title: Adsorptive removal of methylene blue by rhamnolipid-functionalized graphene oxide from wastewater.
abstract: In this article, a rhamnolipid-functionalized graphene oxide (RL-GO) hybrid was prepared by one-step ultrasonication and adsorptive removal of methylene blue (MB) from both artificial and real wastewater by the RL-GO was investigated. The Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) area and Zeta potential analysis were used to characterize the adsorbent. The results showed that RL-GO had abundant functional groups and a mesopores feature. MB adsorption by the RL-GO increased with increase in adsorbent dose, pH, temperature and initial MB concentration, while it was insensitive to ionic strength variation. The adsorption kinetics fitted well to the pseudo-second-order model with correlation coefficients greater than 0.999. The Intra-particle diffusion and Boyd's film-diffusion models showed that the rate-controlled step was dominated by film-diffusion in the beginning and then followed by intra-particle diffusion. The adsorption isotherm was fitted by adsorption models with the suitability in order of BET > Freundlich > Langmuir > Temkin, based on comparison between correlation coefficients. Thermodynamic analysis of equilibriums suggested that the adsorption MB on RL-GO was spontaneous and endothermic. The adsorption mechanism was also proposed to be electrostatic attraction, π-π interaction and hydrogen bond. In addition, the real wastewater experiment, the regeneration study and the comparative cost analysis showed that the RL-GO composites could be a cost-effective and promising sorbent for MB wastewater treatment owing to its high efficiency and excellent reusability.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Wu
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China; Department of Soil, Water and Environmental Science, The University of Arizona, Tucson AZ85719, USA. Electronic address: zhonghua@hnu.edu.cn.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhong
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China. Electronic address: yxz@hnu.edu.cn.
authors.forename: Xingzhong
authors.initials: X
authors.lastname: Yuan
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
authors.forename: Hou
authors.initials: H
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
authors.forename: Lele
authors.initials: L
authors.lastname: Wang
authors.affiliation: School of Business, Central South University, Changsha 410083, PR China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Chen
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zeng
authors.affiliation: College of Environment and Energy, South China University of Technology Guangzhou 510006, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000327:Adsorption; D006017:Glycolipids; D006108:Graphite / Q000737:chemistry*; D007700:Kinetics; D008751:Methylene Blue / Q000302:isolation & purification*; D008956:Models, Chemical; D014465:Ultrasonics / Q000379:methods; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D006017:Glycolipids; D006108:Graphite; D008751:Methylene Blue; D062065:Wastewater; D014874:Water Pollutants, Chemical; C418382:rhamnolipid
keywords: Adsorption; Adsorption isotherms; Adsorption kinetics; Methylene blue; Rhamnolipid-functionalized graphene oxide