Species and Distribution of Arsenic in Soil After Remediation by Electrokinetics Coupled with Permeable Reactive Barrier
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Species and Distribution of Arsenic in Soil After Remediation by Electrokinetics Coupled with Permeable Reactive Barrier Dongli Ji & Jing Zhang & Fansheng Meng & Yeyao Wang & Daohong Zhang
Received: 6 December 2019 / Accepted: 23 November 2020 # Springer Nature Switzerland AG 2020
Abstract Arsenic-polluted soil from a mining area in China was treated by electrokinetics coupled with permeable reaction barrier (EK/PRB). Batch tests with PRB media of zero valent iron (ZVI) under electric potential of 2 V cm−1 for 120 h were conducted. Species and distribution of arsenic in soil after remediation were investigated to evaluate the removal mechanisms of arsenic. Results showed that ZVI-PRB was the dominant role in the removal of arsenic in the EK/PRB systems. Arsenic transferring toward the anode was greater than cathode, due to the negatively charged arsenic anions which moved to the anode chamber by electromigration. Pentavalent arsenic (As(V)) in soil could not be reduced to more poisonous trivalent arsenic (As(III)), no matter if it were treated by EK alone or EK/ ZVI-PRB. The surface characterization of ZVI, which was carried out using X-ray photoelectron spectrometry (XPS), showed that the ratio of As(V)/As(III) on the surface of PRB media was lower than that in the initial soil; no As(0) was detected on the surface of used ZVI, which indicates that arsenic was removed by surface D. Ji (*) : D. Zhang School of Environmental and Municipal Engineering, Tianjin Chengjian University, No. 26, Jinjing Road, Xiqing District, Tianjin 300384, China e-mail: [email protected] J. Zhang Tianjin Center, China Geological Survey, Tianjin 300170, China F. Meng : Y. Wang Chinese Research Academy of Environmental Sciences, Beijing 100012, China
adsorption/precipitation on ZVI-PRB, accompanied by As(V) partially reduced to As(III). The results reported in this study will be beneficial to optimizing the design of batch EK/PRB system and to enlarging the field-scale system. Keywords Arsenic species . Polluted soil . Electrokinetics . Permeable reaction barrier . Removal mechanisms
1 Introduction Arsenic has attracted broad concerns due to its high toxicity and strong carcinogenicity to human beings and animals. Release from the arsenic-enriched minerals is the primary natural source. The main contamination sources of arsenic are related to human activities, including mining and smelting, industrial processes, and agricultural practices (Ruíz-huerta et al. 2017; Garcíacarmona et al. 2017). The decomposition, migration, and diffusion of arsenic-containing substances have resulted in soil arsenic pollution. According to the national survey bulletin on soil heavy metal pollution, the overall over-standard rate of soil in China is 16.1%, second only to cadmium and nickel (Zhao et al. 2010). A joint survey by Chinese and Swiss researchers showed that nearly 20 million people in China lived in areas at high risk of soil arsenic contamination (Rodríguezlado et al. 2013; Li et al. 2017a). Furthermore, heavy metals such as arsenic, copper
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