Application of Mn/MCM-41 as an adsorbent to remove methyl blue from aqueous solution

• Published in: Journal of colloid and interface science 2014-09, Vol.429 (429), p.25-33
• Main Authors: Shao, Yimin, Wang, Xi, Kang, Yuan, Shu, Yuehong, Sun, Qiangqiang, Li, Laisheng
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Aqueous solutions; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Kinetics; Manganese; Mathematical analysis; Methyl blue; Mn/MCM-41; Porosity; Porous materials; Solid-liquid interface; Surface chemistry; Surface physical chemistry; Thermodynamic
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2014.05.004

[Display omitted] •Mn/MCM-41 was prepared and used as a novel adsorbent to remove methyl blue.•Mn modification increased active sites on MCM-41 for removing methyl blue.•Mn/MCM-41 exhibited highly adsorption capacity of methyl blue.•The electrostatic interaction is the main mechanism of adsorption of methyl blue.•Methyl blue adsorption on Mn/MCM-41 was endothermic and spontaneous. In this study, the application of Mn loaded MCM-41 (Mn/MCM-41) was reported as a novel adsorbent for methyl blue (MB) from aqueous solution. The mesoporous structure of Mn/MCM-41 was confirmed by XRD technique. Surface area, pore size and wall thickness were calculated from BET equation and BJH method using nitrogen sorption technique. FT-IR studies showed that Mn were loaded on the hexagonal mesoporous structures of MCM-41. It is found that the MCM-41 structure retained after loading of Mn but its surface area and pore diameter decreased due to pore blockage. Adsorption of MB from aqueous solution was investigated by Mn/MCM-41 with changing Mn content, adsorbent dosage, initial MB concentration, contact time, pH and the temperature. Under the chosen condition (25°C, 0.02g adsorbent dosage, 6.32 pH, 50mgL−1 MB, 1wt.% Mn), a high MB adsorption capacity (45.38mgg−1) was achieved by Mn/MCM-41 process at 120min, 8.6times higher than MCM-41. The electrostatic interaction was considered to be the main mechanism for the dye adsorption. The experimental data fitted well to Freundlich and Dubinin–Radushkevich isotherms. The adsorption of MB on Mn/MCM-41 followed pseudo-second-order kinetics. Thermodynamic parameters suggested that the adsorption process is endothermic and spontaneous.