Abstract

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Zeolite synthesized from coal bottom ash (ZBA) was modified with hexadecyltrimethylammonium bromide and was examined for the adsorption of Acid Orange 8 (AO8) from water. The ZBA and surfactant-modified ZBA (SMZBA) were characterized to obtain chemical and mineralogical composition, total and external cation-exchange capacity among other parameters. Results indicate that, while ZBA had no affinity for AO8, SMZBA showed greatly enhanced adsorption capacity. The dye adsorption equilibrium was rapidly attained after 90 min of contact time. The adsorption kinetic was discussed using the pseudo-first order and pseudo-second order. The experimental equilibrium data were tested by four widely used isotherm models namely, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich. It was found that adsorption of AO8 on SMZBA well with the Langmuir isotherm model. The monolayer adsorption capacity was 1.15 mg g-1 with the correlation coefficient of 0.99. The negative value of the free energy change indicates the spontaneous nature of the adsorption. The experimental results suggest that SMZBA could be employed as an adsorbent in the removal of AO8 dye from aqueous solution and wastewater.

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