Photo-assisted Fenton Reaction Research Articles

BioTemplated Fe3+-Doped g-C3N4 Heterojunction Micromotors for the Degradation of Tetracycline through the Photo-Fenton Reaction

The excessive discharge of antibiotics into aquatic systems is a major issue in many countries worldwide and poses a threat to human health and the sustainable development of society. Hence, developing efficient treatment methods and purification technologies to degrade antibiotics is essential. Herein, we present the synthesis of low-cost, self-propelled tubular Fe3+-incorporated graphitic carbon nitride (g-C3N4-Fe@KF) micromotors using kapok fibers (KFs) as templates and their application as photo-catalysts for the photo-Fenton degradation of tetracycline (TC) under visible-light irradiation. The g-C3N4-Fe@KF micromotors moved rapidly when being propelled by oxygen bubbles generated in a hydrogen peroxide (H2O2) solution as a result of a photo-assisted Fenton reaction. The motion behavior of the g-C3N4-Fe@KF micromotors was dependent on the concentration of H2O2 and the length of the micromotors. The propulsion mechanism was discussed in detail. The micromotors efficiently degraded antibiotics via the photo-Fenton process. Photo-Fenton degradation efficiency was attributed to the synergistic effects of the doped Fe3+ and g-C3N4 under visible-light irradiation and self-propulsion of the micromotors. In addition, the micromotors possessed good reusability, thereby efficiently realizing multiple cycles of degradation. The current work offers an avenue for the design of micromotors, using inexpensive approaches, for various potential environmental applications.

A short-circuited photo-assisted electrochemical cell for wastewater treatment

An economically attractive and highly efficient electrochemical cell is fabricated by connecting a carbon felt (CF) and a steel plate (S). Using this configuration, a photo-stimulated (CF/S) arrangement promotes photo-assisted Fenton reactions that result in the degradation of recalcitrant pollutants in water. As opposed to electro-Fenton reports that describe systems with externally polarized electrodes or photo-Fenton systems that utilize iron modified carbon substrates, this work proposes a short-circuited CF/S arrangement that does not require an external potential source. By following the color removal of a dye solution and the chromatography analysis of an emergent contaminant (sulfamethoxazole (SMX)), it was found that the highest efficiencies for the production of oxidative species are observed for tests performed under O2 saturation and UV light irradiation. Under these conditions, the CF/S arrangement achieves 97 % degradation of SMX (after 60 min) and 40 % of total organic carbon (TOC) removal after 240 min. Interestingly however, the CF/S arrangement also revealed a notable efficiency when anoxic and dark conditions were employed. We postulate that in this case, •OH radicals are produced by means of Fenton-like reactions and in order to support this interpretation, cyclic voltammetry and scanning electronic microscopy (SEM) and X-ray diffraction spectroscopy (XRD) measurements were carried out. The resulting data confirmed a Fenton-like mechanism that was further supported by the detection of •OH radical species that was assessed using coumarin absorption data. This study demonstrates that the CF/S cell is a promising approach for a novel photo-assisted Fenton wastewater treatment.

Enhanced 4-FP removal with MnFe2O4 catalysts under dielectric barrier discharge plasma: Economical synthesis, catalytic performance and degradation mechanism

The dielectric barrier discharge plasma (DBDP) process has received extensive attention for the removal of organic contaminants from water. A novel microwave-assisted hydrothermal method was used to easily and rapidly synthesize MnFe2O4 catalysts. Based on the DBDP process, MnFe2O4 can enhance 4-fluorophenol (4-FP) abatement from 44.15% to 58.78% through the catalysis within 18 min. Then, the adjunction of O3 generated by discharge can further boost 4-FP degradation to 94.94%. After the whole optimization process is complete, the associated pseudo-first-order reaction kinetic constant and energy efficiency were enhanced from 0.0327 to 0.1536 min−1 and 2067.13 mg kW h−1 to 4444.75 mg kW h−1, respectively. With the help of the condition, blank and radical capture experiments, the catalytic performance caused by MnFe2O4 and O3 was attributed to the joint action of Fenton-like reactions, photocatalysis (ultraviolet, UV), photoassisted Fenton reactions and O3 catalysis. The overall downward trend of the possible intermediate toxicities indicated that the DBDP/MnFe2O4/O3 process can effectively remove and mineralize 4-FP without the generation of more toxic intermediates. In addition, during the 5 cycles, MnFe2O4 can maintain excellent recovery, efficiency and durability. In summary, the coupling of discharge plasma and MnFe2O4 sheds new light on catalysis for wastewater treatment.

Photo-assisted Fenton reactions and growth evolution of crack-urchined CuBi2O4 microspheres assembled by nanorods

Hierarchical CuBi2O4 microspheres assembled by nanorods were prepared via a facile hydrothermal process. The nanorods were orderly grown along [001] crystal direction with rectangular cross-sections and a broad diameter distribution ranging of 100–350 nm. One narrow crack is distinct on the surfaces of each microsphere, which separates the microsphere into two approximately equal parts. Growth evolutions of as-prepared CuBi2O4 were fully discussed according to various reaction times. The microspheres were formed by radiated extension of nanorods which split along cleavage planes due to high internal stresses. The as-prepared CuBi2O4 exhibited a strong optical absorption in wavelength of 300–630 nm. Under visible light (λ ≥ 420 nm), an improved degradation efficiency of 89.6% to Rhodamine B (RhB) was determined with the aid of H2O2. The crack-urchined structures as well as the redox reactions between CuBi2O4 and H2O2 should be responsible for it.

Carbon nanodot-modified FeOCl for photo-assisted Fenton reaction featuring synergistic in-situ H2O2 production and activation

Achieving efficient production and activation of H2O2 is a promising strategy to enhance the efficiency of heterogeneous Fenton reactions. For this purpose, an ideal heterogeneous Fenton platform was constructed though chemical embedding of carbon nanodots (CDots) onto the surface of iron oxychloride (FeOCl/CDots). Experimental results and theoretical calculations confirmed that CDots acted as the reactive sites for highly effective separation of photogenerated electrons and holes in the FeOCl substrate, whereby the O2 molecules in solution could be synchronously reduced to H2O2 via a two-electron pathway (O2 → O2H → H2O2) on the CDots. Under visible light irradiation, the concentration of H2O2 accumulated to ∼337.2 μmol L−1 in the FeOCl/CDots system, which was almost ∼14 times higher than that using FeOCl alone. Moreover, the FeOCl substrate with abundant Fe2+ could directly capture and activate the H2O2 to produce abundant hydroxyl radical (OH), thereby effectively avoiding the H2O2 mass transfer limitation encountered in traditional heterogeneous Fenton reactions. In experiments with a typical organic contaminant (p-chlorophenol), the oxidation rate and mineralization efficiency in this Fenton system were ∼4 and ∼6 times higher than that achieved using FeOCl alone.

Degradation of methyl orange by photo assisted fenton reaction using Indonesian bauxite as catalyst

Photo fenton catalyst is an effective and environmentally friendly catalyst for degrade organic pollutants. Novel photo fenton catalyst was successfully prepared from Indonesia bauxite was used as a catalyst for degradation of methyl orange solution. This catalyst is more cheaper than Nafion-based catalyst and more greener than other synthesized catalysts. It is easily prepared from Indonesian natural resources. X-ray diffraction measurements provide structure and mineral composition of bauxite, while XRF provides information on the composition of Fe by 18% by weight of bauxite mass. The presence of large amounts of Fe in bauxite acts as a catalyst in the decomposition of metyl orange. Testing of photo fenton activity to decompose metyl orange showed that Indonesian bauxite had high catalytic activity, was able to decompose 99.4% metyl orange within 40 minutes on irradiation using an 9Watt UVC radiation source.

Impact of photocatalyst optical properties on the efficiency of solar photocatalytic reactors rationalized by the concepts of initial rate of photon absorption (IRPA) dimensionless boundary layer of photon absorption and apparent optical thickness

The concepts of “initial rate of photon absorption” (IRPA), “dimensionless boundary layer of photon absorption” and “apparent optical thickness (τapp)” are presented to evaluate the radiative transfer phenomena in solar, slurry, planar, photocatalytic reactors. The radiation field produced by suspensions of TiO2 and goethite, two photocatalysts with profoundly different optical properties used in heterogenous photocatalysis and heterogeneous photo-assisted Fenton reactions, was determined by the six-flux radiation absorption-scattering model coupled to the Henyey-Greenstein scattering phase function (SFM-HG). The concept of IRPA, defined by the differentiation at the local volumetric rate of photon absorption (LVRPA) at the reactor window boundary, is proposed as a new approach to determine the impact of catalyst loading and optical properties on the extinction of light inside a photoreactor. The IRPA showed that the extinction of light follows a second order dependency on the photocatalyst concentration while the impact of the optical properties can be expressed by a decoupled function (Ψ function). The Ψ function increased with photocatalyst concentration and approached a maximum at the same optimal photocatalyst concentration determined from the analysis of the total rate of photon absorption (TRPA) in the reactor. The analysis of TRPA and boundary layer of photon absorption redefined here in dimensionless form, as a function of τapp, determined that the most efficient rate of radiation absorption in solar powered planar reactors occurs at τapp = 4.1–4.4, with approximately 10% of the reactor width under darkness. τapp is a similarity dimensionless parameter exclusively derived from the SFM approach, which clusters the effects of photocatalyst loading, reactor dimension and photocatalyst optical properties, providing an ideal parameter for designing and scaling photocatalytic reactors operated with any kind of photocatalytic material.

Fenton-Reaction-Derived Fe/N-Doped Graphene with Encapsulated Fe3C Nanoparticles for Efficient Photo-Fenton Catalysis

An excellent Fenton catalyst requires high activity, good stability and also convenience in separation for recycling. In this work we report Fenton-reaction-derived iron/nitrogen-doped graphene with encapsulated iron carbide nanoparticles (Fe3C@Fe/N-G) as an excellent heterogeneous Fenton catalyst. It was synthesized via Fe3+/H2O2-Fenton-reaction-driven oxidative polymerization of dopamine on graphene oxide surface, followed by carbonization process. Detailed characterizations unveil that as-prepared Fe3C@Fe/N-G is made up of Fe/N-doped graphene sheets with encapsulated dense and homogeneous Fe3C nanoparticles. Due to its unique microstructure and rationally-combined components, this catalyst exhibits appealing catalytic performance including high activity and excellent recoverability in photo-assisted Fenton reaction. This work may offer a valuable route to rational design and controllable synthesis of high-performance transition metal-based catalysts.

Iron oxide nanoparticles supported on diamond nanoparticles as efficient and stable catalyst for the visible light assisted Fenton reaction

Iron oxide nanoparticles (Feox NPs) have been supported on the hydroxylated surface of modified diamond nanoparticles (D3). Characterization data show that, once formed, Fe NPs are spontaneously oxidized under ambient conditions, exhibiting a good dispersion of small oxidized Feox NPs (2.2 ± 0.5 nm) on D3. It has been observed that the activity of Feox/D3 as heterogeneous Fenton catalyst for phenol degradation by H2O2 can be assisted by visible light irradiation. Feox/D3 exhibits a superior activity compared with analogous catalysts based on activated carbon, graphite or the benchmark Feox/TiO2 photocatalyst. Feox/D3 exhibits comparable activity to Ag/D3 that is one of the most active catalysts ever reported for this reaction. In addition, Feox/D3 presents higher stability and recyclability than analogous Cu/D3. A minimum accumulated turnover number of 38,000 can be achieved using Feox/D3 as photocatalyst. The heterogeneous photoFenton process using phenol as model pollutant and Feox/D3 as catalyst under visible light irradiation can be implemented prior to an aerobic biological treatment resulting in a biodegradable effluent which lacks ecotoxicity, as determined by measurement of the biological oxygen demand. Transient absorption spectroscopy provides evidence in support of the formation upon irradiation of Feox/D3 of photogenerated charge separation state attributed to electrons and holes. Electron paramagnetic resonance and selective quenching experiments indicate that hydroxyl radicals are the main reactive oxygen species generated in the photo-assisted Fenton reaction promoted by Feox/D3.

Photocatalytic inactivation of highly resistant microorganisms in water: A kinetic approach

Abstract The mechanism for the photocatalytic inactivation of highly resistant microorganisms (i.e., Bacillus subtilis spores) in water was studied using a kinetic approach. This required characterizing the basic processes that occur within the photoreactor. The radiative intensity that entered the photocatalytic system was estimated using the ferrioxalate actinometrical process, the amount of hydroxyl radical produced under a specific photo-assisted Fenton reaction was measured, and a kinetic model to predict the hydroxyl radical generation was proposed to fit the experimental values. These results were then used to suggest new assessment related to the spore inactivation mechanism under controlled photo Fenton reaction conditions. The kinetic model was found to fit the experimental data fairly well (r2 > 0.99) and hydroxyl radical generation was determined to significantly affect the inactivation process. It was determined that a specific amount of hydroxyl radical is required to overwhelm the self-repairing mechanisms of the cell and cause cell death. The amount of hydroxyl radicals generated was found to be a function of radiative intensity and reagent concentration, as previously reported. The proposed relationship between the amount of hydroxyl radical and the inactivation process was supported by adding chloride ions to acting as radical scavengers. It was observed that even the lowest chloride ion concentration was capable of producing a significant delay in the inactivation process by scavenging hydroxyl radicals and generating low reactive species at the pH conditions tested.

Landfill Leachate Treatment Using Coupled, Sequential Coagulation-flocculation and Advanced Oxidation Processes

This study evaluated the efficiency of Fenton (Fe/H2O2) and photo-assisted Fenton (Fe2+/H2O2/UV) reactions combined with coagulation-flocculation (C-F) processes to remove the chemical oxygen demand (COD) in a landfill leachate from Mexico at a laboratory scale. The C-F experiments were carried out in jar test equipment using different FeSO4 concentrations (0.0, 0.6, 1.0, 3, and 6 mM) at pH = 3.0. The effluent from the C-F processes were then treated using the Fenton reaction. The experiments were carried out in a 500 mL glass reactor fillet with 250 mL of landfill leachate. Different molar ratio concentrations (Fe/H2O2) were tested (e.g., 1.6, 3.3, 30, 40 and 75), and the reaction was followed until COD analysis showed no significant further variation in concentration or until 90 min of reaction time were completed. The photo-assisted Fenton reaction was carried out using a UV lamp (365 nm, 5 mW) with the same Fe/H2O2 molar ratio values described above. The results suggested that the photo-assisted Fenton process is the most efficient oxidation method for removing organic matter and color in the leachate. The photo-assisted Fenton process removed 68% of the COD and 90% of the color at pH = 3 over 30 minutes of reaction time using a H2O2/Fe molar ratio equal to 75 only using a third of the reaction time of the previous process.

Study of the Influence of the Operational Parameters on the Photo-Electro-Fenton Performance of an Industrial Waste-Water Treatment Prototype

A design of experiments (DOE) was used to characterize the influence of the operational parameters of an industrial prototype for waste-water treatment that was designed and built to operate using the Photo-Electro-Fenton technology. Since the approach under study is based on the photo-assisted Fenton reaction, which in turn is based on the production of hydroxyl radical species via electro-generated hydrogen peroxide (H2O2) and iron ions (Fe2+), the reaction was carried out in a prototype conceived in two reactor chambers. While in the first chamber hydrogen peroxide (H2O2) is produced via oxygen reduction using carbon cloth electrodes, the aqueous solution passes to a second chamber containing an iron-loaded resin in which a UV lamp promotes not only the oxidant species production but also iron reduction. The performance of the industrial prototype was followed by the absorbance decrease of a commercial dye aqueous solution ( (4-(2-Hydroxy-1-naphthylazo) benzene sulfonic acid, sodium salt, ≥98.0%) considering the applied current, the amount of iron-loaded resin, the flow rate and the pH as the operational variables to be characterized and eventually optimized for the operation of the prototype. In this way, a 24 factorial design was considered with two levels for each variable, central points and duplicate and randomized experiments. Variable interactions from the DOE were assessed using variance analysis and parameter estimation (ANOVA) using the statistical software JMP 7.0.2, SAS Institute Incorporated. The results revealed that the interactions for which the Prob >ltl being 0.05 or less are those corresponding to pH, resin and the pH-current-resin interaction parameters. From this information and the corresponding analysis it was possible to obtain an empirical equation that describes the reactor´s performance, along with a series of surface response curves that provide information on the relationship of the different operational variables that control the generation of oxidant species and the performance of the prototype under study.

Removal of atrazine from water using an iron photo catalyst supported on activated carbon

Atrazine is a systemic triazine herbicide, which has been classified as an endocrine disrupting pesticide of hormones and the reproductive systems of humans. Moreover, atrazine was recently considered as a potential carcinogen by several reports. The aim of this work was to synthesize and to evaluate an iron catalyst supported on activated carbon to remove atrazine from water. Five different treatment schemas were evaluated: (1) adsorption with the photocatalyst’s support alone, (2) adsorption with the supported photocatalyst alone, (3) adsorption coupled to heterogeneous Fenton reaction, (4) adsorption coupled to heterogeneous advanced oxidation with UV light and (5) adsorption coupled to heterogeneous photo assisted Fenton reaction. The photocatalyst synthesized, via the incipient wet impregnation method, showed 1176 ± 24 m2/g of Langmuir area and 1.6 % wt/wt of iron content. After 120 min of reaction time, total removal efficiencies in the treatment schemas using the photocatalyst ranged from 70 % (mainly adsorption with the photocatalyst alone) to 96 % (Adsorption and heterogeneous photo assisted Fenton reaction). The heterogeneous photo assisted Fenton reaction was the fastest and most efficient treatment schema, with results better than that reported for similar materials. The adsorption data was fitted to a kinetic model of pseudo-second order and the results of advanced oxidation process were fitted to a kinetic model of fractional order.

Chloramphenicol Degradation in Fenton and Photo-Fenton: Formation of Fe2+-Chloramphenicol Chelate and Reaction Pathways

The aim of the present study was to investigate the formation of the Fe2+-chloramphenicol complex (FeCHPLCOM) and to compare the performances of Fenton processes for the degradation of CHPL and the FeCHPLCOM mixture at high concentration. LC-MS spectra evidenced for formation of charge transfer FeCHPLCOM at a 1:1 CHPL-to-Fe2+ ratio. CHPL acted as a bidented ligand coordinated with Fe2+. The IR study uncovered that ligand-to-metal bonding weakened the stretching frequency of both the O–H bond and the −C═O group through coordination with Fe2+. The enhanced FeCHPLCOM degradation (13.4% more) was found in a photoassisted Fenton reaction. The asymmetry centers of CHPL with weakly bonded hydrogen atoms of high nucleophilic character were the most preferred sites of HO• attack. CHPL was oxidized through segmentation of the aliphatic chain attached to the benzene ring under acidic conditions (pH 3). The toxicity of CHPL to Escherichia coli (E. coli) XL 10GOLD decreased significantly after 45 min of decomposition.

An Ru(II)-Fe(III) bimetallic complex as a multifunctional device for detecting, signal amplifying, and degrading oxalate.

A tetranuclear bimetallic complex, [Ru(II)((t)Bubpy)(CN)4]2-[Fe(III)(H2O)3Cl]2·8H2O (1) has been synthesized and characterized. It was found to be a multifunctional device that can detect, signal amplify, and degrade an organic pollutant, oxalate. Results of the chemosensing studies of 1 toward common anions show that only oxalate selectively induces naked-eye colorimetric and luminometric responses with method detection limits down to 78.7 and 5.5 ppm, respectively from 1. Meanwhile, results of the photo-degradation studies of 1 toward oxalate show that the dissolved organic carbon content of oxalate decreased and reached complete mineralization into CO2 within 6 hours. Complex 1 was also found as the catalyst that amplified the detection signal toward oxalate. Through the photoassisted Fenton reaction by 1, methyl orange, an additional coloring agent, could be degraded so that the visual detection limit of 1 toward oxalate was magnified 50 times from 100 to 2 ppm. The detection, degradation, mineralization and signal amplification were found applicable in real water bodies such as river, pond and underground water with excellent recoveries and relative standard deviation.

Degradation of Reactive Red K-2G by a Photoassisted Fenton Reaction Using a Novel Loading Phthalocyanine Sulfonic Iron Fibers as a Catalyst

Reactive dyes have been widely used in the dyeing of bright colourful silk fabrics. The discoloration and degradation of Reactive Red K-2G in waste water were discussed in this paper. A new heterogeneous photocatalyst named loading phthalocyanine sulfonic iron fibers (FePcS-F) was prepared by phthalocyanine sulfonic Iron supported by modified cellulose fibers in acidic condition. The photocatalytic degradation of Reactive Red K-2G was characterized by discoloration rate to evaluate the effect of catalyst dosage, catalyst loading (CFePcS-F) and solution pH. The results proved that increasing catalyst dosage and CFePcS-F significantly accelerated the dye degradation. FePcS-F catalyst showed higher photocatalytic activity when the solution’s pH value is equal to or less than 6.0, compared to alkaline medium.

Photoassisted Fenton Degradation of Polystyrene

Fenton and photoassisted Fenton degradation of ordinary hydrophobic cross-linked polystyrene microspheres and sulfonated polystyrene beads (DOWEX 50WX8) have been attempted. While the Fenton process was not able to degrade these polystyrene materials, photoassisted Fenton reaction (mediated by broad-band UV irradiation from a 250 W Hg(Xe) light source) was found to be efficient in mineralizing cross-linked sulfonated polystyrene materials. The optimal loadings of the Fe(III) catalyst and the H(2)O(2) oxidant for such a photoassisted Fenton degradation were found to be 42 μmol-Fe(III) and 14.1 mmol-H(2)O(2) per gram of the sulfonated polystyrene material. The initial pH for the degradation was set at pH 2.0. This photoassisted Fenton degradation process was also able to mineralize commonly encountered polystyrene wastes. After a simple sulfonation pretreatment, a mineralization efficiency of >99% (by net polymer weight) was achieved within 250 min. The mechanism of this advanced oxidative degradation process was investigated. Sulfonate groups introduced to the surface of the treated polystyrene polymer chains were capable of rapidly binding the cationic Fe(III) catalyst, probably via a cation-exchange mechanism. Such a sorption of the photoassisted Fenton catalyst was crucial to the heterogeneous degradation process.

Oxidation of two organophosphorous insecticides by the photo-assisted Fenton reaction

The photocatalytic degradation of two selected insecticides (dimethoate and methyl parathion) has been studied using the photo-assisted Fenton reaction. The degradation kinetics were studied under different conditions such as iron's and oxidant's concentration, temperature and inorganic ions. The degradation rates proved to be strongly influenced by these parameters. The replacement of hydrogen peroxide with peroxydisulfate was also tested in a photo-Fenton-like reaction. This system achieved high degradation rates of the selected compounds. Intermediate products formed during photocatalytic treatment were identified by means of solid-phase extraction (SPE) coupled to gas chromatography–mass spectroscopy techniques (GC–MS). Eight possible by-products were identified for parathion methyl and three for dimethoate formed through mainly oxidation and dealkylation reactions. Mineralization studies showed also that the photo-Fenton and the photo-Fenton-like systems are able to achieve mineralization of the insecticides. However, complete detoxification is achieved only in the presence of the photo-Fenton reagent.

UV-Fenton discolouration and mineralization of Orange II over hydroxyl-Fe-pillared bentonite

An efficient solid catalyst, hydroxyl-Fe-pillared bentonite (H-Fe-P-B), was successfully developed for photo-assisted Fenton reaction. The characteristics of the catalyst were detected by N 2 adsorption/desorption, X-ray fluorescence spectroscopy (XRF), X-ray powder diffraction (XRD), UV–vis absorption spectra (UV–vis) and atom force microscopy (AFM). The catalytic activity of H-Fe-P-B was evaluated in discolouration and mineralization of Orange II in UV-Fenton system. The effects of pH, Orange II concentration, UV light wavelength and temperature on Orange II degradation were studied in detail. It was found that the catalytic activity of H-Fe-P-B for H 2O 2 came from Fe-polycations between bentonite sheets rather than Fe 3+ or Fe 2+ in tetrahedral or octahedral sheets of bentonite. As the leaching of iron from the H-Fe-P-B after treatment was negligible, the H-Fe-P-B exhibited a high catalytic activity and good long-term stability in multiple runs in the discolouration and mineralization of Orange II. Because of the strong surface acidity, the H-Fe-P-B acted as not only catalyst but also solid acid in UV-Fenton system, as a result, almost 100% colour removal and 95% TOC removal of 0.2 mM Orange II could be obtained at 40 and 120 min even if the initial pH of solution was as high as 9.0. These results implied that the H-Fe-P-B was a promising catalyst for UV-Fenton system.

Degradation of 2,4‐Dichlorophenol by Combining Photo‐Assisted Fenton Reaction and Biological Treatment

The photo-Fenton reaction effect on the biodegradability improvement of 100 mg/L solution of 2,4-dichlorophenol (DCP) has been investigated. Biochemical oxygen demand (BOD) at 5 and 21 days, BODn/ chemical oxygen demand (COD) and BODn/total organic carbon (TOC) ratios, average oxidation state, and inhibition on activated sludge were monitored. For 50 mg/L hydrogen peroxide and 10 mg/L iron(II) initial concentrations and 40 minutes of reaction time in the photo-Fenton process, the biodegradability of the pretreated solution, measured as BOD5/COD ratio, was improved from 0 for the original DCP solution up to 0.18 (BOD21/COD = 0.24). At that point, all DCP was eliminated from the solution. To study the effect of the pretreatment step, the biological oxidation of pretreated solutions was tested in two semicontinuous stirred tank reactors, one operated with activated sludge and one with biomass acclimated to phenol. Results showed that more than 80% TOC removal could be obtained by codigestion of the pretreated solution with municipal wastewater. Total organic carbon removals of approximately 60% were also obtained when the sole carbon source for the aerobic reactors was the pretreated solution. The hydraulic retention times used in the bioreactors were of the same order of magnitude as those used at domestic wastewater treatment plants (i.e., between 12 and 24 hours). Kinetic studies based on pseudo-first-order kinetics have also been carried out. Constants were found to be in range 0.67 to 1.7 L x g total volatiles suspended solids(-1) x h(-1).