A friendly environmental material: Iron oxide dispersed over activated carbon from coffee husk for organic pollutants removal

• Activated carbon was produced from coffee husk waste.
• Goethite/activated carbon composites were used in oxidation by Fenton-like process.
• Methylene blue oxidation intermediates were confirmed by ESI-MS studies.

A friendly environmental material for organic contaminants removal was prepared in this work: small particles of iron oxide dispersed over activated carbon from coffee waste for Fenton-like application. The materials were characterized by means of XRD, N2 physisorption, Mössbauer spectroscopy and H2 pulse titration. The composites showed very good catalytic performances for methylene blue organic dye oxidation. The small goethite particles are the predominant iron oxide phase in the composites. The apparent surface area is quite high and is not very affected after iron impregnation. ESI-MS studies revealed that the dye removal occurs through a Fenton-type system by the composite whereas for the activated carbon the dye removal occurs mainly via adsorption. The iron leaching from the catalysts was negligible, less than 0.5 ppm, which evidences the occurrence of a heterogenous oxidation process. The catalyst was very active for methylene blue oxidation and could be repeatedly used for at least 5 cycles. The catalyst was also active in the oxidation of other organic compounds, such as caffeine and atrazine.