title: Characterization of Co-doped birnessites and application for removal of lead and arsenite.
abstract: Nanostructured Co-doped birnessites were successfully synthesized, and their application for the removal of Pb(2+) and As(III) from aquatic systems was investigated. Powder X-ray diffraction, chemical analysis, nitrogen physical adsorption, field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystal structure, chemical composition, micromorphologies and surface properties of the birnessites. Doping cobalt into the layer of birnessite had little effect on its crystal structure and micromorphology. Both chemical and XPS analyses showed that the manganese average oxidation state (Mn AOS) decreased after cobalt doping. The Co dopant existed mainly in the form of Co(III)OOH in the birnessite structure. Part of the doped Co(3+) substituted for Mn(4+), resulting in the gain of negative charge of the layer and an increase in the content of the hydroxyl group, which accounted for the improved Pb(2+) adsorption capacity. The maximum capacity of Pb(2+) adsorption on HB, CoB5, CoB10 and CoB20 was 2538 mmol kg(-1), 2798 mmol kg(-1), 2932 mmol kg(-1) and 3146 mmol kg(-1), respectively. The total As(III) removal from solution was 94.30% for CoB5 and 100% for both CoB10 and CoB20, compared to 92.03% for undoped HB, by oxidation, adsorption and fixation, simultaneously.
authors.affiliation: Key Laboratory of Subtropical Agriculture Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, No 1 Nanhu Shizishan Street, Wuhan 430070, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yin
authors.forename: Xionghan
authors.initials: X
authors.lastname: Feng
authors.forename: Guohong
authors.initials: G
authors.lastname: Qiu
authors.forename: Wenfeng
authors.initials: W
authors.lastname: Tan
authors.forename: Fan
authors.initials: F
authors.lastname: Liu
mesh_terms: D000327:Adsorption; D018053:Arsenites / Q000302:isolation & purification*; D003035:Cobalt / Q000737:chemistry*; D004787:Environmental Pollution / Q000517:prevention & control*; D007854:Lead / Q000302:isolation & purification*; D049329:Nanostructures / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*
chemical_list: D018053:Arsenites; D010087:Oxides; C505018:birnessite; D007854:Lead; D003035:Cobalt; C015001:arsenite