Abstract
Catalysts prepared by co-precipitation of iron and titanium were evaluated in heterogeneous photo-Fenton degradation of the azo dye Acid Red 8 under blacklight irradiation. Materials with different titanium contents (0 < Ti/Fe < 0.6) were characterized using X-ray diffractometry, scanning electron microscopy, X-ray fluorescence spectroscopy, specific surface area and X-ray photoelectron spectroscopy. Hematite was identified as main phase in materials with lowest Ti content, while titanomaghemite was predominant at high Ti content. Highest degradation was obtained using titanium free catalyst due to iron leaching, which promoted a homogeneous reaction. Addition of Ti led to a heterogeneous process with a maximum when Ti/Fe = 0.40 achieving 0.76 mol of dye mineralized per mol of soluble iron after 90 min, using 10 mmol L-1 H2O2 at pH 5.6, value at least three times higher than that observed for catalysts with lower Ti content. The results indicate that Ti stabilizes the catalyst and increases its heterogeneous activity in photo-Fenton process.
Highlights
Among the remediation processes for aquatic pollutants removal, the classical homogeneous Fenton system is a powerful source of oxidative HO (E0 = 2.80 V/SHE) generated from decomposition of H2O2 in the presence of Fe2+ ions.[1,2] It is one of the most effective advanced oxidation processes (AOP) and widely studied for efficient treatment of industrial wastewater containing nonbiodegradable organic pollutants
The positions and relative intensities of the X-ray diffraction (XRD) peaks correspond in good agreement with the JCPDS (Joint Committee on Powder Diffraction Standards) database to α-hematite (α-Fe2O3, JCPDS 73-606) for the titanium free catalyst (CAT1)
With the increase of Ti content to Ti/Fe = 0.22 (CAT2) there is a change in the structure evidencing besides α-hematite phase the presence of titanium and iron oxide (JCPDS 89‐2812)
Summary
Among the remediation processes for aquatic pollutants removal, the classical homogeneous Fenton system is a powerful source of oxidative HO (E0 = 2.80 V/SHE) generated from decomposition of H2O2 in the presence of Fe2+ ions.[1,2] It is one of the most effective advanced oxidation processes (AOP) and widely studied for efficient treatment of industrial wastewater containing nonbiodegradable organic pollutants. Drawbacks such as the requirement of a low pH and a significant amount of ferric hydroxide sludge formed during the treatment have limited its application in homogeneous medium.[3,4]. The spectra were deconvoluted using Voigt profiles formed by the combination of Gaussian and Lorentz curves using the CasaXPS software.[26]
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