High-efficiency stabilization of lead in contaminated soil by thermal-organic acid–activated phosphate rock

Ziwen Song,Likun Yang,Jin Wu,Zhuo Zhang,Canyu Luo

doi:10.1007/s11356-022-19419-0

Abstract

Phosphate rock powder (PR) has been shown to possess the potential to stabilize lead (Pb) in soil. Most of the phosphorus (P) minerals in the world are low-grade ores, making it difficult to achieve the expected stabilization effect on heavy metals. This study compared the changes in the phase composition and structure of PR and three kinds of activated phosphate rock powder (APR) (organic acid-activated PR, thermal-activated PR, and thermal-organic acid-activated PR). The stabilization effectiveness of APR on Pb-contaminated soil was evaluated by toxicity leaching procedure; the Pb products adsorbed on APR and stabilization mechanism of APR on Pb were analyzed. The results demonstrated that APR showed decreased crystallinity and 3.4-fold increase in specific surface area, and a 53.07% and 49.32% increase in soluble P content in oxalic acid-activated PR and citric acid-activated PR, respectively, when compared with those of PR. These changes improved the stabilization effect of APR on Pb-contaminated soil, in which oxalic acid-600 °C-activated PR showed the best effect, presenting 94.0-99.8% reduction in Pb leaching concentration following addition of 2-10% modifier. Product characterization after Pb adsorption on APR showed that Pb was adsorbed onto APR by forming fluoropyromophite precipitation with APR.

Highlights

With rapid urbanization and industrialization, heavy metals contamination of soil has attracted worldwide attention (Yubo et al 2020)
PR was used as a raw material to examine the effectiveness of different activation methods such as organic acid activation, thermal activation, and thermal-acid activation, and the stabilization effect of activated phosphate rock powder (APR) on potential to stabilize lead (Pb)-contaminated soil was analyzed
The results indicated that organic acid activation, thermal activation, and thermal-acid activation decreased the crystallinity of PR and increased the specific surface area of PR by making its structure porous

Summary

Introduction

With rapid urbanization and industrialization, heavy metals contamination of soil has attracted worldwide attention (Yubo et al 2020). With the development of cities, industries, and agriculture, soil contamination is becoming an increasingly serious issue. The increase in the contents of heavy metals, especially lead (Pb), in soil poses a significant threat to the environment and human health (Park et al 2011). Previous studies have shown that the Pb content in the soil of Pb-acid battery plants could be as high as 10%-30%, which poses a high risk owing to the high bioavailable Pb content (Zhang et al 2015). Effective strategies are required to remediate Pb-polluted soil

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Conclusion