Removal of remazol yellow from aqueous solutions by unmodified and stabilized iron modified clay

The adsorption behavior of remazol yellow from aqueous solutions onto montmorillonite KSF and iron modified montmorillonite KSF samples was investigated as a function of initial concentration of remazol yellow, contact time and pH. The regeneration of the dye saturated material was also considered.The sorption showed that the montmorillonite KSF removed about 10% more dye than the iron modified montmorillonite KSF but the standard deviations of the experiments were very high for the unmodified material. The kinetic experiments showed that the equilibrium time was reached in less than an hour for both materials and the experimental data were adjusted to the pseudo first order model (Lagergren), which is based on a surface reaction.The experimental data could be adjusted to the Langmuir, Freundlich and Langmuir–Freundlich models, but according to the characteristics of the adsorbents only the two last models should be considered because the adsorbents are heterogeneous. It was also observed that the sorption capacities for the iron modified montmorillonite were not affected by pH from 2 to 12.The results on the desorption processes showed that the best regenerator agent was Fenton's reagent, the sorption capacities were a little higher for iron modified montmorillonite KSF than for montmorillonite KSF in the first 7 sorption–desorption cycles and then the sorption of the dye increases almost 3 times in the 8–10 sorption–desorption cycles.