[Relation between average oxidation state of Mn of birnessite and the amount of Pb2+ adsorbed].
Vacant sites in Mn oxides, commonly occur in soils, play an important role in their heavy metal adsorption behavior. The dependence of Pb2+ adsorption capacity for the synthesized birnessites and their d110-interplanar spacing on the respective Mn average oxidation state (AOS), and the relationship between Pb2+ adsorption and the Mn2+, H+, K+ released during adsorption were investigated. The results show that Mn AOS of birnessites apparently reflects their amount of vacant sites which largely account for the Pb2+ adsorption. Significant positive correlation between Pb2+ adsorption capacity and the Mn AOS of corresponding birnessites (r = 0.9779 > 0.6614, n = 14, alpha = 0.01), negative correlation between d110 spacing and the Mn AOS (r = -0.9035 < -0.6614, n = 14, alpha = 0.01), and significant positive correlation between Pb2+ adsorption and the Mn2+, H+, K+ released during adsorption(r = 0.9962 > 0.6614, n = 14, alpha = 0.01) are found. The vacant sites amount increases with Mn AOS for birnessites, which causes the increase of Pb2+ adsorption. Therefore, the Pb2+ adsorption capacity of birnessite is largely determined by the amount of vacant sites, from which Mn2+, H+, and K+ released during adsorption are mostly derived.
Zhao
Wei
W
College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China. aoei@webmail.hzau.edu.cn
Cui
Hao-Jie
HJ
Feng
Xiong-Han
XH
Tan
Wen-Feng
WF
Liu
Fan
F
D000327:Adsorption; D007854:Lead / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*
D017895:Manganese Compounds; D010087:Oxides; D012989:Soil Pollutants; C505018:birnessite; D007854:Lead; D008345:Manganese; C027424:manganese oxide