Lead immobilization by phosphate in the presence of iron oxides: Adsorption versus precipitation

WATER RESEARCH

卷:179

Article

Shi, Qiantao¹  Zhang, Shujuan¹  Ge, Jie¹  Wei, Jinshan¹  Christodoulatos, Christos¹  Korfiatis, George P.¹  Meng, Xiaoguang¹ 

[1] Stevens Inst Technol, Ctr Environm Syst, Hoboken, NJ 07030 USA

关键词: Lead;    Iron oxides;    Phosphate;    Adsorption;    Precipitation;   

DOI  :  10.1016/j.watres.2020.115853

来源: Elsevier

【 摘 要 】

As a commonly used corrosion inhibitor, phosphate (PO4) has a complicated effect on the fate and transport of lead (Pb) in drinking water systems. While the formation of pyromorphite has been recognized to be the major driving force of the Pb immobilization mechanism, the role of adsorption on iron oxides is still not clear. This study aims to clarify the contributions of adsorption and precipitation to Pb removal in a system containing both iron oxides and PO4. A combination of batch experiments, X-ray absorption spectroscopy, infrared spectroscopy, and electron spectroscopy was employed to distinguish the adsorbed and precipitated Pb species. The results indicated that the adsorption of Pb on iron oxides still occurred even when the solution was supersaturated to pyromorphite (i.e., 5 mg/L P with 0.1-30 mg/L Pb in 0.01 M NaCl solution at neutral pH). In the tap water containing 0.92 mg/L P and 1 mg/L Pb, adsorption on iron oxides contributed more (62-67%) than precipitation (33-38%) in terms of Pb removal. Surprisingly, the pre-formed pyromorphite is transformed to adsorbed species after mixing with iron oxides in water for 24 h. The illustration of this transformation is important to understand the immobilization mechanisms and transport behaviors of Pb in drinking water systems after the utilization of PO4. (C) 2020 Elsevier Ltd. All rights reserved.

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