Sub-CMC solubilization of dodecane by rhamnolipid in saturated porous media.
Experiments were conducted with a two-dimensional flow cell to examine the effect of monorhamnolipid surfactant at sub-CMC concentrations on solubilization of dodecane in porous media under dynamic flow conditions. Quartz sand was used as the porous medium and artificial groundwater was used as the background solution. The effectiveness of the monorhamnolipid was compared to that of SDBS, Triton X-100, and ethanol. The results demonstrated the enhancement of dodecane solubility by monorhamnolipid surfactant at concentrations lower than CMC. The concentrations (50-210 μM) are sufficiently low that they do not cause mobilization of the dodecane. Retention of rhamnolipid in the porous medium and detection of nano-size aggregates in the effluent show that the solubilization is based on a sub-CMC aggregate-formation mechanism, which is significantly stronger than the solubilization caused by the co-solvent effect. The rhamnolipid biosurfactant is more efficient for the solubilization compared to the synthetic surfactants. These results indicate a strategy of employing low concentrations of rhamnolipid for surfactant-enhanced aquifer remediation (SEAR), which may overcome the drawbacks of using surfactants at hyper-CMC concentrations.
College of Environmental Science and Engineering, Hunan University, Changsha 410082, China.|School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan 430070, China.|Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona 85721, USA.
Hua
H
Zhong
College of Environmental Science and Engineering, Hunan University, Changsha 410082, China.|Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
Hui
H
Zhang
College of Environmental Science and Engineering, Hunan University, Changsha 410082, China.|Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
Zhifeng
Z
Liu
College of Environmental Science and Engineering, Hunan University, Changsha 410082, China.|Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
Xin
X
Yang
Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona 85721, USA.
Mark L
ML
Brusseau
College of Environmental Science and Engineering, Hunan University, Changsha 410082, China.|Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
Guangming
G
Zeng
D000473:Alkanes / Q000737:chemistry; D006017:Glycolipids / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry; D017830:Octoxynol / Q000737:chemistry; D016062:Porosity; D012989:Soil Pollutants / Q000737:chemistry / Q000302:isolation & purification*; D012995:Solubility; D013501:Surface-Active Agents / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*
D000473:Alkanes; D006017:Glycolipids; D012989:Soil Pollutants; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; C418382:rhamnolipid; C007548:n-dodecane; D017830:Octoxynol