Magnetite nanoparticles activated coal fly ash zeolites with application in waste water remediation

The application of zeolites in wastewater treatment is studied long ago but still many unexploited opportunities exist. Recent investigations on natural and synthetic zeolites in water decontamination are focused on the improvement of their adsorption and ion-exchange properties modifying them by functionalization, acidic treatment or by incorporation of metal nanoparticles. Another target is to obtain magnetic zeolites to facilitate their powders separation from decontaminated media. In the context of environmental protection and conservation of natural resources, zeolites are derived from waste aluminosilicates including also coal fly ash (FA). Fly ash zeolites (FAZ) with excellent surface characteristics are synthesized by double stage fusion-hydrothermal activation including high thermal stage prior to the hydrothermal. Drawback of this synthesis manner is that magnetite from FA undergoes thermal oxidation to hematite preventing the simultaneous presence of Fe2+/3+ ions into FAZ, which is otherwise important for their decontamination efficiency. Thus prepared FAZ also suffer from the disruption of their magnetic activity, as the magnetic zeolites adsorbents are removed from decontaminated media by a simple magnetic process. In this study, FAZ are loaded by magnetite nanoparticles between the two synthesis stages. The obtained nanocomposites and their parent FAZ are tested for decontamination of polluted waters. Acknowledgements This work was financially supported by National Science Funds, Ministries of Education and Science of Republic Bulgaria and Slovak Republic in the frame of bilateral research project under Grant DNTS Slovak Republic 01/6 (SK-BG-2013-0025).