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1.
Small ; : e2404417, 2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-39039986

RESUMEN

The photocatalytic U(VI) reduction is regarded as an effective strategy for recovering uranium. However, its application in seawater uranium extraction poses challenges due to limited reactivity in the presence of carbonate and under atmospheric conditions. In the present study, a photoactive hydrogel made of carboxyl-functionalized g-C3N4/CdS (CCN/CdS) is designed for extracting uranium. The carboxyl groups on g-C3N4 enhance the affinity toward uranyl ions while CdS facilitates the activation of dissolved oxygen. Under atmospheric conditions, the prepared hydrogel catalyst achieves over 80% reduction rate of 0.1 mM U(VI) within 150 min in the presence of carbonate, without the assistance of any electron donors. During the photocatalytic process, U(VI) is reduced to form UO2+x. The hydrogel catalyst exhibits a high uranium extraction capacity of >434.5 mg g⁻1 and the products can be effectively eluted using a 0.1 M NaCO3 solution. Furthermore, this hydrogel catalyst offers excellent stability, good recyclability, outstanding antifouling activity, and ease of separation, all of which are desirable for seawater uranium extraction. Finally, the test in real seawater demonstrates the successful extraction of uranium from seawater using the prepared hydrogel catalyst.

2.
New Phytol ; 238(5): 2113-2129, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-36945893

RESUMEN

Legumes establish symbioses with rhizobia by forming nitrogen-fixing nodules. Nitrate is a major environmental factor that affects symbiotic functioning. However, the molecular mechanism of nitrate-induced nodule senescence is poorly understood. Comparative transcriptomic analysis reveals an NAC-type transcription factor in Lotus japonicus, LjNAC094, that acts as a positive regulator in nitrate-induced nodule senescence. Stable overexpression and mutant lines of NAC094 were constructed and used for phenotypic characterization. DNA-affinity purification sequencing was performed to identify NAC094 targeting genes and results were confirmed by electrophoretic mobility shift and transactivation assays. Overexpression of NAC094 induces premature nodule senescence. Knocking out NAC094 partially relieves nitrate-induced degradation of leghemoglobins and abolishes nodule expression of senescence-associated genes (SAGs) that contain a conserved binding motif for NAC094. Nitrate-triggered metabolic changes in wild-type nodules are largely affected in nac094 mutant nodules. Induction of NAC094 and its targeting SAGs was almost blocked in the nitrate-insensitive nlp1, nlp4, and nlp1 nlp4 mutants. We conclude that NAC094 functions downstream of NLP1 and NLP4 by regulating nitrate-induced expression of SAGs. Our study fills in a key gap between nitrate and the execution of nodule senescence, and provides a potential strategy to improve nitrogen fixation and stress tolerance of legumes.


Asunto(s)
Lotus , Nódulos de las Raíces de las Plantas , Nódulos de las Raíces de las Plantas/metabolismo , Nitratos/farmacología , Nitratos/metabolismo , Factores de Transcripción/metabolismo , Fijación del Nitrógeno/genética , Lotus/metabolismo , Simbiosis/fisiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulación de la Expresión Génica de las Plantas
3.
Environ Res ; 236(Pt 2): 116819, 2023 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-37541418

RESUMEN

In this study, a series of biochar were prepared via pyrolyzing cellulose-rich pakchoi (PBC) and lignin-rich corncob (CBC) to explore the photoreduction process of Cr(VI). X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy confirmed higher oxygenated functional groups in PBC (48.9%-57.1%), whereas CBC exhibited more aromatization properties due to the stable aromatic network in lignin. For PBC, the valence bands decreased from 1.42 eV to 1.20 eV with the increase of pyrolysis temperature from 300 °C to 500 °C; however, an opposite trend was observed for CBC. The photoreduction of Cr(VI) clearly showed that both PBC and CBC had the best performance at the carbonization temperature of 300 °C (named PBC300 and CBC300). It is noted that PBC300 exhibited the most effective photoreduction of Cr(VI), which was about 1.3 times higher than that of CBC300. The maximum reduction capacities of Cr(VI) were 68.2 mg g-1 on PBC300 and 66.1 mg g-1 on CBC300 at pH∼2.0. Compared with the insoluble char substances, dissolved black carbons made more contributions for Cr(VI) photoreduction, ∼70% in PBC and almost 100% in CBC, which suggested that in the case of PBC, the insoluble char and the corresponding dissolved black carbons play an important role in the photoreduction of Cr(VI). However, only dissolved black carbons contributed to Cr(VI) photoreduction on CBC. As the key reaction pathway, the interfacial electron transport dominated Cr(VI) reduction on PBC and CBC. Moreover, the radical of •O2- had some contribution to the reduction of Cr(VI) only in the PBC system. Interestingly, •OH could promote the photoreduction of Cr(VI) in both PBC and CBC systems, which might be due to the fact that •OH facilitated the formation of small molecule fragments. These findings provide an essential basis for evaluating the environmental impact of photocatalytic behaviors of biochar.


Asunto(s)
Lignina , Contaminantes Químicos del Agua , Celulosa , Carbón Orgánico/química , Cromo/análisis , Adsorción , Contaminantes Químicos del Agua/análisis
4.
Environ Res ; 231(Pt 3): 116313, 2023 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-37270080

RESUMEN

A novel photo-Fenton catalyst α-Fe2O3@g-C3N4@NH2-MIL-101(Fe) (FGN) with dual Z-scheme heterojunction was successfully prepared by hydrothermal method to degrade tetracycline (TC). The preparation conditions were optimized by orthogonal test, and the successful synthesis was confirmed by characterization analyses. The prepared FGN showed better light absorption performance, higher photoelectrons-holes separation efficiency, lower photoelectrons transfer resistance, and higher specific surface area and pore capacity compared with α-Fe2O3@g-C3N4 and α-Fe2O3. The effects of experimental conditions on the catalytic degradation of TC were investigated. The degradation rate of 10 mg/L TC could reach 98.33% within 2 h when the dosage of FGN was 200 mg/L, and the degradation rate could remain 92.27% after 5 times of reuse. Furthermore, the XRD spectra and XPS spectra of FGN before and after reuse were compared to explore the structural stability and catalytic active sites of FGN, respectively. According to the identification of oxidation intermediates, three degradation pathways of TC were proposed. Through H2O2 consumption experiment, radical-scavenging experiments, EPR results, the mechanism of the dual Z-scheme heterojunction was proved. The improved performance of FGN was attributed to the dual Z-Scheme heterojunction effectively promoting the separation of photogenerated electrons from the holes and accelerating the electrons transfer, and the increase of the specific surface area.


Asunto(s)
Peróxido de Hidrógeno , Estructuras Metalorgánicas , Tetraciclina , Antibacterianos , Catálisis
5.
J Environ Manage ; 339: 117928, 2023 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-37060692

RESUMEN

Phytoremediation of total petroleum hydrocarbons (TPHs) contamination is a process that uses the synergistic action of plants and rhizosphere microorganisms to degrade, absorb and stabilize pollutants in the soil, and has received increasing attention in recent years. However, this technology still has some challenges under certain conditions (e.g., highly alkaline and saline environments). The present study was selected three native plant species (alfalfa, tall fescue, and ryegrass) to remediate petroleum pollutants in greenhouse pot experiments. The results indicate that TPH contamination not only inhibited plant growth, soil chemical properties and soil fertility (i.e. lower plant biomass, chlorophyll, pH, and electrical conductivity), but also increased the malondialdehyde, glutathione, and antioxidant enzyme activities (catalase and polyphenol oxidase). Further, correlation analysis results illustrated that TPH removal was strongly positively correlated with chlorophyll, soil fertility, and total organic carbon, but was negatively correlated with dehydrogenase, polyphenol oxidase, pH, and electrical conductivity. The highest TPHs removal rate (74.13%) was exhibited by alfalfa, followed by tall fescue (61.79%) and ryegrass (57.28%). The degradation rates of short-chain alkanes and low rings polycyclic aromatic hydrocarbons (PAHs) were substantially higher than those of long-chain alkanes and high rings PAHs. The findings of this study provide valuable insights into petroleum decontamination strategies in the highly saline - alkali environments.


Asunto(s)
Contaminantes Ambientales , Lolium , Petróleo , Contaminantes del Suelo , Álcalis , Suelo/química , Petróleo/análisis , Contaminantes del Suelo/análisis , Plantas/metabolismo , Biodegradación Ambiental , Microbiología del Suelo , Hidrocarburos/química , Alcanos , Contaminantes Ambientales/análisis
6.
Molecules ; 27(6)2022 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-35335223

RESUMEN

The environmental behaviors of uranium closely depend on its interaction with natural minerals. Ferrihydrite widely distributed in nature is considered as one main natural media that is able to change the geochemical behaviors of various elements. However, the semiconductor properties of ferrihydrite and its impacts on the environmental fate of elements are sometimes ignored. The present study systematically clarified the photocatalysis of U(VI) on ferrihydrite under anaerobic and aerobic conditions, respectively. Ferrihydrite showed excellent photoelectric response. Under anaerobic conditions, U(VI) was converted to U(IV) by light-irradiated ferrihydrite, in the form of UO2+x (x < 0.25), where •O2− was the dominant reactive reductive species. At pH 5.0, ~50% of U(VI) was removed after light irradiation for 2 h, while 100% U(VI) was eliminated at pH 6.0. The presence of methanol accelerated the reduction of U(VI). Under aerobic conditions, the light illumination on ferrihydrite also led to an obvious but slower removal of U(VI). The removal of U(VI) increased from ~25% to 70% as the pH increased from 5.0 to 6.0. The generation of H2O2 under aerobic conditions led to the formation of UO4•xH2O precipitates on ferrihydrite. Therefore, it is proved that light irradiation on ferrihydrite significantly changed the species of U(VI) and promoted the removal of uranium both under anaerobic and aerobic conditions.


Asunto(s)
Peróxido de Hidrógeno , Uranio , Medios de Cultivo , Compuestos Férricos , Iluminación
7.
Int J Mol Sci ; 22(15)2021 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-34360533

RESUMEN

Carbonic anhydrase (CA) plays a vital role in photosynthetic tissues of higher plants, whereas its non-photosynthetic role in the symbiotic root nodule was rarely characterized. In this study, 13 CA genes were identified in the model legume Lotus japonicus by comparison with Arabidopsis CA genes. Using qPCR and promoter-reporter fusion methods, three previously identified nodule-enhanced CA genes (LjαCA2, LjαCA6, and LjßCA1) have been further characterized, which exhibit different spatiotemporal expression patterns during nodule development. LjαCA2 was expressed in the central infection zone of the mature nodule, including both infected and uninfected cells. LjαCA6 was restricted to the vascular bundle of the root and nodule. As for LjßCA1, it was expressed in most cell types of nodule primordia but only in peripheral cortical cells and uninfected cells of the mature nodule. Using CRISPR/Cas9 technology, the knockout of LjßCA1 or both LjαCA2 and its homolog, LjαCA1, did not result in abnormal symbiotic phenotype compared with the wild-type plants, suggesting that LjßCA1 or LjαCA1/2 are not essential for the nitrogen fixation under normal symbiotic conditions. Nevertheless, the nodule-enhanced expression patterns and the diverse distributions in different types of cells imply their potential functions during root nodule symbiosis, such as CO2 fixation, N assimilation, and pH regulation, which await further investigations.


Asunto(s)
Anhidrasas Carbónicas/metabolismo , Regulación de la Expresión Génica de las Plantas , Lotus/enzimología , Fijación del Nitrógeno , Proteínas de Plantas/metabolismo , Nódulos de las Raíces de las Plantas/enzimología , Simbiosis , Anhidrasas Carbónicas/genética , Lotus/genética , Lotus/crecimiento & desarrollo , Fenotipo , Proteínas de Plantas/genética , Nódulos de las Raíces de las Plantas/genética , Nódulos de las Raíces de las Plantas/crecimiento & desarrollo
8.
Ecotoxicol Environ Saf ; 192: 110320, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-32061982

RESUMEN

Extensive mining and smelting activities in the Baiyin district have resulted in a serious hazardous elements (HEs) contamination in the soils and overbank sediments. In this study, the concentrations and chemical fractions of HEs were analyzed to evaluate the environmental risks of these HEs in the focus areas. In soils, Zn, Cu, Pb, and Cd exhibited an obvious decline compared to the results in 2012, which confirmed that the treatments of the contaminated soils by the government have played a very important role in the remediation of the soils. However, Zn, Cu, and Pb still exceeded the background values, and the study areas were still extremely contaminated with Cd. The spatial distribution of HEs showed that the contaminated areas were mainly focused around the mining and smelting regions and the sewage irrigation regions. Sequential extraction showed that Zn was mainly present as a residue fraction, while the percentages of unstable fractions increased in the sewage irrigation region samples. As for Cd, the bioavailable fractions were extremely high (over 90%) and the ecological risk was much higher than Zn. In the case of the sediments, the concentrations of HEs were extremely high. However, few researches have investigated HEs contamination in the sediments from the study area. With changes in climate and environmental conditions, HEs in sediments will easily release and influence the groundwater and the irrigation water. Furthermore, the available fractions of Zn and Cd were over 80%, which suggests high bioavailability and mobility in sediments. HEs pollution in sediments should receive more attention compared to that in soils.


Asunto(s)
Sedimentos Geológicos/química , Metalurgia , Metales Pesados/análisis , Minería , Contaminantes del Suelo/análisis , Monitoreo del Ambiente , Sustancias Peligrosas/análisis , Aguas del Alcantarillado/química
9.
J Environ Sci (China) ; 75: 115-123, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30473276

RESUMEN

Sorption of U(VI) onto TiO2 as functions of pH, ionic strength, contact time, soil humic acid (SHA), solid-to-liquid ratio and temperature was studied under ambient conditions using batch and spectroscopic approaches. The sorption of U(VI) on TiO2 was significantly dependent on pH and ionic strength. The presence of SHA slightly enhanced the sorption of U(VI) on TiO2 below pH4.0, while it inhibited U(VI) sorption in the higher pH range. U(VI) sorption on TiO2 was favored at high temperatures, and the sorption process was estimated to be endothermic and spontaneous. Reduction of U(VI) to lower valent species was confirmed by X-ray photo-electron spectroscopy analysis. It is very interesting to find that U(VI) sorption on TiO2 was promoted in solutions with higher back-ground electrolyte concentrations. In the presence of U(VI), higher back-ground electrolyte made more TiO2 particles aggregate through (001) facets, leading more (101) facets to be exposed. Therefore, the reduction of U(VI) was enhanced by the exposed (101) facets and more U(VI) removal was observed.


Asunto(s)
Sustancias Húmicas , Titanio/química , Uranio/química , Adsorción , Concentración de Iones de Hidrógeno , Iones , Modelos Químicos , Concentración Osmolar , Suelo , Temperatura , Titanio/análisis
11.
Water Sci Technol ; 74(8): 1800-1808, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27789881

RESUMEN

Commercial pulverous activated carbon (AC-0) was modified through two steps: oxidize AC-0 acid firstly, impregnate it with iron using ferric chloride secondly. Orthogonal experiment was conducted then to prepare modified activated carbon with high Cd(II) adsorption capacity (ACNF). Batch adsorption experiments were undertaken to determine the adsorption characteristics of Cd(II) from aqueous solution onto AC-0 and ACNF and the effect of pH, contact time and initial Cd(II) concentration. The results indicate that: the adsorption behavior of Cd(II) on ACNF can be well fitted with Langmuir model, and the maximum adsorption capacity of ACNF was 2.3 times higher than that of AC-0, supporting a monolayer coverage of Cd(II) on the surface. The kinetics of the adsorption process can be described by pseudo-second-order rate equation very well, and the adsorption capacity increased from 0.810 mg/g to 0.960 mg/g after modification. Compared with AC-0, the kinetic parameters of ACNF showed a higher adsorption rate through the aqueous solution to the solid surface and a lower intraparticle diffusion rate. Surface modification resulted in a lower Brunauer-Emmett-Teller (BET) surface area and pore size because of the collapse and blockage of pores, according to the X-ray diffraction (XRD) analysis, while the total number of surface oxygen acid groups increased, and this was supposed to contribute to the enhanced adsorption capacity of modified activated carbon.


Asunto(s)
Cadmio/química , Carbón Orgánico/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Adsorción , Cinética , Nitrógeno/química
12.
Guang Pu Xue Yu Guang Pu Fen Xi ; 36(10): 3442-8, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30247006

RESUMEN

In virtue of the severity and scale of the pollution caused by oil pool flame, space remote sensing can provide us a new way of monitoring in real time the oil pool flame pollution. Space remote sensing monitoring is based on the analysis of target spectrum characteristics. Due to lack of adequate researches on the characteristics of infrared spectrum of oil pool flame, this paper carries out the analytical study on flame spectrums of several types of oil, mixed oil and other combustible objects in outdoor space by establishing all-flame infrared testing system with the spectrum range of 1~14 µm. The results show that the spectrum curves of oil pool flame of 92# gasoline, 95# gasoline, 0# diesel, aviation kerosene and lube have similar features, that there exist characteristics emission peaks at the area of certain wave lengths­H2O characteristics emission peak for 1.1, 2.4, 2.8 and 6.3 µm, CO2 characteristics emission peak for 4.2 and 4.5 µm, C­H stretching vibration emission peak for 3.4 µm, and no obvious characteristics peak for spectrum curves of 6.3 µm and above; that there is no obvious difference in the spectrum of oil pool flame among the mixtures of 92# gasoline and 0# diesel at different proportions, that the comparison of the flame spectrum of 92# gasoline with that of wood and paper shows that there appears a characteristics emission peak at 3.4 µm; that though the flame spectrum of alcohol has similar radiated emission near 3.4 µm, the proportion of its radiation intensity to that of CO2 at 4.5 µm is far less than that for the flame spectrum of 92# gasoline; that the flame spectrum of honeycomb briquette is similar to that of gray body radiation. The differences in flame spectrum among all kinds of combustible materials are closely linked to their chemical compositions and burning reaction mechanisms. Comparative analysis on the spectrum characteristics at continuous area, intermission area and flue gas area shows that C­H stretching vibration peak only exists in continuous area, which proves that the emission peak is caused by the combustible reaction of oil and gas. This result is in line with the mechanism of oil pool combustion reaction. The experimental conclusion is of great significance in the remote-sensing recognition of oil pool flame based on the analysis of spectrum characteristics.

13.
J Phys Ther Sci ; 28(7): 2027-30, 2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-27512257

RESUMEN

[Purpose] This study investigated the clinical efficacy of the compound gouteng tincture combined with Zhoubo (GT-ZB) in treating the sequelae of cerebral concussion (CC) in children. [Subjects and Methods] Sixty children with CC-sequelae were randomily divided into a treatment group and a control group, with 30 cases in each group. The treatment group was treated using GT-ZB, and the control group was treated using the standard method of venoruton, dibazol, and Vitamin B6. The efficacies of the two treatments were compared. [Results] Compared with the control group, the clinical symptoms and signs in the treatment group were significantly mitigated. [Conclusion] GT-ZB demonstrated efficacy in treating the sequelae of CC in children, and it is worthy of further studies and possible clinical recommendations.

14.
Guang Pu Xue Yu Guang Pu Fen Xi ; 34(5): 1234-9, 2014 May.
Artículo en Zh | MEDLINE | ID: mdl-25095413

RESUMEN

Cationic Polyacrylamide P(AM-DAC-BA) was synthesized by UV initiation, with acrylamide (AM), acryloyloxyethyl trimethyl ammonium chloride (DAC), butyl acrylate (BA) as the monomers. P(AM-DAC-BA). UV spectroscopy and infrared spectroscopy were employed to study the structural characteristics. Attributions of typical infrared vibrational frequencies in AM/DAC/BA/P(AM-DAC-BA) were analysed. By comparing with infrared spectroscopy of the monomers, symmetrical characteristic of P(AM-DAC-BA) increasesd, and the infrared spectroscopy of polymerization product was simpler. The intrinsic viscosity increased with the increase in light intensity, BA content, photoinitiator concentration and illumination time. The groups of -CONH2, -COOCH2(C=O), -COOCH2--(C-O-C), -CH2--N(CH3 )3 group in AM, DAC, BA were selected as characteristic absorption peaks for studying. With the increase in light intensity and BA content, the characteristic peak areas increased. With the increase in photoinitiator concentration, the characteristic peak areas decreased. The characteristic peak areas decreased firstly and then increased with increasing the illumination time. But the corresponding characteristic IR absorption peaks of P(AM-DAC-BA) were similar, and the positions of characteristic peaks were basically the same.

15.
Water Res ; 251: 120994, 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38277825

RESUMEN

Biochar has attracted significant attention due to its excellent environmental benefits and extensive applications. Recently, a consensus has been accepted that biochar can act as a photocatalyst and trigger effective photocatalytic reactions in the environment, which is important to energy conversion and the cycle of elements. However, its photocatalytic processes and the corresponding environmental impacts need to receive more and due attention. In this review, we provide a comprehensive summary of the underlying correlations among the pyrolytic evolution of biomass, the structure characteristic of biochar, and the resultant photocatalytic performance. Moreover, the photocatalytic processes and the influence of environmental factors were elaborately investigated on biochar. Finally, future tendencies and challenges in the photocatalysis of biochar have been prospected in the environmental field. This review has offered innovative insights into the photocatalytic essential of biochar and highly enhanced the understanding of its environmental impact.


Asunto(s)
Carbón Orgánico , Carbón Orgánico/química , Biomasa
16.
Pharm Biol ; 51(8): 1021-5, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23738775

RESUMEN

CONTEXT: Podocarpium podocarpum (DC.) Yang et Huang (Leguminoseae) is a very important Podocarpium species with significant anti-inflammatory, analgesic and anti-pyretic activities, which has not yet been subjected to adequate phytochemical investigation. OBJECTIVE: To isolate and identify bioactive compounds from P. podocarpum. MATERIALS AND METHODS: Ethanol extract of the whole plant of P. podocarpum was subjected to repeated column chromatography. Chemical structures of the compounds were identified by 1D, 2D-NMR spectra and MS data. Human cervical carcinoma (HeLa) and pancreatic carcinoma (PANC-1) cell lines were employed to evaluate the in vitro cytotoxic activity of the isolated constituents at six concentrations (0.001, 0.01, 0.1, 1.0, 10.0, 100.0 µg/ml). RESULTS: A new phenylpropanoid glycoside, podocarioside A (1), together with four known compounds, (E)-3-(4-hydroxy-3-propoxyphenyl) acrylic acid (2), schizandrin (3), dehydrodiconiferyl alcohol (4) and dihydrodehydrodiconiferyl alcohol (5), were isolated from P. podocarpum. Compounds 1, 3 and 4 showed moderate cytotoxic against HeLa cells with IC50 values of 38.62, 8.64 and 5.85 µg/mL, respectively, while none exhibited toxicity against PANC-1 cells. DISCUSSION AND CONCLUSION: This is the first report on the isolation and identification of bioactive compounds from P. podocarpum. In vitro cytotoxic assay of the isolated constituents establishes the potential of those components as antitumor agents.


Asunto(s)
Antineoplásicos Fitogénicos/farmacología , Fabaceae/química , Extractos Vegetales/farmacología , Antineoplásicos Fitogénicos/administración & dosificación , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Femenino , Glicósidos/aislamiento & purificación , Glicósidos/farmacología , Células HeLa , Humanos , Concentración 50 Inhibidora , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/patología , Fenoles , Extractos Vegetales/administración & dosificación , Neoplasias del Cuello Uterino/tratamiento farmacológico , Neoplasias del Cuello Uterino/patología
17.
Adv Sci (Weinh) ; 10(5): e2205542, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36511158

RESUMEN

The photocatalytic conversion of soluble U(VI) into insoluble U(IV) is a robust strategy to harvest aqueous uranium, but remains challenging owing to the intermittent availability of solar influx and reoxidation of U(IV) without illumination. Herein, a dual platform based on K+ and cyano group co-decorated poly(heptazine imide) (K-CN-PHI) is reported that can drive persistent U(VI) extraction upon/beyond light. K-CN-PHI achieves the photocatalytic reduction of U(VI) with a reaction rate of 0.89 min-1 , being 47 times greater than that over pristine carbon nitride (PCN). This system can further be triggered by light to form long-living radicals, driving the reduction of U(VI) in the dark for over 3 d. The flexible structural K+ as counterions stabilize the electrons trapped by cyanamide groups, enabling the long lifetime of the generated radicals. The results collectively prove K-CN-PHI to be a novel and efficient photocatalyst enabling persistent U(VI) extraction around the clock, and broadening the practical applications of the photocatalytic extraction of U(VI).

18.
Chemosphere ; 311(Pt 2): 137136, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36343728

RESUMEN

Clarifying the reaction process and specific mechanism between variable-valence elements and oxidized carbon nanoparticles is essential to evaluate the environmental impact of carbon nanomaterials. In this study, the photocatalytic reduction of Cr(VI) on oxidized carbon nanotubes (OCNTs), oxidized graphene ribbons (OGRs), and graphene oxide sheets (GOs) was explored by batch experiments and spectroscopic analyses. The reaction efficiencies strongly depended on the number of oxygenated groups in the oxidized carbon nanoparticles. The abundant oxygenated groups enabled the GOs to exhibit the highest photocatalytic activity, followed by the OGRs and OCNTs. As a result, the photoreduction efficiency of Cr(VI) reached 96% for GOs, whereas those of OGRs and OCNTs were only 40% and 13%, respectively. In addition, different types of oxygenated groups exhibited various activities based on molecular model tests, following the sequence carboxylic > hydroxyl > carbonyl > ether > aldehyde > edge. Based on the underlying relationship between the oxygenated groups, topological structures, and mechanical strain in the carbon nanoparticles, we speculate that mechanical strain plays a critical role in the formation of oxygenated groups, thereby regulating their photocatalytic activities. The findings in this work provide novel insights into the roles of oxygenated groups and the mechanical strain of carbon nanoparticles in their environmental behavior.

19.
Water Res ; 238: 119918, 2023 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-37121199

RESUMEN

The environmental behavior of radioactive cesium (RCs) in contaminated areas is generally governed by soil and sediment components and natural weathering conditions. In this study, desorption tests and spectroscopic approaches were used to explore the interaction between the weathering of micaceous minerals (i.e., biotite and phlogopite) and the adsorption of Cs+ and the critical role of weathering in the environmental behavior of RCs. Results showed that the reaction sequence between weathering and Cs+ adsorption significantly affected the surface species of Cs+ and the structure of biotite and phlogopite. Regardless of whether it occurred before, after, or during Cs+ adsorption, weathering generated more high-affinity adsorption sites, namely, interlayer sites (ITs) and frayed edge sites (FESs), to different extents, and then facilitated the uptake of Cs+ at FESs and ITs on micaceous minerals in a poorly exchangeable state. Cs+ stabilized the micaceous mineral structure once it was absorbed within collapsed interlayers by hindering cation exchange and preventing further destruction during weathering. As important weathering factors, high temperature and Ca2+ content promoted the binding of Cs+ in the interlayers of biotite and phlogopite by enhancing interlayer cation exchange. These findings are beneficial for a better understanding of the environmental behaviors of RCs in the hydrosphere and pedosphere.


Asunto(s)
Radioisótopos de Cesio , Cesio , Adsorción , Cesio/análisis , Minerales/química , Silicatos de Aluminio
20.
Sci Total Environ ; 862: 160872, 2023 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-36521591

RESUMEN

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 (Kow) of different PAHs. The adsorption kinetic and isotherm were well fitted by Pseudo-second-order kinetic model, Freundlich and Linear isotherm model. Furthermore, inorganic ions (Ca2+) impacted PAHs adsorption by competitive adsorption and cation-π interactive. Cal has the maximum desorption of PAHs among three minerals, and there was desorption hysteresis phenomenon. Field emission-scanning electron microscope (Fe-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) analysis indicated that SOM enhanced the sorption of PAHs by van der Waals, hydrogen bonding, π-π interactions, and chemical bonding. LMWOAs significantly inhibited PAHs adsorption and promote PAHs desorption from the minerals. As a result, LMWOAs increased of PAHs bioavailability, which provide a new strategy to improve PAHs cleanup efficiency.


Asunto(s)
Fenantrenos , Hidrocarburos Policíclicos Aromáticos , Peso Molecular , Minerales , Hidrocarburos Policíclicos Aromáticos/análisis , Bentonita/química , Suelo , Caolín , Carbonato de Calcio , Adsorción
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