title: Influence of multi-step washing using Na2EDTA, oxalic acid and phosphoric acid on metal fractionation and spectroscopy characteristics from contaminated soil.
abstract: A multi-step soil washing test using a typical chelating agent (Na2EDTA), organic acid (oxalic acid), and inorganic weak acid (phosphoric acid) was conducted to remediate soil contaminated with heavy metals near an arsenic mining area. The aim of the test was to improve the heavy metal removal efficiency and investigate its influence on metal fractionation and the spectroscopy characteristics of contaminated soil. The results indicated that the orders of the multi-step washing were critical for the removal efficiencies of the metal fractions, bioavailability, and potential mobility due to the different dissolution levels of mineral fractions and the inter-transformation of metal fractions by XRD and FT-IR spectral analyses. The optimal soil washing options were identified as the Na2EDTA-phosphoric-oxalic acid (EPO) and phosphoric-oxalic acid-Na2EDTA (POE) sequences because of their high removal efficiencies (approximately 45 % for arsenic and 88 % for cadmium) and the minimal harmful effects that were determined by the mobility and bioavailability of the remaining heavy metals based on the metal stability (IR) and modified redistribution index ([Formula: see text]).
authors: Key Laboratory for Water and Sediment Sciences of Ministry of Education, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing, 100875, People's Republic of China.
authors: Meng
authors: M
authors: Wei
authors: Key Laboratory for Water and Sediment Sciences of Ministry of Education, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing, 100875, People's Republic of China. jeffchen@bnu.edu.cn.
authors: Jiajun
authors: J
authors: Chen
mesh_terms: D001151:Arsenic / Q000302:isolation & purification*; D002104:Cadmium / Q000302:isolation & purification*; D002614:Chelating Agents / Q000737:chemistry; D005591:Chemical Fractionation; D004492:Edetic Acid / Q000737:chemistry*; D004787:Environmental Pollution / Q000517:prevention & control; D019216:Metals, Heavy; D008906:Mining; D009930:Organic Chemicals; D010070:Oxalates / Q000737:chemistry*; D010756:Phosphoric Acids / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000302:isolation & purification*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002614:Chelating Agents; D019216:Metals, Heavy; D009930:Organic Chemicals; D010070:Oxalates; D010756:Phosphoric Acids; D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D004492:Edetic Acid; C030242:phosphoric acid; D001151:Arsenic
keywords: FT-IR and XRD evidence; Fraction redistribution; Metal stability; Multi-step washing