Use of cyclodextrins as an environmentally friendly extracting agent in organic aged-contaminated soil remediation

The removal of Polycyclic Aromatic Hydrocarbons (PAHs) from soil using pure water is quite ineffective due to their low aqueous solubility. Most of present processes are based on organic cosolvents or surfactants, leading to potential environmental hazard. Addition of cyclodextrin (CD) in aqueous washing solutions has been shown to increase the removal efficiency several times, while being non-toxic agents. Herein are investigated the effectiveness of cyclodextrins to remove PAHs occurring in industrially aged-contaminated soil. beta-cyclodextrin (BCD), hydroxypropyl-beta-cyclodextrin (HPCD) and methyl-beta-cyclodextrin (MCD) solutions were used for soil flushing in column test or batch experiments to evaluate some influent parameters that can significantly increase the removal efficiency. The process parameters chosen were CD concentration, ratio of washing solution volume to soil weight, and temperature of washing solution. These parameters were found to have a significant and almost linear effect on PAHs removal from the contaminated soil, except the temperature where no significant enhancement in PAHs extraction was observed for temperature range from 5 to 35 degrees C. Removal capacity of HPCD and MCD was higher than BCD one. The PAHs extraction enhancement factor compared to water was about 200.