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1.
J Hazard Mater ; 423(Pt A): 127104, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34523482

RESUMO

Soils contamination with Cd result in detriment to the environmental quality. In-situ immobilization methods by applying clay minerals have been gaining prominence. The effects on sepiolite of thermal activation at different temperatures (300-750 °C), for removing Cd from aqueous solutions were evaluated, in order to consider their further application for soil remediation. The influence of activation temperature was investigated using XRD, SEM, and N2 adsorption-desorption measurements. The S-600 exhibited the maximum adsorption capacity (21.28 mg/g), despite its lower SSA, and Langmuir model described the adsorption isotherms better than the Freundlich equation. TCLP was used to quantify the remediation effects of thermal-activated sepiolite on simulated soils artificially polluted with Cd. The results indicated that the mobility of Cd in soil was effectively reduced after treating with thermal-activated sepiolite and the use of S-600 was the most efficient, reducing the TCLP-Cd by approximately 73% compared with the control test. The main remediation mechanism was considered as the cation exchange of Cd by Mg at the edges of octahedral sheet. This study showed that thermal-activated sepiolite could be promising amendments for remediation of Cd-contaminated soil.

2.
J Mater Chem B ; 9(2): 404-409, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33283827

RESUMO

Montmorillonite (MMT), as a naturally sourced and FDA-approved biomaterial, has attracted considerable attention due to its extensive application in biomedical areas, such as intestinal ailments, drug delivery, and additive manufacturing. In this work, two-dimensional montmorillonite (2D-MMT) ultrathin nanosheets were successfully prepared from sodium montmorillonite (Na-MMT) by utilizing a freeze-drying assisted method. Possessing a large specific surface area and increased number of exposed hydroxyl groups, 2D-MMT nanosheets exhibited better antibacterial ability than the original Na-MMT. More strikingly, we found that both 2D-MMT nanosheets and Na-MMT could generate reactive oxygen species (ROS) upon visible light illumination, which could promote their antibacterial efficiency. As a result, 2D-MMT nanosheets showed efficient antibacterial performance in the presence of light towards Escherichia coli with a simultaneous enhancement of surface adsorption and photodynamic ablation. What's more, a possible mechanism for ROS generation by MMT upon light illumination was first proposed in this work. The combination of the increased physical adsorption capacity and ROS generation ability of 2D-MMT nanosheets would help inspire the development of MMT as a promising antimicrobial candidate in the future.


Assuntos
Antibacterianos/metabolismo , Bentonita/química , Nanotecnologia/métodos , Fotoquimioterapia/métodos , Humanos , Espécies Reativas de Oxigênio
3.
Nanoscale ; 11(43): 20715-20724, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31642836

RESUMO

Developing advanced lithium-ion hybrid capacitors (LIHCs) has a critical challenge of matching kinetics and capacity between the battery-type anode and the capacitive cathode. In this work, a novel "dual carbon" LIHC configuration is constructed to overcome such a discrepancy. Specifically, hollow nitrogen-doped carbon nanoboxes (HNCNBs) are synthesized by a simple template-assisted strategy. As an anode material (0.01-3 V vs. Li/Li+), the HNCNB electrode exhibits high specific capacity (850 mA h g-1 at 0.1 A g-1) and superior rate capability (321 mA h g-1 at 20 A g-1). After alkaline activation, the HNCNBs become highly porous (PHNCNBs), which offers better capacitance performance within the potential window from 2.5 to 4.5 V (vs. Li/Li+) than commercial activated carbon (AC). Coupling a pre-lithiated HNCNB anode with a PHNCNB cathode forms a dual-carbon LIHC. Since the similar hollow structure in both electrodes could diminish the diffusion distance, the as-prepared HNCNB//PHNCNB LIHC provides high energy densities of 148.5 and 112.1 W h kg-1 at power densities of 250 and 25 000 W kg-1, respectively, together with long-term cycling stability, which efficiently bridges the gap between supercapacitors and lithium ion batteries. Furthermore, the self-discharge behavior and the temperature-dependent performance are also investigated.

4.
Environ Sci Pollut Res Int ; 26(10): 9861-9875, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30734258

RESUMO

Montmorillonite grafted polyacrylic acid composite (GNM) was prepared by using ultraviolet radiation grafting method in this work. The synthesized materials were characterized by XRF, SEM, FTIR, XRD, TG, and XPS. The experimental equilibrium data indicates that the adsorbent is suitable for the Langmuir model and belongs to the pseudo-second-order kinetic model. The entire adsorption process is spontaneous, endothermic, and chaotically enhanced by thermodynamic analysis. The maximum adsorption capacity of La(III) by GNM was 280.54 mg/g at 313.15 K. In addition, the regeneration experiment shows that the adsorbent has good reusability and stable desorption efficiency. This study demonstrates that GNM has high adsorption performance and La(III) adsorption and regeneration capabilities to solve the water pollution caused by rare earth ions and regeneration capabilities for La(III).


Assuntos
Resinas Acrílicas/química , Bentonita/química , Lantânio/química , Poluentes Químicos da Água/química , Adsorção , Cinética , Termodinâmica , Raios Ultravioleta , Poluentes Químicos da Água/análise , Purificação da Água
5.
Nanoscale ; 10(37): 17814-17823, 2018 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-30221261

RESUMO

Flexible energy storage devices have become critical components for next-generation portable electronics. In the present work, a flexible quasi-solid-state lithium-ion capacitor (LIC) is developed based on graphene-based bendable freestanding films in a gel polymer electrolyte. A graphene encapsulated Fe3O4 nanocube hybrid film (rGO@Fe3O4) has been fabricated as the anode of LICs through a filtration assisted self-assembly and the subsequent thermal annealing process. In this hybrid architecture, flexible and ultrathin graphene shells uniformly enwrap the Fe3O4 within the whole film, which can effectively suppress the aggregation of Fe3O4 and also accommodate the volume change of Fe3O4 during the cycling process. As a consequence, the electrochemical performance of the rGO@Fe3O4 half-cell versus Li/Li+ shows high specific capacity (731 mA h g-1 at 0.1 A g-1), excellent rate capability (210 mA h g-1 at 10 A g-1) and superior cycling stability (98% retention after 600 cycles). After chemically etching rGO@Fe3O4 with hydrochloric acid, a holey rGO film is successfully obtained as a high-rate cathode of LICs. On the basis of such a flexible anode and cathode, the as-fabricated quasi-solid-state LIC device delivers a high energy density of 148 W h kg-1, a high power density of 25 kW kg-1 (achieved at 70 W h kg-1) and an excellent capacity retention of 82% after 2000 cycles. More importantly, the rGO@Fe3O4//holey rGO LIC shows good mechanical flexibility with stable Li-storage capacities under harsh bending.

6.
Water Sci Technol ; 77(5-6): 1570-1580, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29595159

RESUMO

In the development of industrial life, an enormous amount of silica fume (SF) has been accumulated and cannot be reused properly, and a large quantity of rare-earth elements in industrial wastewater has been inappropriately discharged, both of which pose a threat to human health and the environment. By using UV photocatalytic grafting technology, a polymer brush grafted from modified SF, which can be used as a high efficiency adsorbent, can solve both problems at the same time. Specifically, SF was firstly silanol-functionalized by γ-methacryloxypropyltrimethoxysilane (KH570), then grafted with polyacrylic acid brushes by UV photocatalytic grafting to finally obtain the adsorbent. Under optimal conditions, adsorption capacity of the adsorbent for dysprosium(III) (Dy3+) could reach 278.49 mg/g. It took 1 min for the adsorbent to reach adsorbing equilibrium at a relatively low concentration of Dy3+ (40 mg/L), and only 3 min at a medium and high concentration (130 mg/L and 200 mg/L). After six adsorption-desorption cycles, the adsorbent still possessed high adsorption capacity for Dy3+ (251.20 mg/g). The adsorption behavior of the adsorbent fit the Langmuir isotherm model (R2 > 0.97) and pseudo-second-order kinetic model (R2 > 0.98) well. The functional group of carboxylate anion, -COO-, played a central role during the adsorption process, which was verified by Fourier transform infrared and X-ray photoelectron spectroscopy analyses.


Assuntos
Disprósio/química , Resíduos Industriais/análise , Dióxido de Silício/química , Águas Residuárias/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/química , Purificação da Água/métodos
7.
Int J Biol Macromol ; 108: 1199-1206, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29126940

RESUMO

A novel effective cellulose-based adsorbent was prepared through two common reactions, which included the esterification of sugarcane bagasse cellulose with excess stearic acid and the reaction of grafting polyacrylamide brush by ultraviolet radiation initiation. The adsorbent can effectively adsorb Hg(II) ion from wastewater. The characterization of the adsorbents was conducted by optical microscope (OM), scanning electron microscopy (SEM-EDS) and infrared spectrometry (FTIR). Full kinetic and thermodynamic investigations as well as isotherm analysis were also undertaken. Due to the abundant amide groups, the cellulose-based adsorbents exhibit excellent adsorption performance for the removal of Hg(II) ion from aqueous solution with a maximum adsorption capacity of 178mg/g. Furthermore, the cellulose-based adsorbents can be easily separated from the aqueous solution after adsorption and regenerated using 0.2M HCl solution, which exhibits high adsorption capacity after six adsorption-desorption cycles. In view of the easily-operated cost-effective preparation technique, substantial adsorption efficiency and excellent adsorption recyclability, therefore, the eco-friendly cellulose-based adsorbents could be used for water purification effectively. More importantly, this work improves value of low-cost biomass resources.


Assuntos
Amidas/química , Celulose/química , Mercúrio/química , Mercúrio/isolamento & purificação , Saccharum/química , Águas Residuárias/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Soluções , Temperatura , Purificação da Água
8.
Water Sci Technol ; 75(12): 2755-2764, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28659515

RESUMO

The recovery of rare earth ions from industrial wastewater has aroused wide concern in recent years. In present work, we synthesized a novel three-dimensional adsorbent (denoted as LF-AA) by grafting loofah fiber with acrylic acid via ultraviolet radiation. The LF-AA was washed by boiling water and subjected to soxhlet extraction with acetone and then fully characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Rare earth ion (Ce(III)) was selected as a model to validate its adsorption property. The saturation adsorption capacity for Ce(III) reaches 527.5 mg/g. Not only was this material highly efficient at adsorbing Ce(III) from aqueous solutions, it also proved to have ideal performance in regeneration; the total adsorption capacity of LF-AA for Ce(III) after six successive cycles decreased only 6.40% compared with the initial capacity of LF-AA. More importantly, the LF-AA can be easily separated from aqueous solutions because of its three-dimensional sponge natural structure. This study provides a new insight into the fabrication of biomass adsorbent and demonstrated that the LF-AA can be used as excellent adsorbent for the recovery of rare earth ions from wastewater.


Assuntos
Cério/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Poluentes Químicos da Água/análise , Adsorção , Biomassa , Cério/química , Concentração de Íons de Hidrogênio , Cinética , Polimerização , Espectroscopia de Infravermelho com Transformada de Fourier , Raios Ultravioleta , Poluentes Químicos da Água/química
9.
Environ Technol ; 37(22): 2916-23, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27080358

RESUMO

Secondary coal fly ash is known as a by-product produced by the extracting alumina industry from high-alumina fly ash, which is always considered to be solid waste. Zeolitization of secondary coal fly ash offers an opportunity to create value-added products from this industrial solid waste. The influence of synthesis parameters on zeolite NaA such as alkalinity, the molar ratio of SiO2/Al2O3, crystallization time and temperature was investigated in this paper. It was found that the types of synthetic zeolites produced were to be highly dependent on the conditions of the crystallization process. Calcium ion exchange capacity and whiteness measurements revealed that the synthesized product meets the standard for being used as detergent, indicating a promising use as a builder in detergent, ion-exchangers or selective adsorbents. Yield of up to a maximum of 1.54 g/g of ash was produced for zeolite NaA from the secondary coal fly ash residue. This result presents a potential use of the secondary coal fly ash to obtain a high value-added product by a cheap and alternative zeolitization procedure.


Assuntos
Cinza de Carvão/química , Zeolitas/química , Óxido de Alumínio/química , Cálcio/química , Cristalização , Troca Iônica , Dióxido de Silício/química , Temperatura
10.
Luminescence ; 31(1): 135-40, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26014423

RESUMO

BiPO4 and Eu-doped BiPO4 crystals were synthesized via a simple precipitation route at room temperature, employing Bi(NO3)3 and (NH4)2HPO4 as the reactants, Eu2O3 as the dopant and citric acid as a template. X-ray powder diffraction analyses showed that pure rhombohedral BiPO4 form was obtained, and was the preferential orientation growth of the crystal. Field emission scanning electron microscope observations showed that the concentration of Bi(3+) obviously changed the products' morphologies from nanosphere, hollow sphere to hexagonal prism. The acidity of the solution and the contents of citric acid and Eu(3+) ion tailored the size of the final crystals. Effects of concentration of Eu(3+) ion on the luminescence emission intensity were also investigated.


Assuntos
Bismuto/química , Európio/química , Luminescência , Nanoestruturas/química , Fosfatos/química
11.
J Nanosci Nanotechnol ; 15(9): 7385-90, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26716341

RESUMO

The quality of the clays and over all halloysite are mostly associated with minor amounts of ferruginous impurities content, since this element gives an undesirable reddish color to the halloysite mineral. Hence, finding out the modes of occurrence of iron in halloysite is of prime importance in the value addition and optimum utilization of halloysite. In order to analyze the occurrence of iron impurities in halloysite, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were combined with wet chemical analysis methods to study the low-grade halloysite. The results indicated that the mineral phases of iron impurities in the concentrates are mainly composed of amounts of magnetite, goethite and hematite. Two types of occurrences for iron impurities have been found. One is single crystalline mineral consist in the halloysite, which contains three different phases of Goethite FeO(OH) (44.75%), Magnetite Fe3O4 (27.43%) and Hematite Fe2O3 (31.96%). The other is amorphous Fe-Al-Si glial materials. This study is of significance in the theoretical research on the halloysite mineralogy and in the developmental practice of halloysite in coal measures.

12.
Adv Mater ; 27(25): 3774-81, 2015 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-25995022

RESUMO

A cathode material composed of h-CNT/S/ZrO2 is developed for lithium-sulfur batteries. By incorporating ZrO2 into the S-incorporated h-CNT, permselective gateways for free Li(+) transportation can be assembled at the mesopore openings, which deny the penetration of lithium polysulfides. At the ultrahigh rate of 10 C, the discharge capacity averages to be 870 mA h g(-1) within 200 cycles.

13.
Environ Technol ; 36(17): 2168-76, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25730666

RESUMO

This work aims to investigate the adsorption of Ce(III) onto chelating resin based on activated carbon (CRAC). The CRAC adsorbent was prepared from activated carbon (AC) followed by oxidation, silane coupling, ammoniation and phosphorylation, and characterized by Fourier transform-infrared spectrometry, nitrogen adsorption measurements and scanning electron microscopy. The effects of solution pH, adsorbent dosage and contact time were studied by batch technique. Langmuir and Freundlich isotherms were used to describe the adsorption behaviour of Ce(III) by CRAC, and the results showed that the adsorption behaviour well fitted the Langmuir model. The maximum uptake capacity (qmax) calculated by using the Langmuir equation for cerium ions was found to be 94.34 mg/g. A comparison of the kinetic models and the overall experimental data was best fitted with the type 1 pseudo second-order kinetic model. The calculated thermodynamic parameters (ΔG°, ΔH° and ΔS°) showed that the adsorption for Ce(III) was feasible, spontaneous and exothermic at 25-45 °C. The CRAC showed an excellent adsorptive selectivity towards Ce(III). Moreover, more than 82% of Ce(III) adsorbed onto CRAC could be desorbed with HCl and could be used several times.


Assuntos
Cério/isolamento & purificação , Carvão Vegetal/química , Quelantes/química , Ácidos Fosforosos/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Carvão Vegetal/síntese química , Quelantes/síntese química , Concentração de Íons de Hidrogênio , Cinética , Ácidos Fosforosos/síntese química , Termodinâmica , Água/análise
14.
PLoS One ; 5(10): e13629, 2010 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-21049027

RESUMO

Two dinuclear cobalt complexes based on bis-diketonate ligands (ligand 1: 3,3'-(1,3-phenylene)bis(1-phenylpropane-1,3-dione); ligand 2: 3,3'-(1,4-phenylene)bis(1-phenylpropane-1,3-dione)) were successfully synthesized. The two neutral catalysts all showed satisfactory activities in the cobalt-mediated radical polymerization (CMRP) of methyl methacrylate (MMA) with the common initiator of azodiisobutyronitrile (AIBN). The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities. Mono- or dicomponent low polydispersity polymers could be obtained by using the two dinuclear catalysts under proper reaction conditions. All these improvements facilitate the implementation of the acrylate CMRP and open the door to the scale-up of the syntheses and applications of the multicomponent low polydispersity polymers.


Assuntos
Cobalto/química , Metilmetacrilatos/química , Polímeros/química , Catálise , Cromatografia em Gel , Cristalografia por Raios X , Estrutura Molecular
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