Synchronous stabilization of As, Cd, and Pb in soil by sustained-release of iron-phosphate

Zhi Jiang; Kai Nie; Lin Yu; Chukwuma Arinzechi; Feiping Zhao; Qi Liao; Zhihui Yang; Mengying Si; Weichun Yang

doi:10.1016/j.scitotenv.2022.161369

Synchronous stabilization of As, Cd, and Pb in soil by sustained-release of iron-phosphate

Sci Total Environ. 2023 Apr 1:867:161369. doi: 10.1016/j.scitotenv.2022.161369. Epub 2023 Jan 7.

Authors

Zhi Jiang¹, Kai Nie¹, Lin Yu¹, Chukwuma Arinzechi¹, Feiping Zhao², Qi Liao², Zhihui Yang², Mengying Si³, Weichun Yang⁴

Affiliations

¹ School of Metallurgy and Environment, Central South University, Changsha 410083, PR China.
² School of Metallurgy and Environment, Central South University, Changsha 410083, PR China; Chinese National Engineering Research Centre for Control & Treatment of Heavy Metal Pollution, Changsha 410083, PR China.
³ School of Metallurgy and Environment, Central South University, Changsha 410083, PR China; Chinese National Engineering Research Centre for Control & Treatment of Heavy Metal Pollution, Changsha 410083, PR China. Electronic address: simysmile@csu.edu.cn.
⁴ School of Metallurgy and Environment, Central South University, Changsha 410083, PR China; Chinese National Engineering Research Centre for Control & Treatment of Heavy Metal Pollution, Changsha 410083, PR China. Electronic address: yang220@csu.edu.cn.

PMID: 36626993
DOI: 10.1016/j.scitotenv.2022.161369

Abstract

Anionic arsenic (As) exhibits geochemical behavior opposite to those of cationic cadmium (Cd), and lead (Pb), which makes the synchronous remediation of As, Cd, and Pb challenging. The synchronous stabilization of As, Cd, and Pb to form Cd/Pb-phosphate and iron‑arsenic precipitates is a promising strategy. However, the effectiveness of soluble phosphate or iron-based materials is limited by the activation of Cd, Pb, or As, while low mobility hinders insoluble particles. In this study, we developed an amorphous structure that releases iron and phosphate at a sustained rate. Thus, the stabilization efficiencies of NaHCO₃-extractable As, DTPA-extractable Cd and Pb reached 44.6 %, 40.8 %, and 48.1 %, respectively. The proportion of residual fraction of As, Cd, and Pb increased by 12.1 %, 14.5 %, and 36.4 %, respectively, after 28 d. Ferrihydrite was chosen as the soil component to monitor the chemical behavior and speciation transformation of As, Cd, and Pb in the reaction. During the process, the released iron directly reacted with dissolved As to form iron‑arsenic precipitation and phosphate directly reacted with Cd/Pb to form Cd/Pb-phosphate precipitation. Simultaneously, phosphate replaced the adsorbed As and transformed into a dissolved state, which could be re-precipitated with the released iron ions. Thus, this study provides a reliable strategy for the remediation of As, Cd, and Pb combined pollution in soil.

Keywords: Cd/Pb-phosphate; Iron‑arsenic coprecipitation; Multi-metal contaminated soil; Soil remediation.