Biodegradable Polyoxyethylenated Pentaerythritol Quaternary Esters as Oil Spill Dispersants

Abstract

Abstract Four polyoxyethylenated pentaerythritol (PE) ester surfactants have been synthesized. The molecular weights of these surfactants were calculated and evaluated experimentally by GPC and confirmed by calculations based on 1H-NMR. Also, their HLB values were calculated by Griffin formula. The surface tension and thermodynamic properties of the surfactants were obtained from surface tension measurements at different temperatures (298 – 318 K). It was found that the minimum area/surfactant molecule (Amin) for the investigated surfactants increased with increasing the molecular weight of the incorporated ethylene oxide. The thermodynamic parameters of micellization (ΔGmic, ΔHmic and ΔSmic) and that for adsorption (ΔGad, ΔHad and ΔSad) were also calculated. The more negative Gibbs free energy of adsorption values than those of micellization suggest that these surfactants favor adsorption than micellization. This finding is utilized for monitoring their dispersancy power. It was found that the water solubility of the prepared surfactants is correlated to their HLB values. Furthermore, the biodegradability of the prepared compounds was studied at different conditions in order to investigate their usability as oil spill dispersants. The data revealed that PE200-C12 had maximum dispersion efficiency and it was completely biodegraded after 8 days.