Comparative Activation Process of Pb, Cd and Tl Using Chelating Agents from Contaminated Red Soils

Lirong Liu, Dinggui Luo, Guangchao Yao, Xuexia Huang, Lezhang Wei, Yu Liu, Qihang Wu, Xiaotao Mai, Guowei Liu and Tangfu Xiao
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Lirong Liu: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Dinggui Luo: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Guangchao Yao: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Xuexia Huang: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Lezhang Wei: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Yu Liu: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Qihang Wu: Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China
Xiaotao Mai: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Guowei Liu: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
Tangfu Xiao: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China

IJERPH, 2020, vol. 17, issue 2, 1-15

Abstract: Adding chelating agents is a critical technique of heavy metal activation for enhancing phytoextraction through the formation of soluble metal complexes which will be more readily available for extraction. The preliminary, dynamic, equilibrium activation experiments and speciation analysis of Pb, Cd and Tl in contaminated red soils were used to select six chelates with relatively good activation performance from nine chelates, and the effects of dosage and pH on the heavy metals activation were studied systematically. Results showed that the activation of Pb, Cd and Tl by chelates reached equilibrium within 2 h, and the activation process showed three stages. Under neutral conditions, chelates had better activation performance on Pb- and Cd-contaminated soils. Except for S,S-ethylenediamine disuccinic acid (S,S-EDDS) and citric acid (CA), the maximum equilibrium activation effect (MEAE) of ethylenediaminetetraacetic acid (EDTA), N,N-bis (carboxymethyl) glutamic acid (GLDA), diethylenetriaminepentaacetic acid (DTPA) and aminotriacetic acid (NTA) was over 81%. The MEAE of Tl-contaminated soil was less than 15%. The decreasing order of the dosage of chelating agents corresponding to MEAE for three types of contaminated soils was Pb-, Cd- and Tl-contaminated soil, relating to the forms of heavy metals, the stability constants of metal–chelates and the activation of non-target elements Fe in red soil. Under acidic conditions, the activation efficiencies of chelates decreased to differing degrees in Pb- and Cd-contaminated soils, whereas the activation efficiencies of chelating agents in Tl-contaminated soils were slightly enhanced.

Keywords: heavy metal; thallium; chelating agents; phytoextraction; activation; red soil (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2020
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