title: Adsorption of methylene blue onto poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) nanotubes: kinetics, isotherm and thermodynamics analysis.
abstract: Poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) nanotubes, an excellent adsorbent, were successfully synthesized by an in situ template method and used for the removal of methylene blue (MB) from aqueous solution. The morphology and structures of as-synthesized PZS nanotubes were characterized by scanning electron microscopy, transmission electron microscope, Fourier transform infrared spectroscopy and N2 adsorption/desorption isotherms. The effects of temperature, concentration, pH and contact time on MB adsorption were studied. It was favorable for adsorption under the condition of basic and high temperature. The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to fit adsorption data in the kinetic studies. And results showed that the adsorption kinetics were more accurately described by the pseudo-second-order model. The equilibrium isotherms were conducted using Freundlich and Langmuir models. It has been demonstrated that the better agreement was Langmuir isotherm with correlation coefficient of 0.9933, equilibrium absorption capacity of 69.16mg/g and the corresponding contact time of 15min. Thermodynamic analyses showed that MB adsorption onto the PZS nanotubes was endothermic and spontaneous and it was also a physisorption process.
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University, 75 Daxue Road, Zhengzhou 450052, PR China.
authors.forename: Zhonghui
authors.initials: Z
authors.lastname: Chen
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University, 75 Daxue Road, Zhengzhou 450052, PR China.
authors.forename: Jianan
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University, 75 Daxue Road, Zhengzhou 450052, PR China. Electronic address: jwfu@zzu.edu.cn.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Fu
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University, 75 Daxue Road, Zhengzhou 450052, PR China.
authors.forename: Minghuan
authors.initials: M
authors.lastname: Wang
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University, 75 Daxue Road, Zhengzhou 450052, PR China.
authors.forename: Xuzhe
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450052, PR China.
authors.forename: Runping
authors.initials: R
authors.lastname: Han
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University, 75 Daxue Road, Zhengzhou 450052, PR China. Electronic address: qunxu@zzu.edu.cn.
authors.forename: Qun
authors.initials: Q
authors.lastname: Xu
mesh_terms: D000327:Adsorption; D004396:Coloring Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008751:Methylene Blue / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D009943:Organophosphorus Compounds / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013816:Thermodynamics; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D009943:Organophosphorus Compounds; D010636:Phenols; D014874:Water Pollutants, Chemical; C586567:poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol); D008751:Methylene Blue
keywords: Equilibrium isotherm; Kinetic model; Methylene blue; Nanotubes; Thermodynamic