Resíduos da mineração de ferro como catalisadores para a degradação de contaminantes orgânicos em água

Abstract

This work reports the use of an iron mining residue (R) containing 21.4% of Fe and 65.7% of SiO2 as heterogeneous catalyst for Fenton reaction. Moreover, the R was modified by heat treatment under CH4 (RCH4) or impregnated with PET powder residue (from bottles recycling) followed by a heat treatment under N2 atmosphere to produce a composite material (R-PET). The catalysts characterization revealed that the R is mainly composed of SiO2, hematite and goethite whereas the R-CH4 present reduced iron phase of wustite (FeO). The R-PET is composed of carbon islands (10 wt.% of carbon content) dispersed over the oxides matrix. A partial iron reduction (Fe3+  Fe2+) occurred during the thermal decomposition of PET thus forming magnetite (-Fe3O4). Catalytic tests for H2O2 decomposition showed that the modified catalysts (R-CH4 and R-PET) presented increased activity compared to pure R, possibly due to the presence of reduced iron phases, and the reaction follows a radical mechanism. The catalysts were very active for dyes oxidation (methylene blue and rhodamine B) through heterogeneous Fenton and the emergent contaminant the paracetamol drug, specially R-CH4 (MB removal > 62% and RhB and PRC removal > 90%).