase 1a study, the changes in circulating cell-death markers were not evaluable. Future studies with dulanermin are needed to determine the utility of these assays with respect to providing evidence of activity or predicting overall response.


Assuntos
Biomarcadores Tumorais/sangue , Neoplasias/tratamento farmacológico , Ligante Indutor de Apoptose Relacionado a TNF/uso terapêutico , Animais , Apoptose , Sequência de Bases , Primers do DNA , Humanos , Imuno-Histoquímica , Camundongos , Neoplasias/metabolismo , Neoplasias/patologia , Proteínas Recombinantes/uso terapêutico , Ensaios Antitumorais Modelo de Xenoenxerto
16.
J Hazard Mater ; 401: 123326, 2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-32653785

RESUMO

A facile impregnation method was used to fabricate a hybrid CoO-3D ordered mesoporous carbon nitride (CoO@mpgCN) catalyst that effectively activated peroxymonosulfate (PMS) for the degradation of pharmaceutical chemical, exemplified by antibiotic sulfamethoxazole (SMX) in aqueous solutions. The CoO@mpgCN/PMS system exhibited high catalytic reactivity and SMX removal efficiency over a wide pH range with an observed rate constant (kobs) of 0.314 min-1. Furthermore, CoO@mpgCN was stable with consistently high degree of SMX degradation without having cobalt dissolution and loss of catalytic activity for at least five consecutive cycles. The significant catalysis performance of CoO@mpgCN was due to its uniformly distributed mesopores, large specific surface area, and high electron transfer ability at the active CoO sites. Both quenching experiments and electron paramagnetic resonance (EPR) analysis verified the yield, in abundance, of highly active species, specifically SO4- and OH from the CoO@mpgCN activation of PMS, primarily. Hence, SMX degradation followed a radical chain reaction mechanism. The result of this study revealed a novel prospective of CoO@mpgCN composite as PMS activator for the remediation of recalcitrant pollutants in water.

17.
J Exp Med ; 186(7): 1165-70, 1997 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-9314565

RESUMO

TRAIL-R3, a new member of the TRAIL receptor family, has been cloned and characterized. TRAIL-R3 encodes a 299 amino acid protein with 58 and 54% overall identity to TRAIL-R1 and -R2, respectively. Transient expression and quantitative binding studies show TRAIL-R3 to be a plasma membrane-bound protein capable of high affinity interaction with the TRAIL ligand. The TRAIL-R3 gene maps to human chromosome 8p22-21, clustered with the genes encoding two other TRAIL receptors. In contrast to TRAIL-R1 and -R2, this receptor shows restricted expression, with transcripts detectable only in peripheral blood lymphocytes and spleen. The structure of TRAIL-R3 is unique when compared to the other TRAIL receptors in that it lacks a cytoplasmic domain and appears to be glycosyl-phosphatidylinositol-linked. Moreover, unlike TRAIL-R1 and -R2, in a transient overexpression system TRAIL-R3 does not induce apoptosis.


Assuntos
Glicoproteínas de Membrana/metabolismo , Receptores de Superfície Celular/química , Receptores de Superfície Celular/metabolismo , Receptores do Fator de Necrose Tumoral , Fator de Necrose Tumoral alfa/metabolismo , Sequência de Aminoácidos , Apoptose/fisiologia , Proteínas Reguladoras de Apoptose , Sequência de Bases , Northern Blotting , Mapeamento Cromossômico , Cromossomos Humanos Par 8/genética , Clonagem Molecular , Proteínas Ligadas por GPI , Regulação da Expressão Gênica , Glicosilfosfatidilinositóis , Humanos , Fragmentos Fc das Imunoglobulinas/genética , Células Jurkat , Linfócitos/química , Linfócitos/metabolismo , Glicoproteínas de Membrana/farmacologia , Dados de Sequência Molecular , Ligação Proteica , Receptores de Superfície Celular/genética , Membro 10c de Receptores do Fator de Necrose Tumoral , Proteínas Recombinantes de Fusão/farmacologia , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Ligante Indutor de Apoptose Relacionado a TNF , Receptores Chamariz do Fator de Necrose Tumoral , Fator de Necrose Tumoral alfa/farmacologia
18.
Chemosphere ; 242: 125259, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896176

RESUMO

Activated carbon (AC), prepared from dried loofah sponge, was supported on nickel foam to fabricate AC/Ni electrodes. The characteristics of ammonium electrosorption on AC/Ni electrodes was studied. Results showed that AC prepared in one-step activation (without pre-pyrolysis), i.e., OAC, had relatively low crystallinity, high mesoporosity, and high specific capacitance compared to those made in two-step carbonation followed by activation. Adsorption and desorption density of NH4+ were measured at constant potential of -1.0 V (vs. Hg/HgO) and +0.1 V (vs. Hg/HgO), respectively. Non-faradaic charging contributed to the electrochemical storage and adsorption of ammonium ions on the AC surface with a maximal charge efficiency of 80%, at an applied potential of -1.0 V (vs. Hg/HgO). Multiple-layer adsorption isotherm better described the electrosorption of ammonium ion on OAC/Ni electrodes yielding a maximum adsorption capacity of 6 mg-N g-1, which was comparable with other similar systems. Overall, results clearly demonstrated the effect of synthesis strategy on the capacitive charging behaviors of AC/Ni electrodes and its relationship to NH4+ electrosorption.


Assuntos
Compostos de Amônio/análise , Carvão Vegetal/química , Luffa/química , Níquel/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Capacitância Elétrica , Eletrodos , Íons , Modelos Teóricos , Propriedades de Superfície
19.
J Colloid Interface Sci ; 561: 275-286, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31757449

RESUMO

Activated alumina (AA) has been extensively applied in the defluorination of industrial wastewaters and groundwater. Although the dissolution of AA due to formation of fluoroaluminate complexes (AlFx3-x), especially in acidic condition, has been observed, its role on fluoride uptake by alumina has not been discussed in any previous literature, most of which consider F- as the sole adsorbed species. The present study described the effect of fluoroaluminate complexes on fluoride adsorption onto alumina. Results indicated that fluoroaluminate complexes, major fluoride species at pH < 6, were responsible for total fluoride adsorbed. Free fluoride ions were adsorbed mainly in the alkaline pH region, e.g., pH > 6. The dissolution of AA during defluorination was measured and analyzed by the thermodynamic solubility model. The surface concentration of F- and AlFx3-x were calculated considering electrostatic interactions. Characterization of fluoride-laden AA by XPS revealed that the fraction of surface Al-F species decreased with pH, which suggested the transition of the surface fluorinated species to that of free fluoride ions. The stability constants of four surface complexes, namely, AlOH-FAl2+, AlOH-F2Al+, AlOH2+-F- and AlOH-F-, were 106.88, 105.36, 102.72 and 102.36, respectively. Obviously fluoroaluminate complexes exhibited stronger chemical bonds with the surface hydroxy species than free fluoride.

20.
Chemosphere ; 254: 126916, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957301

RESUMO

4-Nonylphenol (4-NP), a phenolic endocrine disruptor chemical (EDC), is known to have high toxicity to aquatic organisms and humans. The remediation of 4-NP-contaminated marine sediments was studied using red algae-based biochar (RAB) thermochemically synthesized from Agardhiella subulata with simple pyrolysis process under different temperatures of 300-900 °C in CO2 atmosphere. The RAB was characterized by XRD, Raman, FTIR spectroscopy, and zeta potential measurements. The calcium in RAB efficiently activated sodium percarbonate (SPC) to generate reactive radicals for the catalytic degradation of 4-NP at pH 9.0. The oxygen-containing functional groups reacted with H2O2, which increased the generation of reactive radicals under alkaline pH condition. Ca2+ ion was the active species responsible for 4-NP degradation. CaO/CaCO3 on RAB surface enhanced direct electron transfer, increased HO production, and 4-NP degradation in marine sediments. Langmuir‒Hinshelwood type kinetics well described the 4-NP degradation process. Remediation of contaminated sediments using RAB could be a sustainable approach toward closed-loop biomass cycling in the degradation of 4-NP contaminants.


Assuntos
Carvão Vegetal/química , Disruptores Endócrinos/análise , Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos/química , Fenóis/análise , Rodófitas/química , Poluentes Químicos da Água/análise , Biomassa , Carbonatos/química , Catálise , Humanos , Peróxido de Hidrogênio/química , Cinética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA