Oxydation du phénanthrène dans les effluents de lavage des sols par des radicaux hydroxyle et sulfate photogénérés

Oxidation of phenanthrene in soil washing effluent by photogenerated hydroxyl and sulfate radicals

• Auteur / Autrice : Yufang Tao
• Direction : Gilles Mailhot
• Type : Thèse de doctorat
• Discipline(s) : Chimie Théorique, Physique, Analytique
• Date : Soutenance le 25/11/2020
• Etablissement(s) : Université Clermont Auvergne‎ (2017-2020)
• Ecole(s) doctorale(s) : École doctorale des sciences fondamentales (Clermont-Ferrand)
• Partenaire(s) de recherche : Laboratoire : Institut de Chimie de Clermont-Ferrand (Aubière, Puy-de-Dôme ; 2012-....)
• Jury : Président / Présidente : Vanessa Prévot
• Jury : Examinateurs / Examinatrices : Marcello Brigante, Hui Zhang
• Jury : Rapporteur / Rapporteuse : Zhihui Ai, Alessandra Bianco-Prevot

Mots clés

Mots clés contrôlés

Composés aromatiques polycycliques

Mots clés libres

Radical hydroxyle

Radical sulfate

Hydrocarbures aromatiques polycycliques

Effluent de lavage des sols

Procédé photo-Fenton

Hydroxyl radical

Sulfate radical

Polycyclic aromatic hydrocarbons (PAHs)

Soil washing effluent

Photo-Fenton process

Résumé

Résumé indisponible.

Soil contamination by toxic pollutants, especially by the recalcitrant hydrophobic organic compounds (HOCs) is a matter of significant public, scientific and regulatory concerns worldwide. Polycyclic aromatic hydrocarbons (PAHs) are typical representatives of HOCs being detected in the contaminated soil due to their ubiquitous occurrence, long-term persistence and low solubility in water. Surfactant-enhanced ex-situ soil washing (SW) has been proposed as a promising technology for elimination of PHE from contaminated soils due to its high extraction efficiency and low remediation cost. Nevertheless, the SW process generates a large amount of effluent containing soil pollutants and surfactant, which should be further treated with appropriate methods for the complete elimination of soil pollutants. In the past few decades, hydroxyl radical (HO•) or sulfate radical (SO4•−) based AOPs have been extensively investigated for the treatment of contaminants in water under UV irradiation. However, the investigation on PAHs decomposition in SW effluent by UV light-based AOPs is pretty limited. In this dissertation, the oxidation of the model PAHs compound phenanthrene (PHE) in surfactant Tween 80 (TW80) aided SW effluent has been investigated using HO• and/or SO4•− radicals produced in the photochemical processes. The decomposition efficiencies are evaluated, and the oxidation mechanism, the effect of co-existing species are elucidated. The main content and results consist of: (1) The degradation of PHE in mimic and real SW effluents using UVB light assisted activation of hydrogen peroxide (H2O2) and persulfate (PS) oxidation processes was investigated. The results revealed the oxidation efficiency was greatly impacted by oxidant concentration while the initial solution pH has little influence on PHE decomposition. The effect of inorganic anions (Cl−, HCO3− and NO3−) on the PHE degradation efficiency was evaluated under various experimental conditions. Chloride VII was found to play different roles in the two activation systems. The influence of bicarbonate in UVB/PS for PHE elimination was negligible, while an inhibition effect was observed for UVB/H2O2 system. Nitrate inhibited the PHE degradation in both UVB/H2O2 and UVB/PS processes. Application of the two activation processes on real SW effluents indicated that up to 85.0 % of PHE degradation could be reached under 6h UVB irradiation with PS. Finally，energy consumption in the two AOPs was compared and UVB/PS was suggested to be more cost-effective process than UVB/H2O2. (2) Fe(III)-CA was employed in the photo-Fenton processes to remove PHE from mimic SW solution. The introduction of Fe(III)-CA strongly intensified PHE oxidation when compared with photo-Fenton process using traditional iron ions, and Fe(III)-CA was more efficient than other Fe(III) organic complexes. PHE decay obey a two-stage profile and the oxidative degradation rates of the two stages and total removal efficiencies of PHE were mainly impacted by Fe(III)/CA ratio, Fe(III)-CA dosage, H2O2 concentration, and initial pH. According to the radical scavenging tests, HO• was the dominant active species though O2•− was also involved in the photo-Fenton process. (3) The oxidation of PHE in mimic SW effluent was performed by enhanced activation of PS using Fe(III)-EDDS complexes under simulated solar light irradiation. The presence of Fe(III)-EDDS pronouncedly enhanced PHE photo-oxidation with PS, and PHE kinetic showed two different decay steps. The influence of initial solution pH on PHE degradation could be neglected. The rise of PS concentration increased the oxidation efficiency of PHE while higher TW80 dosage exhibited stronger inhibition of PHE degradation. The concentration of Fe(III)-EDDS evidently affected PHE oxidation and the optimal concentration was 0.5 mM. The effect of chloride on PHE oxidation was evaluated and it was found that the presence of chloride significantly VIII enhanced PHE decomposition. (...)