Abstract

Iron oxide nanoparticles were prepared by mixing either aged iron(II) or aged iron(III) hydrated chlorides with hydrogen peroxide at pH 4.2±0.1. Iron oxide nanoparticles were identified in the mixtures of iron(II/III) chlorides with hydrogen peroxide by transmission electron microscopy (TEM) analyses. TEM analyses showed irregular sizes and the formation of different phases of iron oxide (α-Fe2O3, β-Fe2O3, γ-Fe2O3, -Fe2O3…). The variety of iron(III) oxide phases was a consequence of interactions of hydrogen peroxide with different ferric oligomers and iron oxohydroxides formed during the aging of iron(II/III) chloride mixtures. In order to decompose phenol or 2-chlorophenol or o-cresol a photocatalytic reaction was carried out in a “reactor” with iron oxide nanoparticles, visible radiation and hydrogen peroxide. Each reaction was kept at room temperature and pH 3.8±0.1. The photocatalytic processes were analyzed through UV spectrophotometry, chemical oxygen demand (COD) and total organic carbon (TOC) measurements. Iron oxide nanoparticles, in the photodegradation of phenol, 2-chlorophenol and o-cresol, presented bifunctional catalytic properties, such as a semiconductor photocatalyst and probably as Lewis acid catalyst.

Keywords: Acid lewis catalyst, ferric oligomers, heterogeneous photocatalysis, hydrogen peroxide, iron oxide nanoparticles, phenol derivatives, semiconductor photocatalyst, azo-dye, 2-chlorophenol, hydroquinone, phenol, UV radiation, radiative output, iron oxyhydroxide