Chemical Extraction of Arsenic from Contaminated Soils in the Vicinity of Abandoned Mines and a Smelting Plant Under Subcritical Conditions

Abstract

Under subcritical conditions, we studied the chemical extraction of arsenic (As) from contaminated soils that were sampled from the vicinity of abandoned mines and a smelting plant in South Korea. The total initial concentrations of As in the soil samples from the Myungbong and Cheongyang mines and the Janghang smelting plant were 298.6, 145.6, and 103.7 mg/kg, respectively. X-ray photoelectron spectroscopy analysis showed that the species of As identified in the soil was As(+V), including As 2 O 5 and AsO 4 3− .At 20 • C, only 27.4, 26.5, and 40.1% of the total As was extracted from the Myungbong, Cheongyang, and Janghang soil samples, respectively, with 100 mM of NaOH. As the temperature was increased to 300 • C, the extraction efficiencies remarkably increased. However, to achieve the complete extraction of As from the soils, 100 mM of citric acid, EDTA, or NaOH was needed at 200, 250, or 300 • C. Extraction with subcritical water at 300 • C resulted in incomplete extraction of As from the soils. The results of these experiments indicate that extraction mechanisms other than oxidative dissolution of As(+III) species may be responsible for the enhancement of As extraction. Our results suggest that subcritical water extraction combined with extracting reagents can effectively remediate As-contaminated soil regardless of the As species.

Impact of Irrigation with Wastewater on Accumulation of Heavy Metals in Phaseolus vulgaris L. and Its Remediation

“…Synthetic chelating agents, such as ethylenediaminetetraacetic acid (EDTA), are the most effective chelating agents used for heavy metal removal because they have a strong chelating ability for different metals (Jean-Soro et al 2012;Oh and Yoon 2014).…”