University of Madeira

About: University of Madeira is a education organization based out in Funchal, Portugal. It is known for research contribution in the topics: Population & Dendrimer. The organization has 1014 authors who have published 2759 publications receiving 59457 citations.

Enhanced decoloration efficacy of electrospun polymer nanofibers immobilized with Fe/Ni bimetallic nanoparticles

Abstract: Colloidal Fe/Ni bimetallic nanoparticles (NPs) have been applied as important materials for environmental remediation applications; however, the reusability of the colloidal Fe/Ni NPs still remains a great issue that limits their environmental applications. In this paper, we developed two different routes to synthesize and immobilize Fe/Ni bimetallic NPs using electrospun polyacrylic acid/polyvinyl alcohol nanofibers as nanoreactors: (1) synthesis of Fe NPs followed by post-coating Ni on Fe NPs (referred to post-coated Fe/Ni NPs) and (2) co-reduction of nickel and iron precursors within the nanofibers (referred to co-reduced Ni/Fe NPs). The formed electrospun nanofibrous mats containing Fe/Ni bimetallic NPs were characterized via different techniques. The decoloration efficiency of the two kinds of Fe/Ni NP-containing nanofibrous mats was compared with that of single metal zero-valent iron NP-containing nanofibrous mats. We show that the co-reduced Fe/Ni NP-containing nanofibrous mats have much higher decoloration efficiency than the single iron NP-immobilized polymer mats; whereas the mats containing post-coated Fe/Ni NPs have lower decoloration efficiency than the single iron NP-containing mats. The formed co-reduced Fe/Ni NP-containing polymer nanofibers can be reused for at least 4 times with high decoloration efficiency. With the easiness of formation and convenient reusability and recyclability, the bimetallic NP-containing polymer nanofibers could be applied in different potential applications including environmental remediation, fuel cells, and electrochemical sensors.

Comparing two non-equilibrium approaches to modelling of a free-burning arc

Abstract: Two models of high-pressure arc discharges are compared with each other and with experimental data for an atmospheric-pressure free-burning arc in argon for arc currents of 20–200 A. The models account for space-charge effects and thermal and ionization non-equilibrium in somewhat different ways. One model considers space-charge effects, thermal and ionization non-equilibrium in the near-cathode region and thermal non-equilibrium in the bulk plasma. The other model considers thermal and ionization non-equilibrium in the entire arc plasma and space-charge effects in the near-cathode region. Both models are capable of predicting the arc voltage in fair agreement with experimental data. Differences are observed in the arc attachment to the cathode, which do not strongly affect the near-cathode voltage drop and the total arc voltage for arc currents exceeding 75 A. For lower arc currents the difference is significant but the arc column structure is quite similar and the predicted bulk plasma characteristics are relatively close to each other. (Some figures may appear in colour only in the online journal)