Heterogeneous photo-Fenton Oxidation Research Articles

Facile and scalable synthesis of Fe-based metal organic frameworks for highly efficient photo-Fenton degradation of organic contaminants

Fe-based metal organic frameworks (Fe-MOFs) being a newly developed photo-Fenton catalyst, have gained ever-increasing attention for environmental remediation, but have been limited by high synthesis cost (high energy-consumption and low yield). In this work, economical and scalable synthesis of Fe-BDC1 (BDC denotes as terephthalic acid) was achieved via facile stirring under ambient condition, and its adsorptive, photocatalytic, Fenton-like and photo-Fenton performances were comprehensively explored against contaminants removal. In comparison, synthesized Fe-BDC2 with the common solvothermal method, the yield of Fe-BDC1 increased 3.4 times. Also, its adsorption capacity towards Rhodamine B (Rh. B) increased about 5.85 times. Moreover, the significantly improved degradation of Rh. B was observed in the Fenton-like and photo-Fenton systems with the increased reaction rate constants up to 4.90 and 2.33 times, respectively. This enhanced catalytic performance of Fe-BDC1 was mainly attributed to the enlarged specific surface area (SSA) and favorable electron separation and migration, resulting into the accelerated ≡Fe(II)/≡Fe(III) cycle and increased yield of reactive oxidative species (ROSs). Additionally, the unique light-induced adsorption enhancement further strengthened the contaminants removal. Fe-BDC1 as photo-Fenton catalyst was found superior over conventional catalysts in terms of advantages including: low dose requirement of catalysts (decrease in an order of magnitude) and H2O2, wide pH working range (3.0–9.0), excellent reusability and stability, universal removal behavior against all organic pollutants, and remarkable synergism between photocatalysis and Fenton-like process with synergistic factor of 77.23%. Moreover, the Fe coordinative unsaturated sites (Fe CUSs) and ·OH were determined as the active sites and the main ROSs, respectively, responsible for highly efficient pollutant degradation. This work gives a feasible solution for the preparation of Fe-MOFs with low synthesis cost and high yield, paving ways for their practical mass application in heterogeneous photo-Fenton oxidation.

Effects of the heterogeneous photo-Fenton oxidation and sulfate radical-based oxidation on atrazine degradation

Effects of the heterogeneous photo-Fenton oxidation and sulfate radical-based oxidation on atrazine degradation

Degradation of aqueous organic dye pollutants by heterogeneous photo-assisted Fenton-like process using natural mineral activator: Parameter optimization and degradation kinetics

Degradation of organic pollutants by heterogeneous Fenton-based advanced oxidation processes has been proved to be an efficient method. The use of naturally occurring catalysts as H2O2 activators is of particular interest in environmental remediation. This work applied a low-cost and eco-friendly natural mineral under UV-light irradiation to degrade organic dye in water. To study the performance of the natural mineral in photo-Fenton oxidation, methylene blue (MB) was employed as a model dye pollutant. The morphology and chemical composition of the natural mineral were characterized using various techniques. The effects of different experimental conditions such as the initial pH of the solution, the amount of catalyst, and initial dye concentrations on the degradation efficiency were investigated. The degradation of methylene blue reached 91.3% at optimum reaction conditions; 0.1g catalyst and 100 mg L‒1 H2O2 concentrations for 10 mg L‒1 initial dye concentration after 180 min of treatment. The pseudo-first-order kinetic model exhibited a better correlation coefficient (R2 > 0.98) in explaining the degradation kinetics of MB. The applied natural mineral showed good catalytic activity and will open a door towards large-scale wastewater purification from dyes. Furthermore, the plausible mechanism of the heterogeneous photo-Fenton oxidation is discussed.

Heterogeneous photo-fenton oxidation degradation of methyl orange using Alg-m, Alg-HAp, and Alg-mHAp catalysts

ABSTRACT Removal of methyl orange (MO) anionic dye was investigated by composite beads of sodium alginate-magnetic hydroxyapatite (Alg-mHAp), sodium alginate-magnetite (Alg-m), and sodium alginate-hydroxyapatite (Alg-HAp) as catalysts of heterogeneous photo-Fenton process. Evaluation of XRD and FT-IR analysis proved the presence of magnetite and hydroxyapatite nanoparticles in the structure of synthesised catalysts. SEM analyses showed that the surface of the Alg-mHAp catalyst is rougher than the other two catalysts. The results demonstrated the effluent discoloration of 79.41%, 71.42, and 84.28% for Alg-m, Alg-Hap, and Alg-mHAp, respectively, at an optimum pH = 3. By increasing the pH to more than 3, the removal rate decreased. In addition, it was found that by increasing the hydrogen peroxide concentration from 0.5 to 3 , photo-Fenton activity can be further enhanced to effectively degrade MO. However, with increasing the concentration of H2O2 from 3 to 20 , the removal percentage of Alg-m, Alg-HAp, and Alg-mHAp catalysts decreased to 92.70%, 86.20%, and 95.62, respectively. The results revealed with increasing initial dye concentration, the removal percentage decreased for all three catalysts. Also, by increasing the catalyst dosage from 0.5 to 2 , the removal percentage for Alg-m, Alg-HAp, and Alg-mHAp catalysts increased 16, 21, and 12%, respectively. Furthermore, it was determined that as the UV intensity increased, the removal percentage increased by an average of 26%. The first-order kinetic equation was most consistent with the experimental results of MO degradation in all three catalysts. This study confirmed the feasibility of a heterogeneous photo-Fenton system of Alg-mHAp for the highly efficient degradation of MO in wastewater.

Improved degradation of metronidazole in a heterogeneous photo-Fenton oxidation system with PAC/Fe3O4 magnetic catalyst: biodegradability, catalyst specifications, process optimization, and degradation pathway

Improved degradation of metronidazole in a heterogeneous photo-Fenton oxidation system with PAC/Fe3O4 magnetic catalyst: biodegradability, catalyst specifications, process optimization, and degradation pathway

Catalytic activity comparison of natural ferrous minerals in photo-Fenton oxidation for tertiary treatment of dyeing wastewater.

Natural ferrous minerals are readily available and recyclable catalysts in photo-Fenton-like oxidation for wastewater treatment. In this work, typical ferrous oxide and sulfide minerals including magnetite, chalcopyrite, and pyrrhotite were exploited as catalysts in heterogeneous photo-Fenton oxidation for purification of biological effluent of dyeing wastewater. In a wide initial pH range (3.0~7.5), ferrous mineral-based heterogeneous photo-Fenton-like reactions were proven to be effective on the oxidation of recalcitrant pollutants. COD removals achieved 60.57%, 58.83%, and 57.41% using pyrrhotite, chalcopyrite, and magnetite, respectively, as catalyst under ultraviolet irradiation of 220~275 nm at H2O2 concentration of 9.8 mM. The corresponding COD removals were 51.75% and 34.09% with or without ferrous sulfate additions in UV/H2O2 systems. Minerals exhibited excellent stability and reusability with photo-catalytic activity reduction of less than 10% in the reuse of 5 cycles. Dissolved iron concentrations were determined to be 1.86 mg L-1, 4.62 mg L-1, and 7.53 mg L-1 for magnetite, chalcopyrite, and pyrrhotite, respectively, at pH 3 and decreased to zero in neutral pH environment, which were much lower than those required for homogenous Fenton reaction. It was deduced that oxidation of recalcitrant pollutants was mainly catalyzed by Fe(II) on the mineral surface. The more reactive oxygen species such as hydroxyl radicals were resulted from the reaction of surface Fe (II) with H2O2, H2O2 photolysis, and charge separation of minerals under UV irradiation.

Highly dispersed titania-supported iron oxide catalysts for efficient heterogeneous photo-Fenton oxidation: Influencing factors, synergistic effects and mechanism insight

Titania (TiO2) supported iron oxides (Fe-TiO2) are ideal catalysts to be applied in heterogeneous photo-Fenton oxidation (HPFO) for wastewater treatment because of the capabilities of TiO2 in photocatalysis and iron oxides in interfacial H2O2 activation. It is important to understand the influences of the structural parameters of Fe-TiO2 catalysts and the complicated interplay between TiO2 and iron oxides on the performance of HPFO. In this paper, a series of Fe-TiO2 catalysts are obtained through a facile solid-phase synthesis method. The iron loading content and the calcination temperature are systematically adjusted to tune the crystal phase, size, anatase/rutile ratio and density of oxygen vacancy (OV) site of TiO2, the dispersing state of iron species, and the interfacial structure of the Fe-TiO2 catalysts. Then, the performance of these catalysts in HPFO for degrading methylene blue (MB) are comparatively studied. Correlations between the performance and various structural properties of the catalysts are clarified. The interplay between TiO2 and iron oxides in the HPFO process is elucidated. The insight reaction mechanism is also discussed. Under optimized conditions (an iron loading of 1 wt% and a temperature of 600 °C), Fe-TiO2 catalysts with iron lattice doping, well-dispersed ultrasmall α-Fe2O3 nanoparticles, appropriate anatase/rutile ratios and abundant OV sites can be obtained. The anatase-rutile-Fe2O3 heterojunction, ultrasmall α-Fe2O3 nanoparticles and OV sites in the optimized catalysts work synergistically to improve the charge migration and interfacial activation of H2O2, leading to superior HPFO performance for MB degradation and mineralization.

Nanostructured semiconductor supported iron catalysts for heterogeneous photo-Fenton oxidation: a review

This review summarizes the typical progress in nanostructured semiconductor supported iron catalysts and their applications in heterogeneous photo-Fenton oxidation.

Heterogeneous photo-Fenton oxidation of lignin of rice husk alkaline hydrolysates using Fe-impregnated silica catalysts

ABSTRACT Present work shows results of a study on heterogeneous Fenton-like degradation of lignin alkaline hydrolysates formed in the process of obtaining a fibrous mass from rice husk. Fe-impregnate biogenic amorphous silica Fe/RH-SiO2 obtained from rice husk was used as a catalyst. Using IR spectroscopy, X-ray diffraction and EDX analysis it was shown that iron(III) oxide in the form of hematite is present on the catalyst surface. Phenol was used for preliminary assessment of catalytic activity of the catalyst Fe/RH-SiO2. The degree of degradation of phenol by the UV/visible radiation/Fe/RH-SiO2/H2O2 system reaches 90%. The catalytic activity of Fe/RH-SiO2 was studied in the reaction of lignin degradation of rice husk alkaline hydrolysates under ultraviolet and visible irradiation in the presence of hydrogen peroxide. The lignin solutions with COD: Н2О2 ratios from 1:2 to 1:16 were exposure under UV irradiation for 15-minute and the subsequent lightening on sunny days between 9 am and 8 pm in April for 7 days in the presence of a catalyst and without it. The catalyst concentration was 1.0 g L−1. After that, it was found the content of phenolic compounds in the presence of a catalyst is 2–20 times lower than without it. The COD with the COD: Н2О2 = 1:16 ratio in the presence of a catalyst decreases 1.5 times as compared with the initial solution, whereas without a catalyst it increases 13 times.

Catalytic Degradation of 4-Ethylpyridine in Water by Heterogeneous Photo-Fenton Process

In this work, the degradation of 4-ethylpyridine (4EP) in water by a heterogeneous photo-Fenton process (H2O2/Fe3O4/ultraviolet irradiation (UV)) was investigated. More rapid and effective 4EP degradation was obtained with H2O2/Fe3O4/UV than Fenton-like (H2O2/Fe3O4) and UV/H2O2, which is due to the larger production of hydroxyl radicals from the chemical and photolytic decomposition of H2O2. The operational conditions were varied during 4EP degradation experiments to evaluate the effects of pH, catalyst, concentration, and temperature on the kinetics and efficiency of H2O2/Fe3O4/UV oxidation. Under optimal conditions (100 mg/L 4EP, [H2O2] = 1000 mg/L, Fe3O4 = 40 mg/L, pH = 3 and room temperature, 300 rpm), 4EP was totally declined and more than 93% of the total organic carbon (TOC) was eliminated. Liquid chromatography analysis confirmed the formation of aromatic and aliphatic intermediates (4-hydroxypyridine, 4-pyridone, malonic, oxalic, and formic acids) that resulted in being mineralized. Ion chromatography analysis demonstrated the stoichiometric release of NH4+ ions during 4EP degradation by heterogeneous photo-Fenton oxidation. The reuse of the heterogeneous catalyst was evaluated after chemical and heat treatment at different temperatures. The heat-treated catalyst at 500 °C presented similar activity than the pristine Fe3O4. Accordingly, heterogeneous photo-Fenton oxidation can be an alternative method to treat wastewaters and groundwater contaminated with pyridine derivatives and other organic micropollutants. The combination of heterogeneous photo-Fenton oxidation with classical biological methods can be proposed to reduce the overall cost of the treatment in large-scale water treatment plants.

Synthesis of Fe3O4-Reduced Graphene Oxide Modified Tissue-Paper and Application in the Treatment of Methylene Blue

Graphene-based composites have received a great deal of attention in recent year because the presence of graphene can enhance the conductivity, strength of bulk materials and help create composites with superior qualities. Moreover, the incorporation of metal oxide nanoparticles such as Fe3O4 can improve the catalytic efficiency of composite material. In this work, we have synthesized a composite material with the combination of reduced graphene oxide (rGO), and Fe3O4 modified tissue-paper (mGO-PP) via a simple hydrothermal method, which improved the removal efficiency of the of methylene blue (MB) in water. MB blue is used as the model of contaminant to evaluate the catalytic efficiency of synthesized material by using a Fenton-like reaction. The obtained materials were characterized by SEM, XRD. The removal of materials with methylene blue is investigated by UV-VIS spectroscopy, and the result shows that mGO-PP composite is the potential composite for the color removed which has the removal efficiency reaching 65% in acetate buffer pH = 3 with the optimal time is 7 h.
 Keywords
 Graphene-based composite, methylene blue, Fenton-like reaction.
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Synergistic effect of UV pretreated Fe-ZSM-5 catalysts for heterogeneous catalytic complete oxidation of VOC: A technology development for sustainable use

In this work, the performance of benzene, toluene, ethylbenzene, and xylene (BTEX) removal and degradation from gas, air streams on UV pretreated Fe-ZSM-5 in a batch reactor at room temperature were studied. The Fe-ZSM-5 zeolite catalyst was prepared by hydrothermal reaction method. The influence of UV pre-irradiation time on the removal of BTEX were assessed by varying the time, ranging from 15min to 60smin. Then, sustainability of the activation of the catalyst resulted by UV pretreatment was studied by the four-cycle experiment with one time UV irradiation and after each cycle irradiation followed by BTEX removal after every cycle respectively. The results of BTEX removal depicted that 30min of UV pretreatment was sufficient for complete organics removal. The UV pretreatment effect on the catalytic oxidation and the stability of the catalyst were studied by modern instrumental techniques. The novelty of the process was the sustainable reuse of catalyst with persistent VOC removal, which works on the -adsorption-oxidation-regeneration-adsorption- cycle, which was confirmed by the characterization studies of the catalyst after four runs. The results revealed that the change in the structure, stability, morphology, and removal efficiency of the catalyst during the experiments was negligible. The VOC degradation mechanism studies showed that the oxidation occurs due to the formation of free radicals as well as hydroxyl ions, so named it heterogeneous photo-Fenton oxidation. The residual materials analysis showed the complete mineralization of VOC except small amount of acetone as oxidation product. Lastly, the kinetics of the VOC removal was studied.

Enhanced heterogeneous photo-Fenton process modified by magnetite and EDDS: BPA degradation.

In this research, magnetite and ethylenediamine-N,N'-disuccinic acid (EDDS) are used in a heterogeneous photo-Fenton system in order to find a new way to remove organic contaminants from water. Influence of different parameters including magnetite dosage, EDDS concentration, H2O2 concentration, and pH value were evaluated. The effect of different radical species including HO· and HO2·/O2·- was investigated by addition of different scavengers into the system. The addition of EDDS improved the heterogeneous photo-Fenton degradation of bisphenol A (BPA) through the formation of photochemically efficient Fe-EDDS complex. This effect is dependent on the H2O2 and EDDS concentrations and pH value. The high performance observed at pH6.2 could be explained by the ability of O2·- to generate Fe(II) from Fe(III) species reduction. GC-MS analysis suggested that the cleavage of the two benzene rings is the first degradation step followed by oxidation leading to the formation of the benzene derivatives. Then, the benzene ring was opened due to the attack of HO· radicals producing short-chain organic compounds of low molecular weight like glycerol and ethylene glycol. These findings regarding the capability of EDDS/magnetite system to promote heterogeneous photo-Fenton oxidation have important practical implications for water treatment technologies.

Efficient removal of cadmium and 2-chlorophenol in aqueous systems by natural clay: Adsorption and photo-Fenton degradation processes

Abstract Adsorption and photo-Fenton processes were used as handy tools to ascertain the capability of natural clays to remove cadmium (Cd) and 2-chlorophenol (2-CP) from aqueous solution. Natural Fe-rich clay collected from Tejera-Esghira in Medenine area, south Tunisia, was used as a catalyst in the heterogeneous photo-Fenton oxidation of 2-CP in aqueous solution. Clay samples were acid activated to improve their adsorptive capacity for the removal of Cd. Experimental results indicated that the adsorption of Cd ions onto natural red clay of Tejera-Esghira followed the pseudo-second-order kinetic model. Langmuir model was found to describe the equilibrium data with the calculated maximum adsorption capacity of 23.59 mg g−1 for acid-activated clay. Photo-Fenton experiments proved high activity of the natural clay catalyst, which was able to completely degrade the phenol present in the treated solution after 30 min and in the presence of ultraviolet light C (UV-C). Total organic carbon and gas chromatography analysis confirmed a 2-CP degradation mechanism toward an almost complete mineralization of the organic compound.

Mathematical analysis of the heterogeneous photo-Fenton oxidation of acetic acid on structured catalysts

In this paper, we analyse the model for the UV-C photo-Fenton degradation of acetic acid using \(LaFeO_{3}\) heterogeneous structured catalyst with a monolithic structure. The model is based on the occurrence of hydrogen peroxide photolysis and acetic acid oxidation in the heterogeneous phase, assumed first-order and Eley–Rideal type kinetics respectively. The main objective is to propose an analytical solution for the concentrations of \(\hbox {CH}_{3}\hbox {COOH}\) and \(\hbox {H}_{2}\hbox {O}_{2}\). A powerful analytical method called Homotopy Perturbation Method (HPM) has been employed to obtain approximate analytical solutions. The accuracy of the analytical solution is tested with the numerical solution. In this work the numerical solution of the problem is reported using SCILAB program. Stability Analysis of this model is also explained. The obtained analytical solution in comparison with the numerical and stability analysis is found to be in satisfactory agreement.

Photo-Fenton oxidation of phenol over a Cu-doped Fe-pillared clay

A Cu-doped Fe-pillared Tunisian clay (Cu/Fe–PILC) was synthesized and used as a catalyst in the heterogeneous photo-Fenton oxidation of phenol in aqueous solution. Textural, structural and chemical characterization pointed to successful pillaring and incorporation of the Cu active phase. Photo-Fenton experiments proved the high activity of the Cu/Fe–PILC catalyst, which was able to completely mineralize the phenol present in the treated solution after a reaction time of 40 min and in the presence of UV-C light. Moreover, the catalytic activity was not influenced by the pH of the initial phenol solution, over a wide range of pH from 3 to 7. An optimal dosage of H2O2 and of the catalyst was found. Phenol degradation was found to be slower in the presence of UV-A irradiation, needing longer reaction times. Negligible metal leaching and catalyst reutilization without noticeable loss of activity point to an excellent catalytic stability for this Cu/Fe–PILC catalyst.

Heterogeneous photo-Fenton oxidation of methylene blue using CdS-carbon nanotube/TiO2 under visible light

Heterogeneous photo-Fenton oxidation using CdS/multi-walled carbon nanotube-TiO2 (CdS/MWCNT-TiO2) under visible light relied on combination of the photocatalytic, photo-Fenton and photo-sensitizing oxidation. The photo-Fenton reactions resulted in much faster and higher removal of methylene blue and total organic carbon than the dark Fenton oxidation and the photocatalytic degradation alone at the selected conditions. The optimum molar ratio of [methylene blue]:[H2O2]:[Fe3+] (1:12:3.4) in the photo-Fenton oxidation indicated cost-effectiveness of the process. The scavenging tests of the hydroxyl radicals and the valence holes suggested that the hydroxyl radical-driven oxidation was the major step among the multiple reactions in the photo-Fenton oxidation.

Influence of Operational Parameters in the Heterogeneous Photo-Fenton Discoloration of Wastewaters in the Presence of an Iron-Pillared Clay

An iron-pillared Tunisian clay (Fe-PILC) was prepared and used as the catalyst in the heterogeneous photo-Fenton oxidation of Red Congo and Malachite Green in aqueous solution. The catalyst Fe-PILC was characterized by XRF, XRD, BET, and FTIR methods. This physicochemical characterization pointed to successful iron pillaring of the clay. The influence of several operational parameters such as the pH, H2O2 concentration, catalyst dosage, and initial dye concentration was evaluated. A solution pH in the range 2.5–3, the addition of 8 mL of 200 mg/L H2O2, and a catalyst dosage of 0.3 g/L appeared as the most favorable reaction conditions for achieving complete discoloration, either for Red Congo or Malachite Green, although oxidation was found to be slower and more complicated in the former case. The kinetics of discoloration of both dyes followed a pseudo-first-order rate law. In general, 20 min of UV irradiation was enough to achieve 100% discoloration of the aqueous solution. UV–vis and chemical oxygen demand measurements indicated, however, that longer reaction times of around 1 h were required for achieving dye mineralization. Leaching tests confirmed a very low amount of dissolved iron and good stability of the catalyst, with almost unaltered discoloration efficiency upon three cycles. Hence, taking into account the favorable photocatalytic properties and low leaching of iron ions, such iron-pillared clay can be considered a promising catalyst for dye wastewater treatment.

Photocatalytic Fenton oxidation of sodium dodecyl sulfate solution using iron-modified zeolite catalyst

Abstract The heterogeneous photo-Fenton oxidation of sodium dodecyl sulfate (SDS) solutions was investigated in a quartz batch reactor using an artificial UV light source. Fe-modified zeolite was used as a heterogeneous catalyst in the process. The effect of various process variables on SDS removal performance was evaluated by examining temperature, pH, H2O2 dosage, catalyst loading, initial SDS concentration and light intensity. The optimal operational parameters were found as follows: temperature 35°C, solution pH 7.5, 15 mmol H2O2 dosage, and 1 g/L catalyst loading. Stability and the reuse of the catalyst were also tested. Comparison with homogenous photo-Fenton process was also performed by analyzing SDS removal rate. Kinetic investigation of removal process based on different kinetic models was evaluated. The results showed that the first-order kinetic model was in good correlation with experimental data.

Mathematical modelling of the heterogeneous photo-Fenton oxidation of acetic acid on structured catalysts

This work focused on the development and the validation of a mathematical model for the UV-C photo-Fenton degradation of acetic acid using a LaFeO3 heterogeneous structured catalyst with a monolithic structure. A combined study of the evolved gases and the liquid phase was conducted. The experimental results led to the identification of the main reactions that occur in the system: the complete mineralisation of acetic acid by H2O2 due to the presence of the catalyst and the decomposition of H2O2 to water and O2 in the homogeneous phase. A mathematical model was then developed using Eley–Rideal-type kinetics for the acetic acid consumption and first-order kinetics for the photolysis of hydrogen peroxide. The apparent kinetic constants were estimated, and the accuracy of the model was tested under different experimental conditions to evidence the predictive capability of the model. A very good agreement between the mathematical model calculations and the experimental data obtained in the presence of various H2O2 dosages was achieved. The results demonstrate that the continuous addition of H2O2 during the photo-Fenton reaction ensures the fruitful utilisation of the produced hydroxyl radicals in the acetic acid oxidation reaction to minimise the oxidant consumption and maximise the TOC removal in a shorter irradiation time.