title: SBA-15-incorporated nanoscale zero-valent iron particles for chromium(VI) removal from groundwater: mechanism, effect of pH, humic acid and sustained reactivity.
abstract: Nanoscale zero-valent iron particles (NZVIs) were incorporated inside the channels of SBA-15 rods by a "two solvents" reduction technique and used to remove Cr(VI) from groundwater. The resulting NZVIs/SBA-15 composites before and after reaction were characterized by N2 adsorption/desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Results helped to propose the mechanism of Cr(VI) removal by NZVIs/SBA-15, where Cr(VI) in aqueous was firstly impregnated into the channels of the silica, then adsorbed on the surfaces of the incorporated NZVIs and reduced to Cr(III) directly in the inner pores of the silica. Corrosion products included Fe2O3, FeO(OH), Fe3O4 and Cr2FeO4. Batch experiments revealed that Cr(VI) removal decreased from 99.7% to 92.8% when the initial solution pH increased from 5.5 to 9.0, accompanied by the decrease of the kobs from 0.600 to 0.024 min(-1). Humic acid (HA) had a little effect on the removal efficiency of Cr(VI) by NZVIs/SBA-15 but could decrease the reduction rate. The stable reduction of NZVIs/SBA-15 was observed within six cycles. NZVIs/SBA-15 composites offer a promising alternative material to remove heavy metals from groundwater.
authors.affiliation: School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China; School of Chemistry and Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005, PR China. Electronic address: lygsunxia@163.com.
authors.forename: Xia
authors.initials: X
authors.lastname: Sun
authors.affiliation: School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China.
authors.forename: Yubo
authors.initials: Y
authors.lastname: Yan
authors.affiliation: School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China. Electronic address: lijsh@mail.njust.edu.cn.
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China.
authors.forename: Weiqing
authors.initials: W
authors.lastname: Han
authors.affiliation: School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China. Electronic address: wanglj@mail.njust.edu.cn.
authors.forename: Lianjun
authors.initials: L
authors.lastname: Wang
mesh_terms: D002857:Chromium / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods; D060587:Groundwater; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D006812:Humic Substances; C509969:SBA-15; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D012822:Silicon Dioxide; D007501:Iron
keywords: Chromium(VI); Humic acid; Mechanism; Two solvents technique; Zero-valent iron