Enhancing the dissolution of PCE with the mixed cyclodextrin-ethanol solution for aquifer remediation

Groundwater contaminated by dense non-aqueous phase liquids (DNAPLs) such as chlorinated hydrocarbons is difficult to remediate. The combination of flushing agents has a synergistic solubilization effect on the removal of DNAPLs. However, the solubilization mechanisms of DNAPLs under the mixed flushing agent treatment remains poorly understood. In this work, the dissolution process of tetrachloroethylene (PCE) in Hydroxypropyl-β-cyclodextrin (HPCD)-ethanol mixed solution system was observed through one-dimensional (1D) capillary experiments. The mixed HPCD-ethanol solution has a synergistic solubilization effect on PCE dissolution, and the synergistic solubilization function curve of PCE was derived. Furthermore, the mixed HPCD-ethanol solution was used to investigate PCE removal process within a two-dimensional (2D) transparent micromodel. The results demonstrate that the combination of flushing agents significantly enhance PCE removal efficiency. The maximum dissolution rate of PCE under the flushing of the mixed solution was increased by a factor of 2-6 compared to single solution systems of ethanol or HPCD, and the flushing time was reduced by 40 %.