title: Uptake of Pb(II) and Cd(II) on Chitosan Microsphere Surface Successively Grafted by Methyl Acrylate and Diethylenetriamine.
abstract: A novel adsorbent, CS-MA-DETA microspheres, for uptake of heavy metal ions from aqueous solutions was first fabricated via two-step grafting methyl acrylate (MA) and diethylenetriamine (DETA) onto chitosan (CS) microsphere surface in the absence of cross-linkers. CS-MA-DETA microspheres of 3.04 μm in mean diameter were of uniformly wrinkle-like topography sketched out by SEM, whose surface after decoration by MA and DETA was stable and beneficial to metal ion capture. Its chemical composition, microstructure, and thermal property were characterized by elemental analysis, FTIR, XRD, BET, and TGA techniques, and the achieved quantitative results mainly included C/N ratio (4.76), crystallinity (31.20%, 19.75% of CS), specific surface area (27.806 m2g-1), pore diameter (3.452 nm), and mass loss at the first stage (3%, around 10% of CS), which indicated a successful synthesis, well-defined structure, and good thermostability. Adsorption tests of CS-MA-DETA microspheres were performed in Pb(II) and/or Cd(II) solution(s) at various pH values, contact time, and initial concentrations, exhibiting an excellent adsorption capability. Its maximum adsorption capacity calculated by Langmuir model was 239.2 mg Pb(II)/g, or 201.6 mg Cd(II)/g, which was higher than those of most available CS-based adsorbents. Furthermore, several adsorption kinetic and isotherm models were employed to investigate its uptake behavior, implying that it was mainly a monolayer adsorption and chemisorption process. Five-cycle reusability tests demonstrated CS-MA-DETA microspheres could be repeatedly used without significant capacity loss (<10%). Additionally, several potential bonding modes and adsorption sites for both metal ions were also proposed. Overall, CS-MA-DETA microspheres with outstanding adsorption performance toward Pb(II) and/or Cd(II) might serve as a new absorbent for wastewater purification.
authors.affiliation: College of Marine Life Sciences, Ocean University of China , 5 Yushan Road, Qingdao 266003, P.R. China.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Zhang
authors.affiliation: College of Marine Life Sciences, Ocean University of China , 5 Yushan Road, Qingdao 266003, P.R. China.
authors.forename: Qifeng
authors.initials: Q
authors.lastname: Dang
authors.affiliation: College of Marine Life Sciences, Ocean University of China , 5 Yushan Road, Qingdao 266003, P.R. China.
authors.forename: Chengsheng
authors.identifier: http://orcid.org/0000-0002-1454-0193
authors.initials: C
authors.lastname: Liu
authors.affiliation: The Graduate School of Biotechnology, Korea University , Seoul 136-701, South Korea.
authors.forename: Dongsu
authors.initials: D
authors.lastname: Cha
authors.affiliation: College of Marine Life Sciences, Ocean University of China , 5 Yushan Road, Qingdao 266003, P.R. China.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Yu
authors.affiliation: College of Marine Life Sciences, Ocean University of China , 5 Yushan Road, Qingdao 266003, P.R. China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Qingdao Aorun Biotechnology Co., Ltd., Room 602, Century Mansion, 39 Donghaixi Road, Qingdao 266071, P.R. China.
authors.forename: Bing
authors.initials: B
authors.lastname: Fan
keywords: Cd(II); Pb(II); chitosan-based microsphere; diethylenetriamine; high adsorption capacity; methyl acrylate