Coordination Kinetics of Different Metal Ions with the Amidoximated Polyacrylonitrile Nanofibrous Membranes and Catalytic Behaviors of their Complexes

Abstract

Two transition metal ions (Fe3+ and Cu2+) and a rare earth metal ion (Ce3+) were selected to coordinate with amidoximated polyacrylonitrile (PAN) nanofibrous membrane for preparing three metal modified PAN nanofibrous membrane complexes (M‐AO‐n‐PANs, M = Fe, Cu, or Ce) as the heterogeneous Fenton catalysts for the dye degradation in water under visible irradiation. The coordination kinetics of three metal ions with modified PAN nanofibrous membranes was studied and the catalytic properties of the resulting complexes were also compared. The results indicated that increasing metal ion concentrations in solution or higher coordination temperature led to a significant increase in metal content, particularly in Fe and Cu contents of the complexes. Their coordination process could be described using Langmuir isotherm and pseudo‐second‐order kinetic equations. Moreover, Fe‐AO‐n‐PAN had the best photocatalytic efficiency for the dye degradation in acidic medium, but a lower photocatalytic activity than Cu‐AO‐n‐PAN in alkali medium.

Competitive coordination of iron(III) and copper(II) ions with amidoximated polyacrylonitrile nanofiber and the catalytic performance of the complex

“…There were mutual competition and synergistic interaction between the two kinds of metal ions. In detail, the addition of Cu 2+ ions was beneficial to the increase of the coordination amount of Fe 3+ ions, while the latter had a strong competitive effect on the former, which is consistent with the coordination reaction between single metal ions and AO-n-PAN, that is, Fe 3+ ions were more prone to coordinate with AO-n-PAN than Cu 2+ ions [22].…”

“…According to our previous work [22], both Langmuir isotherm and Freundlich isotherm had high R 2 values when fitting the data from the coordination between single metal ions and AO-N-PAN, but Langmuir isotherm was relatively more suitable. However, the adsorption process of Fe 3+ -Cu 2+ binary solution by AO- n -PAN cannot be described by Langmuir or Freundlich isotherm commonly used in single metal ion systems due to the addition of competitive ions.…”

Degradation of Methylene Blue with a Cu(II)–Quinoline Complex Immobilized on a Silica Support as a Photo-Fenton-Like Catalyst

“…The catalysis takes place on the surface of the silica particles, where the active site of the [L–Cu 2+ ] complex was immobilized. The unsaturated [L–Cu 2+ ] complex could bind peroxide to form [L–Cu 2+ ( − O 2 H)] (pathway (1)), which can subsequently transform into a peroxo complex [L–Cu + (O 2 H) • ] as a result of charge transfer between a hydroperoxide anion ( − O 2 H) and Cu 2+ (pathway (2)). , The peroxo complex can then react with H 2 O 2 to produce HO • radicals (pathway (4)). − The [L–Cu 2+ ( − O 2 H)] can also be regarded as an oxidant based on a complex mechanism, directly oxidizing substrates through pathway (6). , In addition, the copper redox cycle with HO • and the production of dissolved O 2 (pathway (4)) are likely to involve a catalytic cycle (pathways (7) and (8)). ,− During these processes, the substrate in the reaction can be excited (pathway (9)), transferring an electron to the metal-centered orbitals (pathway (10)) with this substrate to the metal charge transfer (SMCT) process contributing to the decolorization of the substrate via the loss of conjugation of the double bonds in the molecule . With photo assistance, the photoreduction of Cu 2+ to Cu + occurs through charge transfer between the ligand and the metal.…”

Rhodamine B dye is efficiently degraded by polypropylene-based cerium wet catalytic materials

“…In the catalytic wet peroxide oxidation system, the change trend of the valence state of rare earth ions and the process and nature of the transformation of the stable and abnormal valences are all conducive to the production of free radicals and improve the degradation efficiency for organic pollutants. Some researchers have used rare earth elements as catalytic materials, 2 some use rare earth elements as doping elements to prepare composite metal oxide catalytic materials, 20,21 and others directly use rare earth oxides as catalysts to degrade organic pollutants. 22 All these materials exhibit more optimal removal performance.…”