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

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• 作者：Emmanuel Mousset ; Nihal Oturan ; Eric D. van Hullebusch ; Gilles Guibaud ; Giovanni Esposito ; Mehmet A. Oturan
• 关键词：PAHs ; HPCD ; Tween 80 ; Advanced oxidation processes ; Recycling ; Bioassays
• 刊名：Water Research
• 出版年：1 January, 2014
• 年：2014
• 卷：48
• 期：Complete
• 页码：306-316
• 全文大小：1088 K

文摘

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^庐 (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: [Fe²⁺]聽=聽0.05聽mM (catalyst), I聽=聽2000聽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聽min of treatment. This can be explained by the ternary complex formation (Fe²⁺-HPCD-organic pollutant) (equilibrium constant K聽=聽56聽mM^鈭?) that allows OH to directly degrade the contaminant. This confirms that Fe²⁺ plays an important role as a catalyst since it can promote formation of hydroxyl radicals near the pollutant and minimize HPCD degradation. After 2聽h of treatment, HPCD/phenanthrene solution got better biodegradability (BOD₅/COD聽=聽0.1) and lower toxicity (80% inhibition of luminescence of Vibrio fischeri bacteria) than TW 80/phenanthrene (BOD₅/COD聽=聽0.08; 99% inhibition of V. fischeri bacteria). According to these data, HPCD employed in this integrated (soil washing聽+聽EF degradation) approach gave promising results in order to be reused whereas the pollutant is degraded in the meanwhile.