Amphoteric Surfactants for PAH and Lead Polluted-Soil Treatment Using Flotation

Abstract

Polluted soils are a problem of major concern impacting the health of the global environment and human beings. Without any safe technology for polluted soil treatment, most of the contaminated soils go to landfill especially when metals are the pollutants. This research compares the performance of non ionic (Brij 35 and Tween 80) and amphoteric (cocamydopropyl hydroxysultaine (CAS) and coamydopropylbetaine (BW)) surfactants for polycyclic aromatic hydrocarbons (PAHs) and metals (mainly Pb) removal from three contaminated soils. Best removal yields have been obtained using 0.5% (w/w) of CAS surfactant with 46 ± 2% for PAHs and 21 ± 5% for Pb simultaneously removed. Sodium chloride and EDTA have been shown to considerably enhance Pb solubilization (respectively 55 ± 5% and 35 ± 12% for [NaCl] = 5.5 M and [EDTA] = 0.025 M). Flotation technology has been tested as a separating technique of PAHs micelles and Pb from aqueous solution and has given good results for both contaminants (54 ± 7% for both PAH and Pb, using [CAS] = 0.5%, [NaCl] = 5.5 M, pH = 3). Finally, this study proposes a soil washing process using flotation to treat soil polluted with both organic and inorganic compounds. The suggested process concentrates the organic compounds in the froth and the inorganic pollutants in the liquid fraction.