title: Application of bifunctional magnetic adsorbent to adsorb metal cations and anionic dyes in aqueous solution.
abstract: A magnetic adsorbent, amine-functionalized silica magnetite (NH(2)/SiO(2)/Fe(3)O(4)), has been synthesized to behave as an anionic or cationic adsorbent by adjusting the pH value of the aqueous solution to make amino groups protonic or neutral. NH(2)/SiO(2)/Fe(3)O(4) were used to adsorb copper ions (metal cation) and Reactive Black 5 (RB5, anionic dye) in an aqueous solution in a batch system, and the maximum adsorption were found to occur at pH 5.5 and 3.0, respectively. The adsorption equilibrium data were all fitted the Langmuir isotherm equation reasonably well, with a maximum adsorption capacity of 10.41 mg g(-1) for copper ions and of 217 m g g(-1) for RB5. A pseudo-second-order model also could best describe the adsorption kinetics, and the derived activation energy for copper ions and RB5 were 26.92 kJ mol(-1) and 12.06 kJ mol(-1), respectively. The optimum conditions to desorb cationic and anionic adsorbates from NH(2)/SiO(2)/Fe(3)O(4) were provided by a solution with 0.1M HNO(3) for copper ions and with 0.05 M NaOH for RB5.
authors.affiliation: Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 260, Taiwan.
authors.forename: Ya-Fen
authors.initials: YF
authors.lastname: Lin
authors.forename: Hua-Wei
authors.initials: HW
authors.lastname: Chen
authors.forename: Poh-Sun
authors.initials: PS
authors.lastname: Chien
authors.forename: Chyow-San
authors.initials: CS
authors.lastname: Chiou
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Liu
mesh_terms: D000327:Adsorption; D000838:Anions / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D007700:Kinetics; D008280:Magnetics; D008670:Metals / Q000737:chemistry*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D000838:Anions; D002412:Cations; D008670:Metals; D012996:Solutions; D014867:Water