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1.
Inorg Chem ; 60(11): 8164-8172, 2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34014645

RESUMO

A series of benzoate-decorated lanthanide (Ln)-containing tetrameric Dawson-type phosphotungstates [N(CH3)4]6H20[{(P2W17O61)Ln(H2O)3Ln(C6H5COO)(H2O)6]}{[(P2W17O61)Ln(H2O)3}]2Cl2·98H2O [Ln = Sm (1), Eu (2), and Gd (3)] were made using a facile one-step assembly strategy and characterized by several techniques. Notably, the Ln-containing tetrameric Dawson-type polyoxoanions [{(P2W17O61)Ln(H2O)3Ln(C6H5COO)(H2O)6]}{[(P2W17O61)Ln(H2O)3}]224- are all established by four monolacunary Dawson-type [P2W17O61]10- segments, encapsulating a Ln3+ ion with two benzoates coordinating to the Ln3+ ions. 1-3 exhibit reversible photochromism, which can change from intrinsic white to blue for 6 min upon UV irradiation, and their colors gradually recover for 30 h in the dark. The solid-state photoluminescence spectra of 1 and 2 display characteristic emissions of Ln components based on 4f-4f transitions. Time-resolved emission spectra of 1 and 2 were also measured to authenticate the energy transfer from the phosphotungstate and organic chromophores to Eu3+. In particular, 1 shows an effectively switchable luminescence behavior induced by its fast photochromism.

2.
Environ Sci Pollut Res Int ; 28(2): 1889-1900, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32860603

RESUMO

In January 2012, a serious accident polluted the Longjiang River with high concentrations of cadmium (Cd) and other concomitant metals and metalloids in the water. After emergency treatment (i.e., the addition of coagulants), these metals and metalloids were transferred from the water into the sediment through precipitation of the flocculent materials produced. In this study, the long-term distribution of six metals and metalloids in the sediment of the Longjiang River was investigated and their ecological risks were assessed. Approximately 1 year after the accident (i.e., late 2012), the average Cd content in the sediment of the affected sites decreased to 25.6 ± 19.5 mg/kg, which was 8 times higher than that of 3.16 ± 3.18 mg/kg in the upstream reference sites. In 2016 and 2017, the average Cd content in the sediment of the affected sites further decreased to 4.91 ± 2.23 and 6.27 ± 4.27 mg/kg, respectively. Compared with late 2012, the amounts of Zn, Pb, and Cu obviously decreased in 2016 and 2017, whereas there were no obvious differences in the As and Hg amounts during 3 years considered. Among metals and metalloids, the average contribution of Cd to the potential ecological risk index (RI) was 90%, 69%, and 70% in the affected areas in 2012, 2016, and 2017, respectively, suggesting that Cd was the most important factor affecting the ecological risk of metals in the Longjiang River. It should be noted that the average contribution of Hg to RI in the affected areas increased from 8% in 2012 to 25% and 23% in 2016 and 2017, respectively. The sequence of contribution of six elements was Cd > Hg > As>Pb > Cu ≈ Zn. A high ecological risk of metals and metalloids was found in the sediments of two reservoirs, probably owing to the barrier effect of the dam. This study will be useful for the environmental management of rivers affected by accidental pollution of metals and metalloids.


Assuntos
Metaloides , Metais Pesados , Poluentes Químicos da Água , Acidentes , China , Monitoramento Ambiental , Sedimentos Geológicos , Metaloides/análise , Metais Pesados/análise , Medição de Risco , Rios , Poluentes Químicos da Água/análise
3.
Dalton Trans ; 49(2): 388-394, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31829355

RESUMO

Here, an organic-inorganic hybrid lanthanide-based polyoxometalate (Ln-POM) [N(CH3)4]3K2Sm(C7H5O2)(H2O)2(α-PW11O39)·11H2O (1) was successfully synthesized and characterized well by several physicochemical techniques. In the polyanion of 1, the benzoic acid ligand directly binds a Sm3+ ion for the formation of an organic-inorganic hybrid polyanion. This organic-inorganic hybrid structure can effectively sensitize the emissions of the Sm3+ ion, which was confirmed by the photoluminescence and time-resolved emission spectroscopy of 1. The photoluminescence study demonstrates that the Sm3+ ion possesses a relatively high-symmetry coordination geometry, which is consistent with the structural analysis of Sm3+ in 1. Furthermore, the polyanion of 1 can form a 3D 4,8-topology framework through the linkage of K1 and K2 ions. In addition, the photoluminescence properties of 1 have been explored, revealing that 1 shows reversible color-tunable photoluminescence based on the excitation from 260 nm to 350 nm, and emitting colors from blue to pink.

4.
Huan Jing Ke Xue ; 39(8): 3622-3630, 2018 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-29998668

RESUMO

During typhoon "Mujigae" in October 2015, water samples and surface sediments were collected from Gaozhou Reservoir, a drinking water reservoir, for simulation and analysis of the kinetics of suspended solids adsorption to nitrogen and phosphorus and the adsorption isotherms of suspended solids with different particle sizes and different concentrations. The results showed no obvious nitrogen adsorption of suspended solids of Gaozhou Reservoir. However, the adsorption effect to phosphorus by suspended solids was significant and the equilibrium time of phosphorus adsorption was 10 hours. The adsorption capacity of phosphorus increased with the decrease of sediment particle size when particle sizes were less than 0.25 mm, whereas it increased with the increase of suspended solids concentration when the concentration was in the range of 0.2-2.0 kg·m-3. The adsorption isotherm of suspended solids to phosphorus conformed to the Langmuir and Freundlich models, and the maximum adsorption capacity increased with the decrease of suspended solids particle sizes, which increased with the increase of suspended solids concentrations. The maximum adsorption capacity of suspended solids to phosphorus was 0.073-1.776 mg·g-1. These results indicated that the increase of suspended solids concentration due to the heavy rainfall of the typhoon promoted the adsorption of suspended solids to phosphorus, which reduced eutrophication in Gaozhou Reservoir.


Assuntos
Água Potável/química , Nitrogênio/química , Fósforo/química , Poluentes Químicos da Água/química , Adsorção , China , Tempestades Ciclônicas , Sedimentos Geológicos , Chuva
5.
Huan Jing Ke Xue ; 38(10): 4141-4150, 2017 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965197

RESUMO

Large-scale cyanobacteria bloom occurred in the summer of 2014 in the Guishi Reservoir that is an important drinking water source for Hezhou City. The dynamic change regularity, external pollution sources, and the phytoplankton community characteristics during the bloom were investigated to evaluate the eutrophication in the reservoir and to present effective prevention and control measures. The results showed that nitrogen and phosphorus concentrations increased year by year; water quality on some sites has been out of class Ⅱ of national water quality standards; and the main pollution source was the agricultural non-point sources. Phytoplankton cell density was in the range of 8.60×106-5.36×108 cells·L-1 and chlorophyll a concentrations reached 74.48 µg·L-1 during the bloom. The dominant species was Microcystis wesenbergii whose density reached 5.36×108 cells·L-1. The cell density decreased over time and concentrated on the surface and at the depth of 2 m underwater. The total phytoplankton cell density was strongly correlated to total phosphorus, total nitrogen, nitrate nitrogen, and the permanganate index, and was inversely correlated to transparency. The water in the Guishi Reservoir was not polluted by microcystic toxins. Moreover, Guishi Reservoir is in a meso-eutrophic state; therefore, the prevention and control of the cyanobacteria bloom should focus on weather conditions and on reducing the input of nitrogen and phosphorus to keep the nutrient levels low.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Água Potável/microbiologia , Eutrofização , Fitoplâncton/crescimento & desenvolvimento , China , Clorofila A/análise , Nitrogênio/análise , Fósforo/análise , Estações do Ano
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