한국지하수토양환경학회 추계학술발표회 및 통합 10주년 기념 국제심포지엄
2010년 10월 14-15일 한양대학교
Chemical washing of As-contaminated soil at elevated temperatures
오석영
1․김학엽
2․김수미
2
1
울산대학교 건설환경공학과,
2(주)대일이앤씨
e-mail :
요 약 문
Arsenic can be existed in various minerals forms in natural environment. Among them, approximately 60% are arsenates(As(+Ⅴ)O
43-
) and others include arsenite(As(+Ⅲ)O
33-
), Arsenide(As(-Ⅲ)), sulfides elemental As, and organic arsenic compounds.
Soil washing involves water-based systems to separate contaminants sorbed onto soil particles from bulk soil, and results in separation, segregation, and volume reduction of hazardous materials. Washing reagents may include leaching agents, surfactants, chelating agents, diluted acid/base solutions, pH-adjusted water to enhance the removal of contaminants from soil.
In soil washing experiments, three different types of washing agent were used; EDTA, citric acid, and NaOH. EDTA and citric acid are typical chelating agent and weak acid and NaOH is inexpensive and effective for As extraction.
The results of soil washing for As with 100mM of NaOH, 30% of As in the soil was removed. In contrast, EDTA and citric acid did not effectively extract As from the soil, whit showing less than 10%
of extraction efficiency. However, as temperature increased, the extraction efficiency of EDTA and citiric acid was accordingly increased, showing approximately 40% at 200℃. With NaOH, 42% of extraction efficiency was obtained at 150-200℃. Control washing experiments with deionized water showed that the effect of temperature on the extraction of As from the soil was much more significant than the effect of types and concentrations of washing reagent at 150-200℃.
Key words : arsenic, soil, extraction, NaOH, EDTA, citric acid, temperature
