title: Adsorption of C.I. Reactive Red 228 and Congo Red dye from aqueous solution by amino-functionalized Fe3O4 particles: kinetics, equilibrium, and thermodynamics.
abstract: A magnetic adsorbent was synthesized by γ-aminopropyltriethoxysilane (APTES) modification of Fe(3)O(4) particles using a two-step process. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vibration sample magnetometry were used to characterize the obtained magnetic adsorbent. EDS and XPS showed that APTES polymer was successfully introduced onto the as-prepared Fe(3)O(4)/APTES particle surfaces. The saturation magnetization of the magnetic adsorbent was around 65 emu g(-1), which indicated that the dye can be removed fast and efficiently from aqueous solution with an external magnetic field. The maximum adsorption capacities of Fe(3)O(4)/APTES for C.I. Reactive Red 228 (RR 228) and Congo Red (CR) were 51.4 and 118.8 mg g(-1), respectively. The adsorption of C.I. Reactive Red 228 (RR 228) and Congo Red (CR) on Fe(3)O(4)/APTES particles corresponded well to the Langmuir model and the Freundlich model, respectively. The adsorption processes for RR 228 and CR followed the pseudo-second-order model. The Boyd's film-diffusion model showed that film diffusion also played a major role in the studied adsorption processes for both dyes. Thermodynamic study indicated that both of the adsorption processes of the two dyes are spontaneous exothermic.
authors.affiliation: Key Laboratory of Bio-based Material Science and Technology of Ministry of Education, Northeast Forestry University, 26 Hexing Road, Harbin 150040, China E-mail: donglinwlj@163.com.
authors.forename: Ting-guo
authors.initials: TG
authors.lastname: Yan
authors.affiliation: Key Laboratory of Bio-based Material Science and Technology of Ministry of Education, Northeast Forestry University, 26 Hexing Road, Harbin 150040, China E-mail: donglinwlj@163.com.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D000817:Anilino Naphthalenesulfonates / Q000302:isolation & purification*; D001713:Biphenyl Compounds / Q000302:isolation & purification*; D004396:Coloring Agents / Q000302:isolation & purification*; D003224:Congo Red / Q000302:isolation & purification*; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011437:Propylamines; D012821:Silanes / Q000737:chemistry*; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D000817:Anilino Naphthalenesulfonates; D001713:Biphenyl Compounds; C587837:C.I. Reactive Red 228; D004396:Coloring Agents; D011437:Propylamines; D012821:Silanes; D014874:Water Pollutants, Chemical; D003224:Congo Red; C477625:amino-propyl-triethoxysilane; D052203:Ferrosoferric Oxide