Influence of solubilizing agents (cyclodextrin or surfactant) on phenanthrene degradation by electro-Fenton process - Study of soil washing recycling possibilities and environmental impact

Abstract : One of the aims in soil washing treatment is to reuse the extracting agent and to remove the pollutant in the meantime. Thus, electro-Fenton (EF) degradation of synthetic soil washing solutions heavily loaded with phenanthrene was suggested for the first time. Two solubilising agents hydroxypropyl-beta-cyclodextrin (HPCD) and Tween 80(®) (TW 80) were chosen as cyclodextrin (CD) and surfactant representatives, respectively. In order to reuse HPCD and to degrade the pollutant simultaneously, the following optimal parameters were determined: [Fe(2+)] = 0.05 mM (catalyst), I = 2000 mA, and natural solution pH (around 6), without any adjustment. Only 50% of TW 80 (still higher than the critical micelle concentration (CMC)) can be reused against 90% in the case of HPCD while phenanthrene is completely degraded in the meantime, after only 180 min of treatment. This can be explained by the ternary complex formation (Fe(2+)-HPCD-organic pollutant) (equilibrium constant K = 56 mM(-1)) that allows OH to directly degrade the contaminant. This confirms that Fe(2+) plays an important role as a catalyst since it can promote formation of hydroxyl radicals near the pollutant and minimize HPCD degradation. After 2 h of treatment, HPCD/phenanthrene solution got better biodegradability (BOD5/COD = 0.1) and lower toxicity (80% inhibition of luminescence of Vibrio fischeri bacteria) than TW 80/phenanthrene (BOD5/COD = 0.08; 99% inhibition of V. fischeri bacteria). According to these data, HPCD employed in this integrated (soil washing + EF degradation) approach gave promising results in order to be reused whereas the pollutant is degraded in the meanwhile.
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https://hal.univ-lorraine.fr/hal-01413717
Contributor : Emmanuel Mousset <>
Submitted on : Saturday, December 10, 2016 - 7:32:13 PM
Last modification on : Tuesday, July 9, 2019 - 3:10:35 PM

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Emmanuel Mousset, Nihal Oturan, Eric D. van Hullebusch, Gilles Guibaud, Giovanni Esposito, et al.. Influence of solubilizing agents (cyclodextrin or surfactant) on phenanthrene degradation by electro-Fenton process - Study of soil washing recycling possibilities and environmental impact. Water Research, IWA Publishing, 2014, 48, pp.306-316. ⟨hal-01413717⟩

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