Photodegradation of Phenol, 2-Chlorophenol and o-Cresol by Iron Oxide Nanoparticles

Iron oxide nanoparticles were prepared by mixing either aged iron(II) or aged iron(III) hydrated chlorides with hydrogen peroxide at pH 4.20.1. 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 3.80.1. 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.