Pb2+ adsorption on birnessite affected by Zn2+ and Mn2+ pretreatments

摘要: Lead contamination is ubiquitous, and much attention has been paid due to its toxicity. The phyllomanganate birnessite the most common Mn oxide in soils. MnO6 octahedral layers may have significant vacancies hexagonal birnessites. Among heavy metal ions, birnessites possess greatest adsorption affinity capacity for Pb2+. aim of this study was understand relationship between vacant sites Pb2+ adsorption. Birnessite synthesis achieved by reduction potassium permanganate a strong acidic medium. Synthetic then treated with Mn2+ or Zn2+ at different concentrations. Isothermal on before after treatments measured solid-to-liquid ratio approximately 1.67 g/L, concentrations ranged from 0 10 mmol/L an ionic strength 0.1 mol/L NaNO3. amount adsorbed released during whole process were obtained comparison control group without adding H+ determined recorded additions standard HNO3/NaOH solutions. average oxidation state (AOS) d(110)-interplanar spacings remained almost unchanged as concentration treating increased, indicating number sites, whereas maximum decreased 3,190 2,030 mmol/kg presence sites. AOS’s Mn2+-treated ions added oxidized Mn3+ ions. spacing increased 0.14160 0.14196 nm, indicative Moreover, 1,332 mmol/kg, decrease being greater than that corresponding Zn2+-treated Most birnessite, portion located above below which did not affect remaining migrating occupy In contrast, are only largely