Site contamination is a global concern due to the potential risks for human health and ecosystem quality. The peculiar physical and chemical characteristics of contaminants make the comprehension and prediction of their distribution in soil and subsoil particularly complex, which make selecting the correct remediation strategy increasingly daunting. As a matter of fact, the traditional remediation systems (like as pump-and-treat) have shown strong limitation especially in the attainment of low regulatory limits. Therefore, a significant regard is paid to the development of technologies able to mobilize contaminants particularly in the areas characterized by very limited permeability. Moreover, remediation processes are negatively affected by the low aqueous solubility of some contaminants; although, their availability can be enhanced by the addition of surfactants. These compounds are organic molecules that can be chemically and biologically produced. Surfactants contain both hydrophilic and hydrophobic groups, thus reducing surface and interfacial tensions of immiscible fluids and increasing the solubility and sorption of hydrophobic organic and inorganic compounds. The aim of the study is the experimental evaluation of different commercial surfactants for enhancing the mobilization of sorbed contaminant from solid substrate. In this context, a solution has been contaminated with toluene as a Non-Aqueous Phase Liquid (NAPL); Pine Wood Biochar (PWB) has been selected, as solid substrate, due to its high affinity toward BTEX (Silvani et al., 2017); and a 4% v/v of surfactant in distillated water was prepared as washing/ flushing solution. Preliminarily, kinetic and isothermal tests have been carried out in batch reactors to verify if the surfactant decreases the adsorption capacity of PWB with respect to toluene. The amount of adsorbed contaminant (mg/g) has been reduced to an approximately 50% which confirmed the affinity between surfactant and toluene. Secondly, the test has been run also in column, to simulate secondary source of contamination. The fixed bed column was filled with inert sand mixed with PWB (4% w/w) and saturated with 10 mg/L of toluene. After achieving equilibrium conditions (when the concentration of toluene in the outlet was equal to the inlet), the column has been flushed first with distillated water and then with surfactant. The results for the first investigated surfactant demonstrate that it has a high efficiency to increase mobility of contaminant. Experiments on another surfactant is ongoing.

Evaluation of surfactant as a useful tool for Groundwater Remediation / Amanat, Neda; Rossi, Marta Maria; Petrangeli Papini, Marco. - (2019). (Intervento presentato al convegno AquaConSoil 2019. 15th International Conference on Sustainable Use and Management of Soil, Sediment and Water Resources tenutosi a Antwerp; Belgium).

Evaluation of surfactant as a useful tool for Groundwater Remediation

Amanat, Neda
;
Rossi, Marta Maria;Petrangeli Papini, Marco
2019

Abstract

Site contamination is a global concern due to the potential risks for human health and ecosystem quality. The peculiar physical and chemical characteristics of contaminants make the comprehension and prediction of their distribution in soil and subsoil particularly complex, which make selecting the correct remediation strategy increasingly daunting. As a matter of fact, the traditional remediation systems (like as pump-and-treat) have shown strong limitation especially in the attainment of low regulatory limits. Therefore, a significant regard is paid to the development of technologies able to mobilize contaminants particularly in the areas characterized by very limited permeability. Moreover, remediation processes are negatively affected by the low aqueous solubility of some contaminants; although, their availability can be enhanced by the addition of surfactants. These compounds are organic molecules that can be chemically and biologically produced. Surfactants contain both hydrophilic and hydrophobic groups, thus reducing surface and interfacial tensions of immiscible fluids and increasing the solubility and sorption of hydrophobic organic and inorganic compounds. The aim of the study is the experimental evaluation of different commercial surfactants for enhancing the mobilization of sorbed contaminant from solid substrate. In this context, a solution has been contaminated with toluene as a Non-Aqueous Phase Liquid (NAPL); Pine Wood Biochar (PWB) has been selected, as solid substrate, due to its high affinity toward BTEX (Silvani et al., 2017); and a 4% v/v of surfactant in distillated water was prepared as washing/ flushing solution. Preliminarily, kinetic and isothermal tests have been carried out in batch reactors to verify if the surfactant decreases the adsorption capacity of PWB with respect to toluene. The amount of adsorbed contaminant (mg/g) has been reduced to an approximately 50% which confirmed the affinity between surfactant and toluene. Secondly, the test has been run also in column, to simulate secondary source of contamination. The fixed bed column was filled with inert sand mixed with PWB (4% w/w) and saturated with 10 mg/L of toluene. After achieving equilibrium conditions (when the concentration of toluene in the outlet was equal to the inlet), the column has been flushed first with distillated water and then with surfactant. The results for the first investigated surfactant demonstrate that it has a high efficiency to increase mobility of contaminant. Experiments on another surfactant is ongoing.
2019
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1435809
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