title: Highly Porous Core-Shell Structured Graphene-Chitosan Beads.
abstract: Graphene oxide (GO) sheets have been assembled into various three-dimensional porous structures and composites, with potential applications in energy and environmental areas. Here, we show the combination of GO and chitosan (CTS) into inorganic-organic heterocomposites as ∼3 mm diameter core-shell beads with controlled microstructure. The spherical GO-CTS beads, made by a two-step freeze-casting method, consist of a GO core wrapped by a CTS shell with abrupt interface; both parts have high porosities (94-96%) and mesopores volume (0.246 cm(3)/g) yet with different pore morphologies. Incorporation of a GO core into the CTS beads significantly improved the methyl orange adsorption capacity (353 mg/g at 318 K) compared with pure CTS beads. Key factors such as the pH value, adsorbent dosage, concentration, time, and temperature have been studied in detail, whereas adsorption isotherm and kinetic studies reveal a Langmuir model following the pseudo-second order.
authors.affiliation: †Department of Mechanical Engineering, Tsinghua University, Beijing 100084, P. R. China.
authors.forename: An
authors.initials: A
authors.lastname: Ouyang
authors.affiliation: ‡Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080, P.R. China.
authors.forename: Chunhui
authors.initials: C
authors.lastname: Wang
authors.affiliation: §Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, P. R. China.
authors.forename: Shiting
authors.initials: S
authors.lastname: Wu
authors.affiliation: §Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, P. R. China.
authors.forename: Enzheng
authors.initials: E
authors.lastname: Shi
authors.affiliation: ‡Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080, P.R. China.
authors.forename: Wenqi
authors.initials: W
authors.lastname: Zhao
authors.affiliation: §Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, P. R. China.
authors.forename: Anyuan
authors.initials: A
authors.lastname: Cao
authors.affiliation: †Department of Mechanical Engineering, Tsinghua University, Beijing 100084, P. R. China.
authors.forename: Dehai
authors.initials: D
authors.lastname: Wu
keywords: chitosan; core−shell beads; freeze-casting; graphene; methyl orange adsorption