Adsorption behaviors of the methylene blue dye onto modified sepiolite from its aqueous solutions

摘要

The natural sepiolite was modified by nitric acid followed by a heat treatment, and then used as adsorbent for the removal of methylene blue (MB) dye from aqueous solution. The adsorbents were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Batch adsorption experiments were carried out to study the effect of various parameters, such as the initial MB concentration, adsorbent dosage, contact time, pH value, and temperature on the adsorption of MB dye. The isotherm analysis indicated that the adsorption data can be represented by the Langmuir isotherm model; the maximum adsorption capacity was up to 90.211mg/g. Kinetic studies showed that the adsorption data followed the pseudo-second-order model. Thermodynamic studies suggested that the adsorption of MB dye on modified sepiolite was a spontaneous and exothermic process. The results indicate that the modified sepiolite has excellent physical and chemical properties and can serve as a promising adsorbent for the removal of MB dyes from aqueous solutions.