Effect of fulvic acid co-precipitation on biosynthesis of Fe(III) hydroxysulfate and its adsorption of lead

Yanping Bao, Jinhao Lai, Yishun Wang, Zheng Fang, Yongshi Su, Daniel S. Alessi, Nanthi S. Bolan, Xiaolian Wu, Yan Zhang, Xueding Jiang, Zhihong Tu, Hailong Wang

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2 Citations (Scopus)

Abstract

Iron (III) co-precipitation with dissolved organic matter (DOM) is pervasive in many natural environments. However, the effects of DOM on the formation of Fe(III) hydroxysulfate (FHS) and its environmental implications are poorly understood. In this study, fulvic acid (FA) was used as a model DOM compound, and experiments were devised to investigate the effects of FA on the formation of FHS. In addition, the Pb(II) adsorption capabilities of FHSs biosynthesized under various FA dosages, including kinetics and sorption isotherm experiments, were conducted. These experiments showed that co-precipitation of FA promoted the formation of Fe-FA composites, FA-doped schwertmannite, and small particles of jarosite. Co-precipitates are more enriched in carboxyl (–COOH) functional groups due to their preferential binding with FHS. The adsorption kinetics, isotherms and mechanisms of Pb onto the biosynthesized FHSs were then comprehensively characterized and modeled. Though the specific surface area decreased with increasing FA loading, the introduction of FA into FHSs increased Pb(II) adsorption, with the highest concentration of FA addition improving the removal capacity of Pb(II) to 91.54%. Kinetics studies and intra-particle diffusion models indicated that the adsorption of Pb(II) onto the FHSs was correlated with the number of active sites, and two adsorption steps: surface adsorption and the diffusion of Pb(II) in channels inside the biosynthesized FHSs, are suggested. The adsorption mechanism was attributed to cation exchange between Pb(II) and –OH and –COOH functional groups, and the co-precipitated FA provided additional sites for Pb(II) adsorption by FHS.

Original languageEnglish
Article number118669
JournalEnvironmental Pollution
Volume295
DOIs
Publication statusPublished - 15 Feb 2022

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