title: Adsorption of tetracycline from aqueous solutions onto multi-walled carbon nanotubes with different oxygen contents.
abstract: Oxidized multi-walled carbon nanotubes (MWCNTs) with different oxygen contents were investigated for the adsorption of tetracycline (TC) from aqueous solutions. As the surface oxygen content of the MWCNTs increased, the maximum adsorption capacity and adsorption coefficient of TC increased to the largest values and then decreased. The relation can be attributed to the interplay between the nanotubes' dispersibility and the water cluster formation upon TC adsorption. The overall adsorption kinetics of TC onto CNTs-3.2%O might be dependent on both intra-particle diffusion and boundary layer diffusion. The maximum adsorption capacity of TC on CNTs-3.2%O was achieved in the pH range of 3.3-8.0 due to formation of water clusters or H-bonds. Furthermore, the presence of Cu(2+) could significantly enhanced TC adsorption at pH of 5.0. However, the solution ionic strength did not exhibit remarkable effect on TC adsorption. In addition, when pH is beyond the range (3.3-8.0), the electrostatic interactions caused the decrease of TC adsorption capacity. Our results indicate that surface properties and aqueous solution chemistry play important roles in TC adsorption on MWCNTs.
authors.affiliation: 1] School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Hai Quan Road, Shanghai 201418, China [2] State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China [3].
authors.forename: Fei
authors.initials: F
authors.lastname: Yu
authors.affiliation: 1] State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China [2].
authors.forename: Jie
authors.initials: J
authors.lastname: Ma
authors.affiliation: School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Hai Quan Road, Shanghai 201418, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Han