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| Effects of folic acid and methionine on chelating agents in the removal of heavy metals |
| Received:April 07, 2018 |
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| KeyWord:contaminated soil;heavy metals;eco-friendly agents;organic acid;composite washing |
| Author Name | Affiliation | E-mail | | PENG Ya-xi | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | | | ZHANG Shi-rong | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | rsz01@163.com | | WANG Yi-jun | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | | | ZHONG Qin-mei | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | | | FENG Can | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | |
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| Abstract: |
| Soil washing is a promising and efficient method for remediating metal-contaminated soils. To explore the effects of citric acid (CA), ammonium citrate(AC), and 2-phosphonobutane-1, 2, 4-tricarboxylic acid(PBTCA)on cadmium, lead, and zinc removal, batch soil washing tests were carried out with two assistant reagents, namely, folic acid(FA)and methionine(Met). Results showed that the addition of FA or Met significantly improved the heavy metal removal efficiencies(P<0.05). The maximum improvements in soil heavy metal removal were 10.45% and 12.08% for Cd and Zn, respectively, with the addition of FA under acidic conditions compared with CA alone, and 19.65% for Pb removal with the addition of FA compared with AC alone. The augmentations to removal rates in soil Cd, Pb, and Zn were 0.22%, 8.60%, and 7.09%, respectively, via Met addition compared with PBTCA alone. The metal removal efficiencies increased with increasing contact time and then tended to plateau when washing occurred with washing agents combined by one assistant reagent and one chelating agent. The highest removal efficiencies of Cd, Pb, and Zn for compounded extraction agent reached 61.98%, 76.57%, and 49.20%, respectively, at pH 4.0 and a leaching time of 120 min. The exchangeable, reducible, and oxidizable fractions of Cd, Pb, and Zn in the soil decreased significantly after washing with the combined assistant reagents and chelating reagents. These findings indicate that the addition of FA or Met with chelating agents could enhance the removal of soil heavy metals. |
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