title: Poly(ethylene imine)-modified graphene oxide with improved colloidal stability and its adsorption of methyl orange.
abstract: Graphene oxide (GO) was chemically modified with poly(ethylene imine) (PEI) to improve its colloidal stability and was investigated as a potential adsorbent for the removal of methyl orange (MO). The synthesis of PEI-GO was verified with a Fourier transform infrared spectrometer and thermogravimetric analysis. A series of adsorption experiments were carried out to investigate the adsorption capacity of PEI-GO. Adsorption kinetics and thermodynamics studies were performed, and the thermodynamic parameters were calculated. The results showed that PEI could improve the colloidal stability of GO in aqueous solution, and the obtained PEI-GO showed a macroscopically homogeneous dispersion after more than three months. After standing for 90 days, the Brunauer-Emmett-Teller specific surface area of GO decreased from 353 to 214 m2·g(-1), while that of PEI-GO remained almost unchanged (from 432 to 413 m2·g(-1)). The PEI-GO exhibited significantly faster kinetic and higher adsorption capacity for MO than GO. Moreover, PEI-GO had a good adsorption capacity in the acidic range, and the highest adsorption of MO occurred at pH=6.0. The adsorption of MO on PEI-GO was an endothermic, spontaneous and physisorption process.
authors.affiliation: Department of Light chemical engineering, Guangdong Polytechnic, Foshan, 528041, China E-mail: angelwu2006@163.com.
authors.forename: Hongxi
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Light chemical engineering, Guangdong Polytechnic, Foshan, 528041, China E-mail: angelwu2006@163.com.
authors.forename: Ting
authors.initials: T
authors.lastname: Wu
authors.affiliation: Department of Light chemical engineering, Guangdong Polytechnic, Foshan, 528041, China E-mail: angelwu2006@163.com.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Guangzhou Panyu Polytechnic, Guangzhou, 511483, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Guangdong Polytechnic, Foshan, 528041, China.
authors.forename: Keqin
authors.initials: K
authors.lastname: Xuan
authors.affiliation: Department of Chemistry, Jinan University, Guangzhou, 510632, China.
authors.forename: Jinglin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Jinan University, Guangzhou, 510632, China.
authors.forename: Shaozao
authors.initials: S
authors.lastname: Tan
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000302:isolation & purification*; D003102:Colloids; D006108:Graphite / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D007700:Kinetics; D010087:Oxides / Q000737:chemistry*; D011095:Polyethylenes / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D001391:Azo Compounds; D003102:Colloids; D007097:Imines; D010087:Oxides; D011095:Polyethylenes; D014874:Water Pollutants, Chemical; C505405:poly(ethylene imine); C100258:methyl orange; D006108:Graphite