Abstract
Due to their biodegradability and low toxicity bio-based surfactants are very promising for use in remediation technologies, particularly for hydrocarbon contaminated soils. To enhance the application of surfactant-based technologies for remediation of organic contaminated sites, it is important to have a better understanding of the surfactant transport and retention mechanisms involved in this process, as they will impact the remediation efficiency. In this work, transport and retention mechanisms of an industrial bio-based nonionic sucrose ester surfactant were investigated through batch and column experiments, carried out on sandy porous media under saturated steady state flow conditions. Column transport experiments were conducted at surfactant concentrations ranged from 1 to 10 CMC (critical micellar concentration), for two distinct Darcy flow rates (0.35 and 0.70 cm.min-1). Surfactant transport and retention parameters were estimated by fitting a convection-diffusion transport model (implemented on HYDRUS-1D code) to the observed transport breakthrough curves, in order to provide an adequate description and understanding of the mechanisms involved in the transport and adsorption of these compounds through porous media. The results obtained from column experiments performed under high flow rate combined with high surfactant concentration provided the best conditions for high surfactant recovery in the effluent and low surfactant adsorption rate onto the sand. Numerical HYDRUS-1D simulations permitted to quantify surfactant transport behavior and provided attachment coefficients several order of magnitude greater than detachment coefficients, indicating that surfactant retention was an irreversible process.
