Heterogeneous photo-Fenton Process Research Articles

The behavior of surface acidity on photo-Fenton degradation of ciprofloxacin over sludge derived carbon: Performance and mechanism

Sludge derived carbon (SC) has been widely used in advanced oxidation processes as an effective and economic catalyst. In this study, we applied surface modified SC for the first time to catalyze the heterogeneous photo-Fenton process with ciprofloxacin, a highly concerned emerging contaminant, as a model substance. H2SO4 was used to acidify the SCs under varying acid dosages, temperatures, and reaction time lengths. The surface acidity of SCs was quantitatively characterized with NH3-TPD. A strong correlation between the surface acidity and the catalytic activity was clearly demonstrated. The highest catalytic activity was obtained with SC whose acidity was 0.149 mmol·g−1 after being modified with 6 mol·L−1 H2SO4 at −20 ℃ for 24 h. In addition, XRD, XRF, BET, XPS, and HRTEM were also used to characterize the obtained SC. ·OH radicals were found to be the main reactive species by EPR. Ten transformation products were identified by GC–MS, based on which three possible reaction pathways were proposed.

Fe3O4 hollow nanospheres on graphene oxide as an efficient heterogeneous photo-Fenton catalyst for the advanced treatment of biotreated papermaking effluent.

This study focused on the feasibility of using Fe3O4/graphene oxide (FGO) nanocomposites as heterogeneous catalysts for the advanced treatment of real industrial wastewater. FGO nanocomposites with different graphene oxide (GO) ratios were synthesized by coprecipitating iron salts onto GO sheets in basic solution. The characterization of the resulting material structures and functionalities was performed using a range of analytical techniques. A low GO loading afforded a good Fe3O4 nanoparticle dispersibility and resulted in a higher Brunauer-Emmett-Teller surface area and pore volume. The FGO nanocomposites and pure Fe3O4 were used to treat papermaking wastewater in a heterogeneous photo-Fenton process. The results suggested that the nanocomposite designated FGO1 (GO loading of 25 mg) exhibits a higher photocatalytic efficiency than other FGO nanocomposites and pure Fe3O4. A maximum chemical oxygen demand degradation efficiency of 89.6% was achieved in 80 min with 1.5 g L-1 FGO1 at pH 3. The degradation of different pollutants present in wastewater was evaluated with the aid of gas chromatography-mass spectrometry and 3D excitation-emission-matrix analysis. Inductively coupled plasma atomic emission spectroscopy and magnetic measurements confirmed that the FGO1 nanocomposites possess a low iron leachability and a high reusability. Thus, a comprehensive advanced treatment of real industrial wastewater using a magnetic FGO catalyst is demonstrated.

Nontronite mineral clay NAu-2 as support for hematite applied as catalyst for heterogeneous photo-Fenton processes

This study describes the characterization of Nontronite, a clay mineral with high content of structural iron, before and after iron incorporation and 600 °C heat treatment. The Nontronite was classified as a mesoporous material, with high absorption in the UV–Vis range and band gap energy of 1.9 eV, indicative of the presence of superficial hematite, also verified in XRD analysis. The heat treatment promoted a structure rearrangement and the conversion of other iron phases to hematite, allowing the formation of surface irregular sites on Nontronite and facilitating the access for the decomposition of H2O2 into HO. Its catalytic activity in heterogeneous photo-Fenton process was evaluated during the degradation of the antibiotic sulfathiazole (STZ) and showed high activity achieving undetectable levels of STZ after 20 min under UV-LED irradiation and solar irradiation, and showing no iron leaching under controlled pH = 3. The degradation intermediates identified indicated hydroxylation as the main degradation route.

Comparison of Advanced Oxidation Processes for the Degradation of Maprotiline in Water—Kinetics, Degradation Products and Potential Ecotoxicity

The impact of different oxidation processes on the maprotiline degradation pathways was investigated by liquid chromatography-high resolution mass spectrometry (LC/HRMS) experiments. The in-house SPIX software was used to process HRMS data allowing to ensure the potential singular species formed. Semiconductors photocatalysts, namely Fe-ZnO, Ce-ZnO and TiO2, proved to be more efficient than heterogeneous photo-Fenton processes in the presence of hydrogen peroxide and persulfate. No significant differences were observed in the degradation pathways in the presence of photocatalysis, while the SO4− mediated process promote the formation of different transformation products (TPs). Species resulting from ring-openings were observed with higher persistence in the presence of SO4−. In-silico tests on mutagenicity, developmental/reproductive toxicity, Fathead minnow LC50, D. magna LC50, fish acute LC50 were carried out to estimate the toxicity of the identified transformation products. Low toxicant properties were estimated for TPs resulting from hydroxylation onto bridge rather than onto aromatic rings, as well as those resulting from the ring-opening.

Degradation of anti-inflammatory drug diclofenac using cobalt ferrite as photocatalyst

Emerging pollutants, among them pharmaceutical compounds, are found in surface and ground waters, suggesting their ineffective removal by conventional wastewater treatment technologies. In this paper, the removal of sodium diclofenac, a widely used non-steroidal anti-inflammatory drug, was explored by a heterogeneous Photo-Fenton process using CoFe2O4, H2O2 and Uv germicide radiation (254nm). Cobalt ferrites, were obtained by Pechini method and calcined at 600°C and 800°C. They were characterized by X-ray diffraction, Uv visible spectroscopy, Mössbauer and X-ray photoelectron spectroscopy, temperature-programmed reduction and specific surface area. The inverse spinel structure was obtained, and both materials presented good performance in the photo-Fenton reaction. A degradation mechanism based on the generation of OH groups is suggested. The complete sodium diclofenac degradation and 86% of mineralization of the total organic carbon were obtained using cobalt ferrite calcined at 800°C. This catalyst was used in three cycles, without activity loss showing a negligible Fe leaching.

Exploring the influence of varying pH on structural, electro-optical, magnetic and photo-Fenton properties of mesoporous ZnFe2O4 nanocrystals.

An economically viable and superficial technique was indorsed to yield ZnFe2O4 nanocrystals in the system to investigate the impact of pH variation on the optical, structural, electrical, and magnetic properties of as-prepared nanocrystals. The as-synthesized ZnFe2O4 nanocrystals were premeditated with the application protracted to degradation of Methylene blue organic dye. The results specify that the pH plays the utmost decisive facet in photo-Fenton recital. From XRD (X-Ray diffraction) analyses, it was confirmed that as-synthesized nanocrystals belong to a cubic Fd3m crystal phase. The crystallite size was also determined by the Scherrer formula and it was noticed that as the pH rises the crystallite size also increased. FT-IR (Fourier Transform Infrared) analysis depicts two absorption peaks∼500 and ∼600cm-1 that represents tetrahedral (Td) and octahedral (Oh) sites. Using TEM (Transmission Electron Microscopy), the morphology was observed to be spherical particles with some agglomeration. Photoluminescence and UV-visible spectral studies were performed to investigate the optical properties. The bandgap energy was seen to decrease as the pH increased. Using BET analysis, the surface area for the as-synthesized samples was found to decrease on increasing the pH. The reaction results showed that the ZnFe2O4 has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe2O4 produced by the co-precipitation route exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 99.2% of decolorization at 100min. Therefore, ZnFe2O4 particles rapidly prepared by the co-precipitation route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. With the help of VSM analysis, the coercivity and other magnetic properties were determined for the as-synthesized nanocrystal with plays a significant role in photocatalytic recyclability, which intends to premediate that the prepared nanocrystals can be used in industrial persistence.

Magnetic field-enhanced radical intensity for accelerating norfloxacin degradation under FeCu/rGO photo-Fenton catalysis

• FeCu/rGO was facilely prepared via a one-step hydrothermal co-reduction process. • A strong synergistic effect between Fe and Cu species promoted NOR degradation. • Enhanced •OH and •O 2 – /•HO 2 were observed with an external magnetic field (200 mT). • The magnetic field further accelerated NOR removal (34.1%) and H 2 O 2 usage (27.0%). • The mechanism of magnetic field-improved FeCu/rGO photo-Fenton catalysis was proposed. Improving the efficiency of photo-induced carriers (e - /h + ) is one of the most effective routes to accelerate the heterogeneous photo-Fenton process. Herein, inspired by inverse Lorentz forces of opposite charges in a magnetic field, an external magnetic field intensified photo-Fenton catalysis for norfloxacin (NOR) degradation was constructed under visible light irradiation. The reduced graphene oxide-supported Fe-Cu bimetal (FeCu/rGO), obtained by employing common iron powder as a reducing agent, was served as a model catalyst. Impressively, the intensities of both carriers and radicals (•OH and •O 2 – /•HO 2 ) were increased after the normal photo-Fenton reactor was placed into two fixed permanent magnets (200 mT), leading to a 34.1% improvement in NOR removal. Meanwhile, the consumption of H 2 O 2 was also critically boosted (from 65.1% to 92.1%). Combined with theoretical studies, the enhanced radicals were not only resulted from accelerated carrier separation but also extended O-O and O–H bonds in H 2 O 2 and facilitated spin evolutions of 1 [HO•↑···↓•OH] → 3 [HO•↑···↑•OH] and 1 [HOO•↑···↓•H] → 3 [HOO•↑···↑•H]. This study offers an insight into the specific role of an external magnetic field in promoting heterogeneous photo-Fenton catalysis.

Utilization of iron sludge resulted from electro-coagulation in heterogeneous photo-Fenton process

Abstract The iron sludge generated from an electrocoagulation process was employed for the degradation of phenol through photo-Fenton process instead of iron salts. The morphology, functional groups and chemical composition of the iron sludge were investigated using scanning electron microscopy, Fourier infrared spectroscopy, and energy-dispersive X-ray spectroscopy. The effects of iron dose, H2O2 concentration, reaction time and initial concentration of phenol on photo-Fenton process performance were studied. The degradation efficiency of phenol reached 100% in the case of light compared to 68.6% in the case of dark reaction at pH of 3, iron dose of 150 mg/L and H2O2 concentration of 1.5 g/L. The degradation efficiencies of phenol were 100%, 71.3 and 51% at initial phenol concentrations of 50 mg/L, 100 mg/L and 150 mg/L, respectively. The expected cost for the treatment of one cubic meter of the contaminated wastewater was estimated to be 0.6224 $/m3.

Fabrication of poly(vinyl alcohol)/sodium alginate hydrogel beads and its application in photo-Fenton degradation of tetracycline

Developing a reusable and durable catalyst for heterogeneous photo-Fenton process is of great importance for the practical application in the environment remediation. In this study, poly(vinyl alcohol) (PVA)/sodium alginate (SA) hydrogel beads were constructed using FeCl3 and boric acid as cross-linking agents. Characterizations and tests were employed to investigate the structure, optical property and durability of the obtained beads. The photo-Fenton performance of the PVA/SA-FeCl3 beads was evaluated by degradation of tetracycline (TC) under visible-light irradiation. The results show that the constructed beads exhibit porous structure, display a broad absorption band in the visible region and behave excellent stability against mechanic effects. The photocatalytic experiment result indicates that the removal rate of TC reaches 90.5% under optimized conditions, while the removal rate of total organic carbon reaches 28.6%. By analyzing the degradation of TC after adding active species scavengers, a photocatalytic mechanism was proposed. Moreover, PVA/SA-6% FeCl3 beads could be easily separated and recycled in water purification. This work provides a facile and robust method to construct reusable and durable Fe(III)-containing hydrogel beads with acceptable photo-Fenton catalytic performance under visible-light irradiation, paving the way for its practical application in wastewater treatment.

Estudio de la actividad catalítica de la ferrita de cobalto en la degradación de diclofenac sódico

Los contaminantes emergentes y dentro de ellos los compuestos farmacéuticos suelen encontrarse en aguas superficiales y residuales a lo largo del planeta. En este trabajo se presenta el estudio de la degradación de diclofenac sódico mediante un proceso tipo foto-Fenton heterogéneo empleando ferritas de cobalto. Los materiales fueron sintetizados con el método de Pechini y caracterizados mediante difracción de rayos X, espectroscopía Mössbauer, espectroscopía fotoelectrónica de rayos X, espectroscopía Uv-visible, reducción a temperatura programada y área superficial. Se obtuvieron fases puras con estructura de espinela. Ambos materiales presentaron buenos resultados catalíticos en la degradación del contaminate. Se propone un mecanismo de reacción radicalario basado en la formación de radicales *OH. Se logró una degradación completa del compuesto, con un 86% de mineralización del carbono orgánico total empleando el material calcinado a 800°C. El catalizador presentó excelentes resultados en tres ciclos consecutivos de uso.

Adsorptive and photocatalytic activity of Fe3O4-functionalized multilayer graphene oxide in the treatment of industrial textile wastewater.

Multilayer graphene oxide (mGO) was synthesized and functionalized via co-precipitation method to produce magnetic Fe3O4-functionalized multilayer graphene oxide nanocomposite (MmGO). Photocatalytic properties of MmGO were investigated in the photodegradation of raw textile wastewater samples. Fourier-transformed infrared spectroscopy revealed Fe-O vibrations, characterized by the band shift from 636.27 to 587.25 cm-1 on MmGO. X-ray diffraction confirmed the successful oxidation of graphite by the (002) peak at 10° and indicated the presence of Fe3O4 on MmGO surface by the peaks at 2θ 35.8° (311), 42.71° (400), 54.09° (511), and 62.8° (440). There was no detection of coercivity field and remnant magnetization, evidencing a material with superparamagnetic properties. Then, the textile effluent was treated by heterogeneous photo-Fenton (HPF) reaction. A 22 factorial design was conducted to evaluate the effects of MmGO dosage and H2O2 concentration on HPF, with color and turbidity removal as response variables. The kinetic behavior of the adsorption and HPF processes was investigated separately, in which, the equilibrium was reached within 60 and 120 min, for adsorption and HPF, respectively. Pseudo-second-order model exhibited the best fit, with COD uptake capacity at equilibrium of 4094.94 mg g-1, for chemical oxygen demand. The modeling of kinetics data showed that the Chan and Chu model was the most representative for HPF, with initial removal rate of 95.52 min-1. The removal of organic matter was 76.36% greater than that reached by conventional treatment at textile mills. The presence of Fe3O4 nanoparticles attached to MmGO surface was responsible for the increase of electron mobility and the enhancement of its photocatalytic properties. Finally, MmGO presented low phytotoxic to Cucumis sativus L. with a RGI of 0.53. These results bring satisfactory perspectives regarding further employment, on large scale, of MmGO as nanocatalyst of textile pollutants.

Synthesis of mixed oxide Ti/Fe2O3 as solar light-induced photocatalyst for heterogeneous photo-Fenton like process

Ti/Fe2O3 (Ti/Fe mass ratio ∼ 0.22) magnetic catalysts were prepared by a modified Pechini method and evaluated for heterogeneous photo-Fenton-like process for degradation of Reactive Black 5 (RB5) textile dye under artificial solar light irradiation. Catalysts were calcined at temperatures of 500–700 °C, and were characterized by TGA, XRD, N2 adsorption/desorption, FTIR, SEM, EDX and UV/Vis DRS analyses. The photo-Fenton experiments were conducted at pH 2.5, H2O2 initial concentration of 12 mmol L−1 and 0.40 g L−1 of catalyst. Results showed that catalyst calcined at 500 °C (TiFeO-500) achieved 100 % degradation of textile dye, the highest photoactivity, when compared with the materials calcined at either 600 or 700 °C and to the pure oxides α−Fe2O3 or TiO2, under the same conditions. Kinetic data related to RB5 dye degradation with TiFeO-500 catalyst was well fitted to the pseudo-first order model with initial reaction rate of 0.28 mg L−1 min−1. The high catalytic activity of this material was favored by its multiple bandgap from UV to visible range, as well as to its nanometric particle size and low agglomeration. Photoreduction efficiency of the Fe3+ to Fe2+ was favored by the synergy with Ti4+ and possible amorphous Fe and Ti oxysulfate species in the photo-Fenton like process for the production of hydroxyl radical (•OH) and dye degradation.

Micropollutant degradation by the heterogeneous solar photo-Fenton process at circumneutral PH using copper slag

This work evaluates the catalytic capacity of a metallurgical copper slag (CS) for the removal of the pesticide Thiabendazole (TBZ) in real wastewater by the heterogeneous photo-Fenton process at circumneutral pH under natural solar irradiation (NSI). The material consists mainly of magnetite and fayalite. The best experimental condition was: 17 mg of CS/cm2, settled at the bottom of the reactor, and 0.44 mM H2O2 illuminated with solar radiation. Under this condition, 80% TBZ degradation (100 μg/L initial spiked concentration) was reached in real WWTP secondary effluent, after 120 min with 50% of H2O2 consumption. The CS-H2O2-NSI system produced 2-fold more hydroxyl radicals (HO•) with respect to the CS-H2O2. The CS-NSI system did not produce HO• radicals, probably due to the fast electron-hole combination reported for one of the iron oxides present in CS, even though it showed a bandgap value of 2.42 eV, which indicates that the material can absorb solar irradiation. Thus, TBZ was oxidized mainly through the heterogeneous photo-Fenton-like reaction, with similar degradation efficiencies after five utilization cycles. This study demonstrates that CS is a chemically stable and efficient Fenton type catalyst for microcontaminant degradation in wastewater.

Influence of Cr doping on the structural, magnetic, optical and photocatalytic properties of α-Fe2O3 nanorods

Pure and Cr-doped hematite (α-(Fe1-xCrx)2O3, x = 0, 0.026, 0.039, 0.085 or 0.135) nanorods were prepared by a simple co-precipitation and calcination method. Influence of different levels of Cr doping on the change of properties of long and thin pure hematite nanorods was investigated. Cr3+-for-Fe3+ substitution in the crystal structure of hematite was proved by measuring a gradual contraction of the unit cell and a gradual decrease of the hyperfine magnetic field by increasing the Cr molar fraction. Cr doping induced an increase in the width and thickness of hematite nanorods, as well as a decrease in the overall surface area. Low temperature 57Fe Mössbauer spectroscopy showed that the Morin transition in hematite was suppressed by Cr doping to temperatures below 80 K. Magnetic measurements confirmed the suppression of the Morin transition in Cr-doped hematite down to 5 K. Infrared spectra of Cr-doped hematite samples showed shifts of IR bands by Cr3+-for-Fe3+ substitution. Optical properties of α-Fe2O3 nanorods changed significantly by Cr doping – the absorption edge was shifted to higher wavelengths, accompanied by a greater absorption in the visible range and narrowed direct and indirect optical band gaps. The improved visible light photocatalytic activity of hematite nanorods in the heterogeneous photo-Fenton process by moderate Cr doping was measured, which can be attributed to the modifications in electronic structure and optical properties.

Enhanced mineralization of Reactive Black 5 by waste iron oxide via photo-Fenton process

Advanced oxidation process is a promising technology for the treatment of azo dye wastewater, owing to its high degradation performance and less secondary contamination. Herein, the mineralization of azo dye Reactive Black 5 (RB5) by the heterogeneous photo-Fenton process was investigated in a three-phase fluidized bed reactor. The waste iron oxide (denoted as BT) obtained from tannery wastewater process with Fenton’s reagent was selected as a heterogeneous catalyst. The introduction of BT to the UV/H2O2 process (UV/H2O2/BT) shows obviously higher mineralization efficiency because ferric complexes of carboxylic acid, the degradation intermediates of RB5, could be readily decomposed by UV irradiation. The decolorization was achieved by homogenous photo-Fenton reaction induced by leached iron, while the mineralization was contributed to heterogeneous oxidation. Under the conditions of 254 nm UV irradiation, 19.00 mM H2O2, 2.0 g L–1 catalyst loading and natural pH0 of 5.0, 90.2% TOC removal of RB5 could be achieved. The catalyst indicated an acceptable stability and reusability after four cycles. The proposed heterogeneous photo-Fenton process with stable performance is environmental-friendly for the mineralization of RB5.

Discoloration of alizarin red on thin films of Fe (III)-tetracarboxyphenyl porphyrin deposited on silicon oxide

Alizarin Red is a water soluble anthraquinone dye used extensively in the textile industry as a staining agent and is considered to be one of the most recalcitrant and durable pollutants. Fenton reaction can be used to destroy a wide variety of organic compounds: a ferrous ion reacts with hydrogen peroxide (H2O2) to form hydroxyl radical (HO•) which is a powerful oxidizing agent. The rate of this reaction could be increased when exposed o UV–vis light, this method is known as photo-assisted Fenton process and constitutes an attractive alternative of advance oxidation process. In this work, we studied the alizarin red dye photocatalytic discoloration through heterogeneous Photo-Fenton process induced by visible light; we used tetra (4-carboxyphenyl) porphyrin iron (III) adsorbed on silicon dioxide thin films. The characterization of the catalyst was carried out by UV-Vis, diffuse reflectance and IR-FT; The tests were carried out at three (3) pH values 1.0, 3.0 and 5.0; finally, the kinetic model described by Langmuir-Hinshelwood was used to obtain kinetic parameters for photo-discoloration process. The results showed that at pH = 1.0 highest alizarin red photo-discoloration percentage was reported; furthermore, after applied the pseudo-first order model, we obtained rate constants (k) for discoloration process that finds the highest k value was 1.1x10-2 min-1. The hydroxyl radicals were detected by chemical trapping through indirect fluorescence of the 2-hydroxyterephthalic acid. Photo-Fenton processes based on heterogeneous catalysis systems solve part of these environmental problems providing an easy separation and recovery of the catalyst from the treated wastewater, wherein it is noncorrosive, and, besides, it is environmentally friendly.

Fabricating Fe3O4-schwertmannite as a Z-scheme photocatalyst with excellent photocatalysis-Fenton reaction and recyclability

Here we reported an effective method to solve the rate-limiting steps, such as the reduction of Fe3+ to Fe2+ and an invalid decomposition of H2O2 in a conventional Fenton-like reaction. A magnetic heterogeneous photocatalyst, Fe3O4-schwertmannite (Fe3O4-sch) was successfully developed by adding Fe3O4 in the formation process of schwertmannite. Fe3O4-sch shows excellent electrons transfer ability and high utilization efficiency of H2O2 (98.5%). The catalytic activity of Fe3O4-sch was studied through the degradation of phenol in the heterogeneous photo-Fenton process. Phenol degradation at a wide pH (3 - 9) was up to 98% within 6 min under visible light illumination with the Fe3O4-sch as heterogeneous Fenton catalyst, which was higher than that using pure schwertmannite or Fe3O4. The excellent photocatalytic performance of Fe3O4-sch is ascribed to the effective recycling between Fe3+ and Fe2+ by the photo-generated electron, and also profit from the formation of the “Z-Scheme” system. According to the relevant data, photocatalytic mechanism of Fe3O4-sch for degrading phenol was proposed. This study not only provides an efficient way of enhancing heterogeneous Fenton reaction, but also gives potential application for iron oxyhydroxysulfate mineral.

Study on the efficient removal of azo dyes by heterogeneous photo-Fenton process with 3D flower-like layered double hydroxide.

As organic dyes are the main pollutants in water pollution, seeking effective removal solutions is urgent for humans and the environment. A novel environmentally friendly three-dimensional CoFe-LDHs (3D CoFe-LDHs) catalyst was synthesized by one-step hydrothermal method. Scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectra, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller technique as well as UV-Vis diffuse reflectance spectra were used to characterize the prepared samples. The experimental results revealed that 3D CoFe-LDHs exhibited a rapid decolorization of methyl orange and Rhodamine B by heterogeneous photo-Fenton process after reaching the adsorption equilibrium, and the final decolorization efficiency reached 91.18% and 93.56%, respectively. On the contrary, the decolorizing effect of 3D CoFe-LDHs on neutral blue was relatively weak. The initial concentrations of azo dyes, pH and H2O2 concentration affected the decolorization of dyes and the catalyst maintained excellent reusability and stability after reuse over five cycles. The quenching experiments found that •OH, •O2 - and h+ were the main active substances and reaction mechanisms were further proposed. The study suggests that the synergistic effect of photocatalysis and Fenton oxidation process significantly improved the removal of azo dyes and the synthesized catalyst had potentially promising applications for difficult-to-biodegrade organic pollutants in wastewater.

Photodegradation of Cyproheptadine using heterogeneous iron oxide–oxalate complex system under UV illumination

The development of high-performance advanced oxidation processes using UV irradiation energy has become a hot topic. A novel approach for the removal of organic compounds by an advanced oxidation process using an iron oxide catalyst and oxalate was proposed and investigated in this paper.Here, the removal of Cyproheptadine (CPH), a pharmaceutical compound, by a heterogeneous iron oxide–oxalate complex system with iron oxide Magnetite nanoparticles Fe3O4 (Fe2+/Fe3+ species) (MGN) was described and compared with heterogeneous photo-Fenton and homogeneous photo-Fenton processes. Thereafter, the influence of the basic operational parameters on the heterogeneous iron oxide–oxalate complex system was performed to enhance the process efficiency. The concentrations of formed H2O2 and formed Fe(II) ions during the process were determined over the range of conditions studied. It was found that the rate constant of CPH degradation by heterogeneous iron oxide–oxalate complex process is over 5.3-times and 13.5-times higher than that obtained by the heterogeneous photo-Fenton and the homogeneous photo-Fenton processes, respectively. The results show that the removal of CPH and the generation of each of H2O2 and Fe(II) depended strongly on the basic operational parameters on the heterogeneous iron oxide–oxalate complex system. The TOC measurements showed 80 % mineralization of a 10 mg L−1 solution of CPH after 180 min of treatment using heterogeneous iron oxide–oxalate complex process and over 99.5% of COD can be removed after 180 min of irradiation treatment. Increasing the solution pH rapidly decreased CPH rate constant. Conversely, CPH removal efficiency increased with increasing MGN concentrations up to 1.5 g L−1. The increase in the CPH concentration had a slightly negative effect on its degradation efficiency. The catalyst reusability study confirmed that MGN can be reused but not as reactive as the first use. The results have demonstrated the high performance of heterogeneous iron oxide–oxalate complex system using iron oxide Magnetite nanoparticles in organic contaminants degradation in industrial wastewater.

The degradation of BPA on enhanced heterogeneous photo-Fenton system using EDDS and different nanosized hematite.

Photo-Fenton processes have been widely studied in wastewater treatment. In this research, the degradation of bisphenol A (BPA) was carried out in a new heterogeneous photo-Fenton process. The ethylenediamine-N,N'-disuccinic acid (EDDS) was used as chelating agent in this system with two different kinds of commercially available nanosized hematite (30nm and 80nm) addition. The results showed that the present of EDDS could enhance the degradation efficiency. And can be concluded that the degradation efficiency is better in the system with 30nm hematite. The TEM, XRD, and specific surface area were conducted to understand the different characteristics of the two size hematite. The adsorption experiments of BPA and EDDS on hematite proved that there was little adsorption of BPA while the EDDS was adsorbed much more on hematite, which has confirmed Fe(III) and EDDS can form Fe(III)-EDDS complex. The effects of different parameters including hematite loading, H2O2, and EDDS concentrations on the degradation process were investigated. According to the results, the optimum condition for BPA degradation using 30nm (0.8gL-1 hematite, 0.1mmolL-1 H2O2, and 1.2mmolL-1 EDDS) and 80nm (0.6gL-1 hematite, 0.05mmolL-1 H2O2, and 1.2mmolL-1 EDDS) hematite were selected. It was confirmed that the ·OH plays an important role in the oxidation process through attacking the BPA molecule and produce hydroxyl addition derivative. In addition, O2 can react with electron (e-) and holes (h+) produced by iron oxide under UV irradiation to create 1O2, which could work as potential reactive species to oxidize BPA.