title: Preparation and characterization of magnetic Fe3O 4/CNT nanoparticles by RPO method to enhance the efficient removal of Cr(VI).
abstract: This work described a novel method for the synthesis of high-ferromagnetism nanoparticles (Fe3O4/CNTs) to efficiently remove Cr(VI) from aqueous solution. The Fe3O4/carbon nanotubes (CNTs) were prepared by in situ reduction with post-oxidation method by using cheap and environmentally friendly precursor under mild condition. Magnetic hysteresis loops revealed that Fe3O4/CNTs had superior saturation magnetization (152 emu/g), enabling the highly efficient recovery of Fe3O4/CNTs from aqueous solution by magnetic separation at low magnetic field gradients. FTIR, Raman, XPS, and TEM observations were employed to characterize the physical-chemical properties of Fe3O4/CNTs, demonstrating that CNTs were successfully coated with iron oxide matrix. The adsorption equilibrium of Cr(VI) on Fe3O4/CNTs was reached within 30 min. Langmuir, Freundlich, and Dubinin-Radushkevich isotherm were chosen to analyze the equilibrium data. The results indicated that Langmuir model can well describe the equilibrium data with the maximum adsorption capacity of 47.98 mg/g at room temperature and 83.54 mg/g at 353 K. The adsorption capacity of Fe3O4/CNTs for Cr(VI) was greatly improved as compared to raw CNTs and other similar adsorbents reported. The pseudo-second-order kinetic model provided the best description of Cr(VI) adsorption on Fe3O4/CNTs. Most importantly, possible synthesis mechanism and Cr(VI) removal mechanism were explored. The results suggest that large amounts of Cr(VI) were adsorbed on Fe3O4/CNTs surface by substituting the surface position of -OH and then reducing it to Cr(OH)3 and Cr2O3.
authors: School of Metallurgical Science and Engineering, Central South University, Changsha, 410083, China.
authors: Runhua
authors: R
authors: Chen
authors: Liyuan
authors: L
authors: Chai
authors: Qinzhu
authors: Q
authors: Li
authors: Yan
authors: Y
authors: Shi
authors: Yangyang
authors: Y
authors: Wang
authors: Ali
authors: A
authors: Mohammad
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000032:analysis / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D007700:Kinetics; D008280:Magnetics; D008956:Models, Chemical; D037742:Nanotubes, Carbon / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D005290:Ferric Compounds; D037742:Nanotubes, Carbon; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; C000499:ferric oxide
references: Environ Sci Technol. 1996 May 23;30(6):248A-51A
references: 21648723
references: J Hazard Mater. 2010 Mar 15;175(1-3):816-22
references: 19926221
references: J Hazard Mater. 2012 Oct 15;235-236:246-56
references: 22902142
references: Environ Sci Pollut Res Int. 2012 Jun;19(5):1687-95
references: 22161297
references: J Hazard Mater. 2008 Jun 30;155(1-2):65-75
references: 18162297
references: Nano Lett. 2005 May;5(5):879-84
references: 15884887
references: J Hazard Mater. 2010 Oct 15;182(1-3):295-302
references: 20621418
references: Int J Biol Macromol. 2011 Nov 1;49(4):513-22
references: 21684304
references: J Hazard Mater. 2012 Mar 30;209-210:193-8
references: 22321856
references: Environ Sci Technol. 2012 Nov 20;46(22):12542-9
references: 23092182
references: Environ Sci Pollut Res Int. 2012 Jun;19(5):1800-8
references: 22203400
references: Water Res. 2011 Mar;45(6):2207-12
references: 21303713
references: Environ Sci Pollut Res Int. 2011 Jul;18(6):857-64
references: 21249458
references: Environ Sci Pollut Res Int. 2013 Jul;20(7):4647-58
references: 23288677
references: J Phys Chem B. 2006 Apr 13;110(14):7213-20
references: 16599489
references: Environ Sci Pollut Res Int. 2011 Aug;19(7):2983-93
references: 22374187
references: Anal Chim Acta. 2012 Apr 29;724:54-60
references: 22483209
references: J Hazard Mater. 2007 Apr 2;142(1-2):191-8
references: 16978771
references: J Hazard Mater. 2004 Aug 30;112(3):225-31
references: 15302443
references: J Hazard Mater. 2009 Jul 15;166(1):270-6
references: 19117674