Relation of lead adsorption on birnessites with different average oxidation states of manganese and release of Mn{sup}(2+)/H{sup}+/K{sup}+

摘要

The characteristics of Pb{sup}(2+) adsorption on the surface of birnessites with different average oxidation states (AOS) of Mn, synthesized under acidic and alkali conditions, were investigated. The results indicated that the amount of adsorbed Pb{sup}(2+) increased with the increase of Mn AOS in birnessites. The amount of Pb{sup}(2+) adsorbed positively correlated with the amount of released Mn{sup}(2+), H{sup}+, and K{sup}+ (r = 0.9962 > 0.6614, n = 14, α = 0.01). The released Mn{sup}(2+), H{sup}+, and K{sup}+ were derived mostly from the corresponding cations adsorbed on the vacant sites. The maximum amount of adsorbed Pb{sup}(2+) increased with the increasing vacant cation sites, leading to an increase of the total amount of released Mn{sup}(2+), H{sup}+, and K{sup}+, and the increased likelihood for two Pb{sup}(2+) adsorbed in the region of one side of a vacant site.