Preparation and characterization of modified sepiolite for the removal of Acid green 20 from aqueous solutions: isotherm, kinetic and process optimization

Abstract

Abstract In this study, adsorption of Acid green 20 (AG20) by modified sepiolite, hexadecyltrimethylammonium-modified sepiolite (HDTMA-Sep), was optimized using response surface methodology based on a central composite design. Characteristics of natural sepiolite and modified sepiolite can be analyzed by FTIR and XRD techniques. In order to achieve a better comprehension of applicability of adsorbent for removing dyes from colored effluents, isotherm and kinetic studies were also carried out. The maximum dye removal of 78% and 72% for synthetic solutions and real wastewater, respectively, was obtained at the initial dye concentration of 77.1 mg/L, contact time of 24.81 min, solution pH of 6.19 and adsorbent dosage of 1.03 g/L. The kinetic studies revealed that the adsorption process followed pseudo-second-order model. The adsorption data were best fitted to Freundlich model. The result indicated that the contact time and dye concentration have more influence on the removal efficiency rather than pH and amount of adsorbent. The experimental data from this study indicated that the modified sepiolite is an efficient adsorbent for dye removal from aqueous solutions.

Keywords

• Adsorption
• Sepiolite
• Response surface methodology
• Acid green 20
• Central composite design