RESUMO
The revelation of MoS2as an efficient electromagnetic wave (EMW) absorbing material has ratcheted up people's attention to other transition metal dichalcogenides (TMDs). To date, extensive studies have been conducted on the semiconducting VIB-Group TMDs while research into metallic VB-Group TMDs has been relatively rare. In this work, we successfully fabricated VB-Group VSe2microspheres through a facile one-step hydrothermal method and used them as EMW absorbers. The flowerlike VSe2microspheres based on VSe2nanosheets exhibited a minimum reflection loss of 46.58 dB with an effective absorption bandwidth of 4.86 GHz. The influence of material morphology, microstructure, and dielectric properties on the EMW absorption performance was systematically investigated. The hierarchically layered structure promoted dielectric loss and EMW absorption by means of multiple reflection, interfacial polarization and related relaxation, and enhanced attenuation ability. This work not only demonstrates that VSe2is potentially a high-efficiency single component EMW absorber, but also provides fresh insights into exploration on the EMW loss mechanisms of the metallic TMD-based absorbing materials.
RESUMO
Hexavalent chromium (VI) heavy metal contamination is considered a serious threat to human health and the environment. The photocatalytic reduction of Cr(VI) basically occurs in the acidic environment, severely limiting the application of photocatalysts for the reduction of Cr(VI). Therefore, we designed a microenvironment strategy to achieve efficient reduction of Cr (VI) under neutral conditions by introducing sulfonic acid onto the aromatic conjugated skeleton. A series of characterizations and experiments have shown that the sulfonated aromatic ring conjugated polymer (Arcp-SO3H) can efficiently remove Cr(VI) under neutral or even alkaline conditions. In neutral solutions, Arcp-SO3H has a rate constant of 0.054 min-1 within 90 min and has an efficiency of nearly 100 %, which is 16 times faster than before sulfonation (k = 0.0316 min-1). the Arcp-SO3H surpasses all organic polymers and most metal-based photocatalysts in the related field. The capture experiments have proved that â¢O2- is the main role of reducing Cr(VI), and e- is secondary, which is quite different from the mechanism reported in the previous literature. The efficiency of reducing Cr (VI) in the four-cycle experiment is still 96 %, which also proves that Arcp-SO3H has strong stability and reproducibility. Thus, Arcp-SO3H has great practical application potential in the treatment of wastewater, and microenvironmental strategies also offer new possibilities in the field of environmental remediation.
Assuntos
Recuperação e Remediação Ambiental , Polímeros , Humanos , Reprodutibilidade dos Testes , CromoRESUMO
Magnetic nanoparticle materials which could be used to remove tetracycline were confined seriously due to their poor stability and unsatisfactory reusability. Here, we facilely prepared novel zeolitic imidazolate framework-8 (ZIF-8) functionalized magnetic nanoparticles (Fe3O4@PDA-ZIF-8) adsorbent utilizing polydopamine as a bond to establish a connection between zeolitic imidazolate framework-8 and Fe3O4, which could improve the stability of magnetic nanoparticles and enhance the tetracycline adsorption capacity simultaneously. The prepared nanocomposites were characterized and their TC adsorption abilities under various experiment conditions (contact time, TC initial concentration and pH values) were also investigated. Experimental results proved that the prepared adsorbent showed superior TC adsorption capacities (92.01 mg/g at pH = 7). Further, the adsorption mechanisms were comprehensively studied and the prepared adsorbent showed satisfactory stability and reusability during the cycle experiment. Altogether, our findings provided a feasible way to design and construct functional magnetic MOF materials for enhancing tetracycline adsorption from wastewater.