AQUEOUS SOLUBILITY ENHANCEMENT AND DESORPTION OF HEXACHLOROBENZENE FROM SOIL USING A PLANT-BASED SURFACTANT

A plant-based surfactant extracted from fruit pericarps of Sapindus mu korossi (Ritha) is proposed for remediation of contaminated soil from a local hazardous waste site. Natural surfactants can be prepared usin g a very simple water extraction of fruit pericarp powder. Natural sur factant solutions are employed to enhance the aqueous solubility of a hydrophobic organic compound, hexachlorobenzene (HCB), and to desorb H CB from soils in batch and one-dimensional flow-through soil column ex periments. The solubility of HCB in natural surfactant solutions incre ased linearly with surfactant concentration beyond the critical micell e concentration. The mass of dry Ritha powder required to solubilize 1 mg of HCB in 1 liter of water was comparable to sodium dodecylsulfate solution and other commercial surfactants. HCB concentration in the a queous solutions approached 90% of the HCB solubility in the respectiv e natural surfactant solutions when soils contaminated to high levels were used for desorption. HCB recovery was up to 90% of the total HCB for soils contaminated with lower levels. Desorption behavior observed for natural surfactant solutions was similar to SDS solutions. Natura l surfactant solutions performed more efficiently than a simple water hood in recovering HCB from one-dimensional soil columns. The HCB conc entration in the effluent was found to be as high as 80% of the surfac tant-enhanced HCB solubility in respective solutions. The results of t his study provide a strong case for pursuing natural surfactant soluti ons in further research. (C) 1997 Elsevier Science Ltd.