Adsorption of methylene blue by a high-efficiency adsorbent (polydopamine microspheres): Kinetics, isotherm, thermodynamics and mechanism analysis

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 259; pp. 53 - 61
• Main Authors: Fu, Jianwei, Chen, Zhonghui, Wang, Minghuan, Liu, Shujun, Zhang, Jinghui, Zhang, Jianan, Han, Runping, Xu, Qun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2015
• Subjects: Adsorption; Isotherms; Kinetics; Methylene blue; Thermodynamic; Waste water; Kinetics; Adsorption; Isotherms; Waste water; Methylene blue; Thermodynamic
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2014.07.101

[Display omitted] •We reported a novel polymer adsorbent which can be facilely synthesized.•The adsorbent was an efficient and specific adsorbent for the removal of MB.•The equilibrium adsorption data fitted the Langmuir isotherm well.•The pseudo-second-order model could be better to describe the adsorption of MB.•The adsorption of MB onto the polymer adsorbent was endothermic and spontaneous. Polydopamine (PDA) microspheres were synthesized by a facile oxidative polymerization method and used as a high-efficiency adsorbent for the removal of a cationic dye (methylene blue, MB) from aqueous solution. Characterizations of the as-synthesized PDA microspheres and PDA microspheres-MB (MB absorbed PDA microspheres) systems were performed using several techniques such as SEM, TEM, FTIR, N2 adsorption/desorption isotherms, particle size and zeta potential analysis. The effects of initial solution pH, temperature, initial concentration, and contact time were systematically investigated. Results showed the adsorption capacity at 25°C could reach up to 90.7mg/g. Besides, adsorption kinetics showed that the adsorption behavior followed the pseudo-second-order kinetic model. The equilibrium adsorption data fitted the Langmuir isotherm well. Thermodynamic analyses showed that the adsorption was endothermic and spontaneous, and it was also a physisorption process. In addition, the possible adsorption mechanism was also proposed based on the experimental results.