Simultaneous reduction of available arsenic and cadmium in contaminated soil by iron-modified fly ash

ABSTRACT

Arsenic (As) and cadmium (Cd) co-contamination in the soil is a serious global health concern. Three iron-modified fly ash (FA) composites were synthesised, including FA-supported nanoscale zero-valent iron (FA-nZVI), FA-supported FeCl₃ (FA-FeCl₃) and FA-supported Fe-oxyhydroxide sulphate (FA-FeOS) for remediation of As and Cd co-contaminated soil. Soil incubation experiments were conducted to evaluate the effects of iron-modified FA on the soil pH, availability and geochemical fractions of As and Cd. The results showed that FA and FA-nZVI significantly (P < 0.05) increased the soil pH, but FA-FeCl₃ and FA-FeOS decreased the soil pH in general. FA, FA-nZVI, FA-FeCl₃ and FA-FeOS decreased the concentration of available As by 15.13∼21.22%, 46.20∼46.66%, 30.02∼38.09% and 12.05∼30.50%, respectively. However, only FA and FA-nZVI decreased the concentration of available Cd by 4.85∼26.09% and 37.74∼52.18%, respectively. The results showed that FA-nZVI was the most effective amendment for simultaneous immobilisation of As and Cd. Besides, FA-nZVI stimulated the transformation of As and Cd from reactive states to less reachable states to decrease the toxicity of As and Cd in soil. In conclusion, FA-nZVI is a potential amendment for soil remediation in As and Cd co-contaminated soil.

KEYWORDS:

• Trace elements
• coal-based solid waste
• nanoscale zero-valent iron
• soil stabilisation
• geochemical fractions

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the University-level Key Project of Anhui University of Science and Technology (xjzd2020-04), Key Project of Education Department of Anhui Province (KJ2021a0423), Funded by the Research Foundation of the Institute of Environment-friendly Materials and Occupational Health (Wuhu), Anhui University of Science and Technology (ALW2020YF15), and National Natural Science Foundation of China (41572333).

Notes on contributors

Min Chen

Min Chen is a Ph.D. Student at Anhui University of Science and Technology.

Ying Liu

Ying Liu is a Ph.D. at Anhui University of Science and Technology.

Di Zhang

Di Zhang is a postgraduate student at Anhui University of Science and Technology.

Jianming Zhu

Jianming Zhu is a postgraduate student at Anhui University of Science and Technology.

Yazhen Xing

Yazhen Xing is an engineer at the Institute of Environment-friendly Materials and Occupational Health, Anhui University of Science and Technology.

Xiaoyang Chen

Xiaoyang Chen is a Professor at Anhui University of Science and Technology.