title: Synthesis of zeolite-supported microscale zero-valent iron for the removal of Cr(6+) and Cd(2+) from aqueous solution.
abstract: Zeolite-supported microscale zero-valent iron (Z-mZVI) was synthesized and used to remove heavy metal cation (Cd(2+)) and anion (Cr(6+)) from aqueous solution. Transmission electron microscope (TEM) confirmed that mZVI (100-200 nm) has been successfully loaded and efficiently dispersed on zeolite. Atomic absorption Spectroscopy (AAS) revealed the amount of stabilized mZVI was about 1.3 wt.%. The synthesized Z-mZVI has much higher reduction ability and adsorption capacity for Cr(6+) and Cd(2+) compared to bare nanoscale zero-valent iron (nZVI) and zeolite. Above 77% Cr(6+) and 99% Cd(2+) were removed by Z-mZVI, while only 45% Cr(6+) and 9% Cd(2+) were removed by the same amount iron of nZVI, and 1% Cr(6+) and 39% Cd(2+) were removed by zeolite alone with an initial concentration of 20 mg/L Cr(6+) and 200 mg/L Cd(2+). The removal of Cr(6+) by Z-mZVI follows the pseudo first-order kinetics model, and X-ray photoelectron spectroscopy (XPS) analysis confirmed that Cr(6+) was reduced to Cr(3+) and immobilized on the surface of Z-mZVI. The removal mechanisms for Cr(6+) include reduction, adsorption of Cr(3+) hydroxides and/or mixed Fe(3+)/Cr(3+) (oxy)hydroxides. The pseudo-second-order kinetic model indicated that chemical sorption might be rate-limiting in the sorption of Cd(2+) by Z-mZVI. This synthesized Z-mZVI has shown the potential as an efficient and promising reactive material for removing various heavy metals from wastewater or polluted groundwater.
authors.affiliation: Institute of Hydrogeology & Environmental Geology, CAGS, Shijiazhuang, 050061, China; Key Laboratory of Groundwater Contamination Remediation, Shijiazhuang, 050061, China.
authors.forename: Xiangke
authors.initials: X
authors.lastname: Kong
authors.affiliation: Institute of Hydrogeology & Environmental Geology, CAGS, Shijiazhuang, 050061, China; Key Laboratory of Groundwater Contamination Remediation, Shijiazhuang, 050061, China. Electronic address: hanzhantao1977@163.com.
authors.forename: Zhantao
authors.initials: Z
authors.lastname: Han
authors.affiliation: Institute of Hydrogeology & Environmental Geology, CAGS, Shijiazhuang, 050061, China; Key Laboratory of Groundwater Contamination Remediation, Shijiazhuang, 050061, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Institute of Hydrogeology & Environmental Geology, CAGS, Shijiazhuang, 050061, China; Key Laboratory of Groundwater Contamination Remediation, Shijiazhuang, 050061, China.
authors.forename: Le
authors.initials: L
authors.lastname: Song
authors.affiliation: Institute of Hydrogeology & Environmental Geology, CAGS, Shijiazhuang, 050061, China; Key Laboratory of Groundwater Contamination Remediation, Shijiazhuang, 050061, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000032:analysis / Q000737:chemistry; D002857:Chromium / Q000032:analysis / Q000737:chemistry; D060587:Groundwater / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D017641:Zeolites / Q000737:chemistry*
chemical_list: D002104:Cadmium; D002857:Chromium; D007501:Iron; D019216:Metals, Heavy; D062065:Wastewater; D014874:Water Pollutants, Chemical; D017641:Zeolites
keywords: Heavy metals; Removal mechanism; Synthesis; Zeolite-supported microscale zero-valent iron (Z-mZVI)