Effect of Soil Fulvic and Humic Acids on Pb Binding to the Goethite/Solution Interface: Ligand Charge Distribution Modeling and Speciation Distribution of Pb

• DOI: 10.1021/acs.est.7b05412
• Publication Date: 2018-01-10T16:15:44Z
• Authors: Juan Xiong; Liping Weng; Luuk K. Koopal; Mingxia Wang; Zhihua Shi; Lirong Zheng; Wenfeng Tan
• Keywords: Genetic algorithm; Fulvic acid

The effect of adsorbed soil fulvic (JGFA) and humic acid (JGHA) on Pb binding to goethite was studied with the ligand charge distribution (LCD) model X-ray absorption fine structure (XAFS) spectroscopy analysis. In LCD model, small JGFA particles were evenly located in Stern layer, but large JGHA distributed over layer diffuse which mainly depended diameter concentrations. Specific interactions substances (HS) modeled by inner-sphere complexes between −FeOH20.5+ −COO– HS bridges surface sites COO– groups HS. At low levels, nearly 100% bound as for both JGHA. high levels loading, Pb–goethite almost dominated entire pH range, at primary species goethite–HS–Pb acidic goethite–Pb alkaline pH. Compared JGFA, there a constant contribution about 10% linear combination fit EXAFS, using Pb–HS references, indicated that increased loading more less goethite, supported calculations.