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Modified fly ash and zeolites as an effective adsorbent for metal ions from aqueous solution

Zeolite Na–X and chitosan-modified Na–X–CS were used as adsorbents for the removal of Cu(II), Fe(III), Mn(II) and Zn(II) from aqueous solutions. They were prepared based on fly ash by hydrothermal reaction using the NaOH solution under controlled conditions. Characterization of the Na–X and Na–X–CS sorbents was made using Fourier transform infrared spectroscopy with the attenuated total reflection mode, X-ray fluorescence and X-ray diffraction, nitrogen adsorption and desorption, acidity measurements and scanning electron microscopy techniques. The effects of adsorption time, the amount of sorbent and the concentration of metal ions on the removal percentage and sorption capacities were studied. The sorption percentage increased with the increasing phase contact time and zeolite amount. The adsorption mechanism was also discussed. The results revealed that Na–X–CS adsorbs Cu(II), Fe(III), Mn(II) and Zn(II) ions more effectively than zeolite Na–X and proved that modification by CS leads to an increase in the adsorption efficiency of the zeolites.