Abstract
Column tests were conducted to investigate the optimal condition of surfactant solution pH that can affect the removal efficiency in surfactant-assisted remediation. Toluene and 1,2,4-trichlorobenzene were chosen as the model hydrophobic substances. Two Iowa soils, Fruitfield sand and Webster clay loam, were leached with solutions of 4%(v/v) sodium diphenyl oxide disulfonate (DOSL, trade name Dowfax 8390), or 4%(v/v) trideceth-19-carboxylic acid (TDCA, trade name Sandopan JA36), or 4% (v/v) octylphenoxypoly ethoxyethanol (OPEE, trade name Triton X100). The test results revealed that a maximum removal of toluene and 1,2,4-trichlorobenzene was obtained at pH 10 of surfactant solution, and maximum recoveries of added toluene (94%) or 1 ,2,4- trichlorobenzene (97 %) were obtained for DOSL surfactant solution in Fruitfield sandy soil column. Increased removal efficiency by pH control of both toluene and 1,2,4trichlorobenzene was 16% and 20% for DOSL with Fruitfild sandy soil, respectively. In addition, the maximum recoveries of added toluene or I ,2,4-trichlorobenzene were 89% and 93% for DOSL surfactant solution in Webster clay loam soil column. The maximum increase of toluene and 1,2,4-trichlorobenzene removal was 26% and 19% for DOSL with Webster clay loam soil, respectively. These experimental results indicate that maintaining a high pH surfactant solution in surfactant-assisted remediation is desirable for efficient removal of NAPLs from contminated soils.
계면활성제를 이용한 오염복원에 있어서 제거효율에 영향을 주는 계면활성제 용액 pH의 최적범위를 조사하기 위하여 주상실험이 수행되었다. 톨루엔과 1,2,4-trichlorobenzene이 소수성 유기 화합물로서 선택되었다. 4%(v/v)의 sodium diphenyl oxide disulfonate(DOSL), trideceth-19-carboxylic acid(TDCA), octylphenoxypoly ethosye-thanol(OPEE)을 사용하여 두 종류의 아이오와 토양(Fruitfield sand, Webster clay loam)에 대한 용출실험을 수행하였다. 실험결과, 톨루엔과 1,2,4-trichlorobenzene의 제거효율은 계면활성제 용액 pH 10에서 나타났고, Furifield 사질토양에서 DOSL을 이용한 경우 최대 제거효율은 각각 94%, 97%였다. Fruitfield 사질토양에서 DOSL을 사용한 경우, pH 조절에 의하여 증가된 톨루엔과 1,2,4-trichlorobenzene의 제거효율은 각각 16%와 20%였다. Webster clay loam에서 DOSL을 이용한 경우 최대 제거효율은 각각 89%, 93%였다. Webster clay loam에서 DOSL을 사용한 경우, pH 조절에 의하여 증가된 톨루엔과 1,2,4-trichlorobenzene의 제거효율은 각각 26%와 19%였다. 이러한 실험결과는 NAPLs로 오염된 토양을 복원하는데 있어서 계면활성제 용액의 pH를 높게 유지하는 것이 바람직하다는 것을 의미한다.