왕수를 이용한 중금속 오염토양에서의 추출방안 연구

Abstract

Aqua regia extraction for the quantification of heavy metals and As in contaminated soils was investigated as one of preliminary steps for on-site monitoring using sensor technology. Soil samples were taken from closed railway depot, closed mines, and closed refinery and various extraction conditions including 30oC/15 min, 30oC/30 min, 30oC/60 min, 30oC/120 min, 80oC/15 min, 80oC/30 min, 80oC/60 min, 80oC/120 min were tested. The optimal extraction condition was determined as 80oC/60 min because the extraction efficiencies of Zn were relatively low and did not reach the targeted level (80-100% of original concentrations) for 30oC conditions. It was found that the fractionation of heavy metals and As using the sequential extraction method was useful to understand the degree of metal extraction. In order to enhance the extraction efficiency within short extraction time, ultrasound technology using a 20 kHz horn-type sonicator was additionally used for 30oC/15 min. It was revealed that ultrasound could significantly enhance the extraction efficiency and pulsed irradiation showed higher efficiency than continuous irradiation due to the less formation of bubble clouds. However high temperature condition (80oC) was required to achieve high extraction efficiency for Zn in spite of the use of ultrasound.