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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.

This study focuses on the preparation and performance of an innovative, novel supported TiO2 photocatalyst to fix TiO2 Degussa P25 on Raschig glass rings. An interfacial electrostatically charged agent polyethylene−graft−maleic anhydride is used as a binder for the TiO2. This photocatalyst presented a stable performance during the degradation of phenolic waters. The photodegradation process was investigated as a function of (i) the concentration of the electron acceptor (H2O2), (ii) the intensity of the applied light, and (iii) the recirculation of the wastewaters in the photoreactor. The TiO2 catalyst was observed to maintain the pH at values close to 7 during the reactor treatment, enabling the treated phenolic waters to be discharged directly to a biological treating station. Modeling of the phenolic waters degradation was conducted through a single-exponential polynomial function. This gives a systematic way to determine the most economic use of the oxidant (H2O2) and electric energy required for the degradation process.

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