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Accumulation of waste represents one of the biggest problems of modern civilization, from the energy, construction, urban, ecological and technological point of view. In this work, fly ash, as waste material from the power plant Nikola Tesla, was activated with sodium hydroxide at elevated temperature and then chemically modified with different amounts of polyethylenimine (PEI). The successfulness of modification was confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. Prepared materials were then used to remove cadmium from wastewater and an increase in adsorption efficiency was observed for the fly ash sample modified with a smaller amount of PEI, with respect to the unmodified sample. The results of the adsorption experiments were processed using Langmuir and Freundlich adsorption isotherms and pseudo-first and pseudo-second order kinetic models. Also, the possibility of reusing the material in several cycles was examined. It was found that fly ash, modified with an optimal amount of polyethyleneimine, could be an effective adsorbent.
Fig. 1. FTIR spectra (a) and adsorption efficiency (b) of unmodified and modified fly ash
Keywords: fly ash, polyethylenimine, modification, adsorption, heavy metals
Acknowledgment. This work was supported by the Science Fund of the Republic of Serbia within project „Serbian Industrial Waste towards Sustainable Environment: Resource of Strategic Elements and Removal Agent for Pollutants - SIW4SE“ (Contracts No. 7743343).
