Highly dispersed PTFE/Co3O4 flexible films as photocatalyst showing fast kinetic performance for the discoloration of azo-dyes under solar irradiation

Abstract

Small nanosized clusters of Co 3 O 4 coated on PTFE (polytetrafluoroethylene) flexible film is reported as a novel supported photocatalyst effective in the fast discoloration of the azo-dye Orange II under simulated solar radiation in the presence of oxone (2KHSO 5 ·KHSO 4 ·K 2 SO 4 ). The photocatalytic discoloration of Orange II on the PTFE/Co 3 O 4 films proceeds within minutes and the process could be repeated many times without a loss in photocatalyst stability. The photodiscoloration proceeds with a photonic efficiency of ∼1. The PTFE seems to act as a structure forming matrix for the colloidal Co 3 O 4 coated on it surface leading to nanosized clusters of Co 3 O 4 . Monitoring the amount of Co 2+ -ions shows the Co 2+ -ions from the PTFE/Co 3 O 4 during the photocatalysis enter the solution and at a later are stage re-adsorbed the Co 3 O 4 crystallographic network (∼8 min). By elemental analysis (EA) the loading of Co-loading per cm 2 PTFE film was found to vary between 1% and 2%. Transmission electron microscopy (TEM) shows the size of the Co 3 O 4 clusters to vary between 3 and 10 nm. Electron dispersive spectrometry (EDS) confirms the presence of Co on the PTFE. X-ray photoelectron spectroscopy (XPS) of the PTFE/Co 3 O 4 films reveal a partial reduction of the Co 3 O 4 after Orange II discoloration leading to a substantial increase of the amount of Co(II) species in the Co 3 O 4 . Physical insight is provided into the catalyst film surface by carrying out Ar-sputtering of the PTFE/Co 3 O 4 surface to remove the catalyst overlayers up to ∼20 nm.

Comparative investigation of the formation of polytetrafluoroethylene nanoparticles on different solid substrates through the adsorption of tetrafluoroethylene

“…Commonly solid substrates with higher surface roughnesses, such as CNFs, provide stronger interactions with the adsorbed species 42, 43. Therefore, the presence of plenty of adsorptive sites in the structure of nanomaterials such as CNFs causes the adsorption of large amounts of TFE 42, 43. In this study, the results attained from various analytical techniques were in good agreement with the degree of the defect extent of nanostructures such as CNFs.…”

“…Thus, the adsorptive capability of the solid support was influenced by the defect extent of the nanostructures as the solid support during the formation of PTFE. Commonly solid substrates with higher surface roughnesses, such as CNFs, provide stronger interactions with the adsorbed species 42, 43. Therefore, the presence of plenty of adsorptive sites in the structure of nanomaterials such as CNFs causes the adsorption of large amounts of TFE 42, 43.…”

Hollow cobalt phosphonate spherical hybrid as high-efficiency Fenton catalyst

“…[10][11][12][13][14] For homogeneous reactions, the activation of PMS by cobalt ions leads to the generation of sulfate radicals, which possess more powerful oxidizing ability toward the decomposition of organic molecules as compared to hydroxyl radicals due to the higher standard reduction potential of reactive radicals. [15][16][17] Thus, cobalt ion/PMS catalytic systems provide a suitable alternative to convenient Fenton reagent for contaminant oxidation. However, it is noteworthy that the use of cobalt ions in the conventional homogeneous reaction raises a toxicity issue and can further increase the health concern and contribute to an increase in pollution.…”

Photocatalytic Membranes in Degradation of Organic Molecules

“…Following we have summarized recent development of PVDF photocatalytic membranes in degradation of organic pollutants (Table 4). Recently, there have been many reports of using modified poly(tetrafluoroethylene) (PTFE) fiber and membranes for the degradation of dyes [129,130]. Modified PTFE fibers by acrylic acid and loaded Fe 3+ were prepared and used as Fenton catalysts for the degradation of reactive Blue 222 in the pH range 3-9 under visible irradiation [131].…”