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1.
J Am Chem Soc ; 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-32207939

RESUMO

Here we propose a strategy of radical oxidation reaction for the high-efficiency production of graphene oxide (GO). GO plays important roles in the sustainable development of energy and the environment, taking advantages of oxygen-containing functional groups for good dispersibility and assembly. Compared with Hummers' method, electrochemical exfoliation of graphite is considered facile and green, although the oxidation is fairly low. To synthesize GO with better crystallinity and higher oxidation degree, we present a photosynergetic electrochemical method. By using oxalate anions as the intercalation ions and co-reactant, the interfacial concentration of hydroxyl radicals generated during electrochemical exfoliation was promoted, and the oxidation degree was comparable with that of GO prepared by Hummers' method. In addition, the crystallinity was improved with fewer layers and larger size. Moreover, the aniline coassembled GO membrane was selectively permeable to water molecules by the hydrogen-bond interaction, but it was impermeable to Na+, K+, and Mg2+, due to the electrostatic interactions. Thus, it has a prospective application to water desalination and purification. This work opens a novel approach to the direct functionalization of graphene during the electroexfoliation processes and to the subsequent assembly of the functionalized graphene.

2.
ACS Appl Mater Interfaces ; 11(33): 29736-29745, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31343862

RESUMO

Zirconium oxide (ZrO2) nanoadsorbents exhibit great potential in the remediation of arsenic-polluted water. However, physicochemical structure-adsorption performance relationship is not well-understood, which retards further development of high-performance ZrO2 nanoadsorbents. Herein, a facile-controlled crystallization strategy was developed to synthesize defective ZrO2 with the assistance of organic ligands. Systematic characterizations showed that this proposed synthesis strategy can be exploited to regulate the defective density of ZrO2, whereas other structural properties remain almost unchanged. Batch adsorption experiments exhibited that UiO-66-SH-A with a higher lattice defect possessed a larger capacity and a faster rate for the uptake of As(III)/As(V). The maximum capacities of UiO-66-SH-A to uptake As(III) and As(V) were up to 90.7 and 98.8 mg/g, respectively, which are 12.3 and 11.5 times larger than those of UiO-66-A. These results from the structure-performance analysis and theoretical calculations further reveal that lattice defect plays a key role in the enhancement of arsenic adsorption on ZrO2. We hope this new understanding of the structure-dependent adsorption performance will provide a valuable insight for designing Zr-based nanoadsorbents to capture arsenic.

3.
J Environ Manage ; 237: 63-74, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30784867

RESUMO

Magnetic iron-titanium binary oxide as an effective adsorbent for arsenic contaminant is a challenge primarily because of their bulk structure and agglomeration effect. Herein, a novel and uniform sandwich-like magnetic Fe3O4@TiO2 sheets were synthesized by utilizing a facile strategy involving amorphous-to-crystalline transformation and reduction in H2, to achieve dispersed anatase TiO2 nanoparticles with a small size of ∼8 nm anchored on Fe3O4 sheets. The resultant Fe3O4@TiO2 sheets nanocomposite possessing a high specific surface area of ∼89.4 m2 g-1 and available magnetic susceptibility of ∼20.0 emu g-1, significantly enhanced the photocatalytic oxidation property of arsenite and considerable adsorption capability for arsenic removal. The adsorption capacities of As(V) and As(III) with UV-assisted from adsorption experimental results were 36.36 and 30.96 mg g-1, respectively, while the residual concentrations for both As(V) and As(III) were lower than the strict limit of 10 µg L-1. Adsorption equilibriums were almost reached within 45 min. In addition, the adsorbent exhibited excellent stability over a broad pH range of 3-9 and still maintained great removal efficiency after five time regeneration cycles. Furthermore, except for silicate and phosphate, the extremely weak inhibiting influences of common co-existing ions in arsenic removal process, demonstrated that the developed magnetic Fe3O4@TiO2 sheets with unique nanostructure could be a promising efficient adsorbent for arsenic removal.


Assuntos
Arsênico , Nanopartículas , Poluentes Químicos da Água , Purificação da Água , Adsorção , Concentração de Íons de Hidrogênio
4.
Nanoscale ; 11(7): 3311-3317, 2019 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-30720804

RESUMO

Self-recoverable Pd-Ru/TiO2 nanocatalysts have been prepared by electrochemical stripping of Pd-Ru/TiO2 precursors. For the ethanol oxidation reaction (EOR), these Pd-Ru/TiO2 nanocatalysts are used as an anode catalyst. The characterization of catalysts via chronoamperometry has been repeated 15 times. After 15 stability tests, the Pd1Ru0.69/TiO2 nanocatalysts still achieve a factor of 9.4 enhancement at the residual current density (309.42 mA mgPd-1) for the EOR over commercial Pd/C catalysts (33.01 mA mgPd-1). From the 5th to 15th test, when each 10 000 s stability test is performed in a fresh ethanol electrolyte, the initial and residual current density of the catalysts could recover to the original or even better value in a few hours before performing another 10 000 s stability test. Herein, these Pd-Ru/TiO2 nanocatalysts with ultrastability towards ethanol electrooxidation are self-recoverable. Density functional theory calculations reveal that the introduction of oxophilic metal Ru and a TiO2 support into Pd-based catalysts and the synergistic effects between Ru and TiO2 have led to the ultrastability towards the EOR. The introduction of oxophilic metal Ru and a TiO2 support into catalysts can reduce the adsorption energy of OHads on the Pd-Ru/TiO2 nanocatalysts, and it will inhibit the COads produced and adsorbed on the Pd surface.

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