Adsorption of Telon dyes onto bis-imidazolium modified bentonite in aqueous solutions

• Bentonites could be employed as low-cost material for adsorption of Telon dyes.
• Interlayer spacing and hydrophobicity of bentonite influence on adsorption capacity.
• Geometry and volume of organic molecules influence on d0 0 1 of organo-Bt.
• Adsorption capacity of Telon dyes is inversely proportional to size of dye molecules.

Clay ion-exchange using bis-imidazolium salts (MBIM) could provide organophilic clays materials that allow effective retention of polluting dyes. The present investigations deal with bentonite (Bt) modification using (ortho, meta and para) bis-imidazolium cations and attempts to remove a synthetic textile dyes, such as Telon-Orange, Telon-Red and Telon-Blue by adsorption, from aqueous solutions. The surface modification of MBIM–Bt was examined using infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Adsorption tests applied to Telon dyes revealed a significant increase of the maximum adsorption capacity from ca. 21–28–88–108 mg/g after intercalation. The highest adsorption level was noticed for Telon-Orange dye on the p-MBIM–Bt, presumably due higher interlayer space and better diffusion. The pseudo-first order rate equation was able to provide the best description of adsorption kinetics data for all three dyestuffs. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms, and the isotherm constants were also determined. The results show that MBIM–Bt could be employed as low-cost material for the removal of Telon dyes from effluents.

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