title: Adsorption of copper(II) ions by a chitosan-oxalate complex biosorbent.
abstract: Oxalic acid, an effective metal-chelating ligand, is abundant in natural resources. In this study, a chitosan-oxalate complex biosorbent (COCB) was prepared by an iontropic cross-linking method. The COCB beads were characterized by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The XRD analysis shows that Cu(II) ions can form complexes with chitosan and oxalate. Adsorption of Cu(II) ions onto COCB beads was pH-dependent. The isothermal adsorption data fitted well to Langmuir equation with the maximum adsorption capacities of 227.27 mg/g for porous COCB beads and 175.44 mg/g for non-porous COCB beads at pH 5.0. The adsorption kinetics described by the pseudo-second-order diffusion models, suggesting that the rate-limiting step in adsorption was chemical sorption. Thermodynamic parameters (ΔG°<0 and ΔH°>0) indicated a spontaneous and endothermic adsorption process. The COCB bioadsorbent exhibited fast adsorption rate and high adsorption capacity for Cu(II) uptake.
authors.affiliation: Department of Biochemistry and Molecular Cell Biology, School of Medicine, Taipei Medical University, Taipei 110, Taiwan; Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 110, Taiwan.
authors.forename: Fwu-Long
authors.initials: FL
authors.lastname: Mi
authors.affiliation: Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan. Electronic address: sjwu@mail.mcut.edu.tw.
authors.forename: Shao-Jung
authors.initials: SJ
authors.lastname: Wu
authors.affiliation: Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan.
authors.forename: Fu-Ming
authors.initials: FM
authors.lastname: Lin
mesh_terms: D000327:Adsorption; D048271:Chitosan / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008863:Microspheres; D010070:Oxalates / Q000737:chemistry*; D016062:Porosity; D012996:Solutions; D013696:Temperature; D013818:Thermogravimetry; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D007477:Ions; D010070:Oxalates; D012996:Solutions; D003300:Copper; D048271:Chitosan
keywords: Biosorbent; Chitosan; Oxalic acid