SOIL FLUSHING USING COLLOIDAL GAS APHRON SUSPENSIONS GENERATED FROM APLANT-BASED SURFACTANT

Natural surfactant solutions obtained from the fruit pericarps of Sapi ndus mukorossi, commonly known as Ritha or soapnut, are tested for the ir ability to remove hydrophobic organic compounds (HOCs) from soil. C olloidal gas aphron (CCA) suspensions generated using the surfactant a re used in this study to flush an HOC from a representative soil. Soil is spiked with a chlorinated hydrocarbon, hexachlorobenzene (HCB), se rving as a model HOC representative of contamination at a Superfund si te north of Baton Rouge, LA. The recovery of HCB from soil columns usi ng CGA suspensions was considerably larger than that for a waterflood. HCB recoveries in the effluent reached a maximum by the fifth pore vo lume and remained fairly constant for soils contaminated with high lev els of HCB. This maximum HCB concentration in the column effluent was proportional to HCB solubility in the corresponding surfactant solutio ns. Natural surfactant performed marginally better in the form of conv entional solutions than CGA suspensions at similar concentration in re covering HCB. HCB removal increased with increasing surfactant concent ration due to increased aqueous solubility. The pressure buildup acros s the soil column remained fairly low when natural surfactant was used at concentrations up to 1%. Alternating the flushing media between CG A and water neither enhanced the recovery of HCB nor changed the press ure buildup across the soil column. (C) 1998 Elsevier Science B.V.