Aqueous solutions of diethyl phthalate (DEP) were oxidized by using ozone combined with Fenton reagents. The effects of operating parameters such as initial pH; initial concentration of DEP, H₂O₂ and Fe²⁺; [H₂O₂]₀/[Fe²⁺]₀ ratio and O₃ dosage on the degradation rates of DEP were investigated. The results showed that DEP degradation is strongly dependant on the pH; initial concentrations of the phthalate, H₂O₂ and Fe²⁺; [H₂O₂]₀/[Fe²⁺]₀ ratio and O₃ dosage. The addition of H₂O₂ and Fe²⁺ ions was effective to achieve almost 98% degradation of 200 mg L⁻¹ of DEP in about 40 min using a dose of O₃ = 45 g m⁻³ NTP; [H₂O₂]₀ = 2.5 × 10⁻² mol L⁻¹ and [Fe(II)]₀ = 5 × 10⁻³ mol L⁻¹, as compared to over 60 min by using O₃ and Fenton processes applied separately. DEP degradation followed apparent pseudo-first-order kinetics under ozonation, Fenton's reagents oxidation and the combined ozonation/Fenton reagents oxidation process. The overall reaction rates were significantly enhanced in the O₃/Fe²⁺/H₂O₂ oxidation system, and allows achieving 100% degradation of DEP (100 mg L⁻¹) in 30 min of reaction time. The notable decrease in DEP removal rate observed in the presence of a radical scavenger indicates that there was an obvious synergetic effect in the combined ozonation/Fenton reagent process most likely because ozonation could accelerate Fenton reagents to generate hydroxyl radical HO•. Thus, the reaction between DEP and HO• proceeds mainly in the bulk of the aqueous phase. Under optimal conditions, the O₃/Fe²⁺/H₂O₂ system oxidation was the most effective in DEP removal in water.

Biological pre-treated landfill leachates of Djebel Chakir contains some macromolecular organic substances that are resistant to biological degradation. The aim of the present work is to assess the feasibility of removing refractory organic pollutants in biological pre-treated landfill leachate by solar photocatalyse process. Leachate pollutant contents are studied to assess their contribution to leachate pollution and their treatability by solar photocatalyse process. Phenol is chosen as model of pollutants, to evaluate its removal and the efficiency of the photocatalytic system. The experiments were carried out in suspended photocatalytic reactor, using TiO₂ Degussa P25, under sunlight illumination (UV-A: 15–31 W/cm²). Under optimum operational conditions, applied to single reactant (phenol), the system presents a TOC removal of 90% (the degradation follows a first-order kinetic). Based on the TOC removal, the results shows that the degradation of biological pre-treated leachate follows a zero-order kinetic. After 5 h of sunlight exposure, 74% of COT is removed. The TOC removal is the best without any correction of the pH and at the TiO₂ concentration of 2.5 g/L. The photocatalytic degradation of organic contaminants as well as the formation and disappearance of the by-products were followed by GC/MS. The solar photocatalysis processes induce several modifications of the matrix leading to more biodegradable forms: all the remaining and new compounds generated after the biological pre-treatment of leachate are degraded and other types of organics appear, mainly carboxylic acid, aliphatic hydrocarbons and phtalic acids.

Diethyl phthalate (DEP) is one of the phthalate esters having wide industrial applications, but its occurrence in the aquatic environment has been linked to disruption of the endocrine system. In this study, the removal of DEP with ozone alone (OA) and heterogeneous catalytic ozonation (HCO) with activated carbon (AC) was investigated. Results show that the addition of AC was effective to achieve almost 100% degradation of DEP in about 30 min using 2.86 g AC/L as compared to over 80 min without AC. It was also found that radical reactions were the main mechanism by which DEP was degraded and adsorption contributed significantly to the removal of DEP by OAC. Indeed, after 60 min, adsorption alone achieved about 75% removal, whilst OA achieved 92% removal. In contrast, as expected molecular ozone reactions were relatively insignificant. The contribution of adsorption and radical reactions to the overall removal of DEP were of similar rates at the beginning of the experiments but the latter declined due to competitive reactions. The notable decrease of DEP removal rate observed in the presence of radical scavenger tert-butanol (tb) indicates that the reaction between DEP and proceeds mainly in the bulk of the aqueous phase. Moreover, the experimental results also revealed that in the absence of tb and after 40 min, almost 100% removal was observed as compared to only 64% when tb was added to the solution. This confirms that radical reactions play an important role in DEP removal by the OAC process. A model taking into account the various reactions in the bulk solution and on the surface of AC was developed and was found to predict well the experimental data. This study proves that HCO was effective to remove DEP and the changes of the contributory mechanisms underpinning the process were determined as function of time.

Diethyl phthalate (DEP) has been classified as an endocrine disruptor pollutant. The degradation of DEP C₁₂H₁₄O₄, in aqueous solution by TiO₂-UV process was optimized using high pressure mercury lamp. Effects of TiO₂ dosage and type, and pH values on the degradation of DEP by TiO₂/UV process were investigated. The optimal TiO₂ dosage and pH value for the DEP degradation were 1 g l⁻¹ and 7.0, respectively using TiO₂ P25. The degradation rate of DEP by TiO₂/UV process under optimal conditions reach 78.6% and could be fitted first-order kinetics.