Synthesis of chromium pillared clay for adsorption of methylene blue

Synthesis of chromium pillared clay and its application for methylene blue adsorption has been conducted. Chromium pillared clays were prepared through intercalation of chromium polycation in the area between clay silicate layers. Whereas chromium polycation was synthesized by hydrolysis of CrCl₃.6H₂O solution with NaOH. The intercalated clay then dried and calcined at 200°C for 4 hours. The resulting chromium pillar clay was characterized by X-Ray Diffraction (XRD) and Surface Area Analyser (SAA). Furthermore, natural clays and chromium pillared clay were used as adsorbents for methylene blue adsorption. Chromium pillared clays showed better characteristics than natural clays. Basal spacing increased from 15.08 Å to 16.28 Å, surface area from 41.636 m²/g to 130.555 m²/g, average pore diameter from 30.516 Å to 30.590 Å, and pore volume from 0.067 mL/g to 0.128 mL/g. The adsorption results displayed that the optimum adsorption conditions occurred at pH 2 and there was no significant difference in adsorption ability due to time variation. The optimum efficiency for methylene blue adsorption was at a concentration of 180 ppm for natural clay and of 120 ppm for chromium pillared clay.