Síntese de nano-híbrido magnético à base de grafeno e ferrita de cobalto como catalisador heterogêneo na degradação de bisfenol A por eletro-Fenton

Abstract

A simple, efficient, environmentally friendly, and inexpensive synthesis route was developed to obtain a magnetic nano-hybrid (GH) based on graphene and cobalt ferrite, with excellent potential for adaptation to the industrial scale. Water with a high content of natural organic matter (MON) was used as a natural solvent and as a carbon source. The composition of the material was confirmed by FTIR and RAMAN spectroscopy, which evidenced the formation of graphene, as also corroborated by XRD analyses. The diffractograms and TEM images showed the formation of a hybrid nanomaterial composed of graphene and cobalt ferrite, with crystallite and particle sizes of 0.8 and 4.0 nm, respectively. The heterogeneous electro-Fenton process (EF-GH) achieved 100% degradation of bisphenol A (BPA) in 50 min, with 80% mineralization in 7 h, at pH 7, using a current density of 33.3 mA cm-2 . Electrochemical oxidation with hydrogen peroxide electrogeneration (EO-H2O2) achieved a lower percentage 71% degradation and 58% mineralization in the same times. GC-MS analysis identified the main degradation intermediates, including 4,4'-(1-hydroxypropane-2,2-diyl) diphenol and (3)-5-(4-hydroxyphenyl)-5-methyl-4-(2-oxoethyl)hex-3-enoic acid. The high catalytic performance was achieved at neutral pH, enabling substantial reduction of the costs of treatment processes. In this way, the results obtained showed that the magnetic graphene hybrid was obtained via the exfoliation route. The material showed an excellent performance in heterogeneous catalysis for degradation of persistent organic contaminant by electro-Fenton.