Heterogeneous Fenton Process Research Articles

Synergistic degradation of refractory organic pollutant by underwater bubbling plasma combined with heterogeneous Fenton process

Excessive discharge of the refractory organic pollutants endangers the development of the society and economy, thus seeking an efficient wastewater abatement method is an urgent need. Herein, Iron (Ⅱ) sulfide (FeS) was employed as the heterogeneous catalyst and coupled with underwater bubbling plasma (UBP) for the elimination of the refractory organic pollutant, malachite green (MG). FeS catalyst was synthesized using the solvothermal method and subsequently characterized comprehensively, focusing on its microstructure, specific surface area, chemical bonds and elements valence states. The UBP system combined with FeS (UBP/FeS) exhibited the robust synergism with a maximum synergistic factor of 1.89. The MG degradation percentage and rate constant were up to 94.7% and 0.237 min−1 within 12 min. The parameter experiments revealed that FeS dosage, pulse frequency, initial MG concentration and solution conductivity of 150 mg/L, 56 Hz, 5 mg/L and 21.8 μS/cm, respective, were more conducive for MG elimination. The MG removal efficiency reached 86.2% after five consecutive applications of FeS. Reactive substances including ·OH, ·O2−, eaq, O3 and H2O2 were confirmed to contribute to MG elimination. Additionally, the conversion circle between ≡ Fe(Ⅱ) and ≡ Fe(Ⅲ) promoted the catalytic conversion of H2O2 and O3 into ∙OH. The comparison of UV–vis spectra and total organic carbon of MG solution before and after reaction revealed the superior degradation of MG in the UBP/FeS system. Hypotheses regarding to the decomposition pathways of MG were formulated based on the identified intermediates. The toxicity level of MG solution was lightened after reaction. The above results indicate that UBP/FeS has the advantages of quick degradation and high efficiency, representing a promising approach for refractory pollutants treatment.

Evaluation of Iron-Modified Biochar from Sugarcane Bagasse and Heterogeneous Fenton Process for Batik Dye Removal

Evaluation of Iron-Modified Biochar from Sugarcane Bagasse and Heterogeneous Fenton Process for Batik Dye Removal

Removal of tetracycline from aqueous solution via Fenton process using iron-impregnated bamboo biochar

Abstract Tetracycline (TC) is a pharmaceutical that has been used extensively that its presence in water sources causes detriment to both aquatic life and human health. TC is not completely removed in wastewater treatment processes and could enter the environment through effluent and sludge. This study evaluated the potential of iron-impregnated bamboo biochar (Fe-biochar) as catalyst in the removal of tetracycline from aqueous solution via Fenton process. Characterization via Fourier transform infrared (FTIR) and energy dispersive X-ray spectroscopy (EDX) analyses verified the successful iron impregnation on biochar. TC removal was determined at 357nm absorbance through UV-Visible spectroscopy. Highest TC removal of 63.24% was achieved under conditions of 75 mg Fe-biochar, 0.45 M H2O2, and pH 5. Experimental data were assessed using the three factors Box-Behnken response surface experimental design where Fe-biochar dosage, H2O2 concentration, and solution pH were found to be significant parameters in TC removal. Furthermore, it was determined that the data fitted well in a reduced-cubic model with high coefficient of determination (R2 = 0.9990) which indicates good regression. The optimum conditions were found to be 39.44 mg Fe-biochar dosage, 0.05 M H2O2, and pH 4, with TC removal efficiency of 33.90%. Overall, the results of this study suggested that Fe-impregnated bamboo biochar can be used as an effective catalyst in removing tetracycline from aqueous solution via heterogeneous Fenton process.

Degradation of tetracycline in water using hydrogen peroxide activated by soybean residue-derived magnetic biochar

Tetracyclines (TCs) are the second most commonly used antibiotics worldwide, utilized both in medical treatments and animal husbandry. Although effective against various infectious diseases, TC residues persist in the environment and contribute to the emergence of antibiotic-resistant pathogens, posing significant risks to human health. This study employed the heterogeneous Fenton process to degrade TC using soybean residue-derived magnetic biochar (Fe-SoyB) as the catalyst. The Fe-SoyB sample was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and superconducting quantum interference device (SQUID) techniques. The effects of key parameters, including pH, H2O2 concentration, catalyst dosage, and initial TC concentration, on TC degradation were investigated. The results indicated that the TC removal efficiency decreased with increasing initial TC concentration, while it was improved with higher H2O2 concentrations and greater catalyst dosages. The optimal conditions for the Fenton-like process were determined to a pH of 3, a H2O2 concentration of 245 mmol/L, an initial TC concentration of 800 mg/L, and a catalyst dosage of 0.75 g/L, achieving a removal efficiency of 90% after 150 min. Additionally, the TC removal efficiency of the Fe-SoyB system varied significantly across different water matrices, with 87.1% for deionized water, 78.5% for tap water, and 72.5% for river water. The catalyst demonstrated notable stability, maintaining a TC removal efficiency of 79.7% after three cycles of use. Overall, Fe-SoyB shows promise as a cost-effective catalyst for the elimination of organic pollutants in aqueous solutions.

Efficient treatment of polyacrylamide wastewater by cascade heterogeneous Fenton and magnetic flocculation process

A large quantity of polyacrylamide containing wastewater is generated during polymer flooding every year and it poses great threats to the environment. As highly efficient technology for polyacrylamide wastewater treatment with potential for engineering application is rare, magnetic flocculation represents a promising alternative. It usually takes minutes for complete sedimentation to occur. However, we found in experiments that viscosity reduction in advance was essential to improve the performance of magnetic flocculation. So, a cascade of heterogeneous Fenton and magnetic flocculation process was proposed. Effect of Fe3O4 dosage, flocculants type and dosage, flocculation pH, stirring conditions and flocculation methods on the removal efficiency of PAM was investigated. The cascade process turned out to be one of the most efficient technologies and achieved 92% PAM removal rate in the shortest time (45 min) for 500 mg/L of PAM when Fe3O4 dosage was 1.5 g/L, AlCl3 dosage was 100 mg/L and flocculation pH was 8.0 under optimized stirring conditions. Nano-Fe3O4 exhibited good stability after at least 3 successive runs. The water quality of polymer flooding wastewater from Nanyang Oilfield reached the required standards for reinjection after treatment by the cascade process. The study provides a new and highly efficient technology for PAM wastewater treatment with promising potential for engineering application.

Efficient water disinfection against antibiotic-resistant bacteria by visible-light heterogeneous photo-Fenton-like process with atomically dispersed Cu on graphitic carbon nitride as the catalyst

Waterborne microbial contamination poses significant environmental and health risks. Photocatalytic heterogeneous Fenton and Fenton-like processes can offer efficient pathogen removal, with benefits in recycling, solid–liquid separation, and byproduct avoidance. However, their low reaction efficiency and slow kinetics for low-valence metal regeneration are limitations. This study addresses these challenges by incorporating atomically dispersed Cu onto graphitic carbon nitride (g-CN) as a single-atom catalyst (SAC). The Cu atoms are stabilized by pyridinic N atoms through coordination, forming Cu-N4 catalytic sites that enhance photogenerated charge carrier transfer. This leads to a more efficient synergistic photocatalytic-Fenton-like reaction, generating more hydroxyl radicals and achieving effective water disinfection. Results show a 7-log bacterial inactivation of antibiotic-resistant Acinetobacter baumannii within 8 min, surpassing prior photocatalytic-Fenton-like disinfection systems. Density functional theory calculations confirm improved hydrogen peroxide adsorption, electron transport, and electron-hole separation in the Cu-N4 structure. The catalyst’s durability and stability were demonstrated through extensive cycling experiments, ion interference tests, and disinfection trials in various water matrices. Additionally, the Cu-SAC@CN catalyst, loaded onto a polytetrafluoroethylene membrane, achieved a 99% bacterial eradication rate within 20 min. This study provides valuable insights into the potential applications of heterogeneous photocatalytic-Fenton-like systems for efficient eradication of waterborne bacteria.

Modified sono-Fenton process for oxidative degradation of chloramphenicol.

Oxidative degradation of chloramphenicol (CAP) using a hybrid approach (US/HA+/n-Fe2O3/SPC) involving sodium percarbonate (SPC; "solid H2O2" carrier), Fe2O3 nanoparticles (n-Fe2O3; H2O2 decomposition catalyst), hydroxylamine in its protonated form (HA+; Fe (III) to Fe (II) reducer), and ultrasonic cavitation (to increase the generation of hydroxyl radicals) has been studied for the first time. The average size of n-Fe2O3 synthesized by the sonochemical method, as calculated according to the Debye-Scherrer equation, was ~ 18nm. The maximum degradation degree of CAP (83.1%) and first-order oxidative degradation rate constant of CAP as 1.253 × 10-3s-1 were achieved using the modified sono-Fenton process under the optimized conditions as the initial concentration of CAP - 50mg/L, the molar ratio of CAP:HA+:n-Fe2O3:SPC of 1:100:100:100, pH as 3, the temperature as 318K, the specific ultrasonic power as 53.3 W/L, and the treatment duration of 7200s. In general, the efficiency and intensity of CAP degradation increased with a decrease in the pH value, an increase in the molar ratio of CAP:HA+:n-Fe2O3:SPC, a decrease in the initial concentration of CAP, an increase in temperature, and showed a minor change with the specific power of US. The synergistic coefficient for the combination of the US and the heterogeneous Fenton process was 17.9. The active participation of hydroxyl radicals in the oxidative degradation of CAP using the modified sono-Fenton process was confirmed by scavenging experiments performedusing tert-butyl alcohol. The proposed process can be a promising direction in the remediation of pharmaceutical effluents with significant potential for commercial exploitation.

Overlooked pyrite-mediated heterogeneous Fenton processes: Mechanisms of surface hydroxyl radical generation and associated decontamination performance

Pyrite-based Fenton-like processes have been extensively studied for wastewater decontamination; however, most relevant studies placed excessive emphasis on the homogeneous Fenton reaction mediated by aqueous Fe2+, resulting in the proposed technologies facing issues such as additional acid requirements for pH adjustment and excessive iron sludge production. Herein, through in situ shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), custom dual-chamber reactor experiments, and a series of control experiments, significant hydroxyl radical generation was identified during the pyrite/H2O2 process, while the dominant reactive iron species was verified to the structural Fe sites on the pyrite surface, rather than structural Fe(II) in secondary iron minerals and surface adsorbed Fe2+. Consequently, even with significant suppression of the homogeneous Fenton pathway, the pyrite/H2O2 process exhibited significant degradation efficiency for sulfamethoxazole (SMX) at pH 4. Moreover, the pyrite/H2O2 process was found to selectively remove 50 μM of pollutants with high affinity for pyrite (bisphenol A, carbamazepine, nitrobenzene, and SMX), even in the presence of 50–100 mM methanol. Compared to the typical iron-based reductive catalyst (zero-valent iron, ZVI), pyrite mediated a Fenton process with greater potential for practical applications at pH 4, achieving a 43.75-fold reduction in iron sludge production and almost doubling the H2O2 utilization efficiency. Additionally, in contrast to ZVI, minimal iron oxide formed on the pyrite surface during the oxidation process. Thus, after seven cycles of degradation experiments, the decontamination efficiency of the pyrite/H2O2 process remained stable. These findings are crucial for understanding the complex environmental behavior of pyrite in both natural and engineering processes and provide a new perspective for the efficient utilization of pyrite resources as well.

Solar light driven degradation of piroxicam and paracetamol by heterogeneous photocatalytic fenton system: Process optimization, mechanistic studies and toxicity assessment

The widespread occurence of pharmaceutical pollutants seriously threatens the environment and human well-being. In the present study, zinc ferrite nanoparticles (ZnFe2O4 NPs) have been synthesized by co-precipitation method and used as photocatalyst for the degradation of two most commonly prescribed painkillers, piroxicam (PXM) and paracetamol (PCM), via heterogeneous Fenton process under the solar light. The synthesized ZnFe2O4 NPs showed a narrower band gap i.e. 1.87 eV, signifying the ability to efficiently work in visible light range. In context of photocatalytic applications, the operational conditions were optimized to achieve maximum degradation. PCM and PXM were completely degraded (100%) at the optimized photocatalytic dose (20 mg L−1), reaction time (180 min), initial drug concentration (10 mg L−1), and pH (6.0), which is close to the natural environment. The extent of mineralization as estimated by the reduction of total organic carbon (TOC) was observed to be ∼91 and 82% for PCM and PXM respectively. Kinetic studies revealed that photocatalytic degradation followed pseudo-first-order kinetics. Moreover, the ZnFe2O4 NPs retained ∼90 % of photocatalytic activity after five consecutive reaction cycles, showing remarkable reusability and stability of catalyst.

Heterogeneous Fenton process using GO@Fe3O4/Cu catalyst for the degradation of reactive dyes from aqueous solutions: modeling and optimisation

ABSTRACT Various industries such as textile, paper, rubber, plastic, and cosmetics use dyes to produce their products. Some dyes used in textile industries are teratogenic, carcinogenic, mutagenic, and dangerous for humans and other organisms. This study aimed to determine the amount of removal of reactive dyes from aqueous solutions during the heterogeneous Fenton process. In this study, iron oxide nanoparticles and copper nanoparticles were loaded on graphene oxide (GO). GO@Fe3O4/Cu catalyst was synthesised and applied to remove reactive dyes from aqueous solutions in a heterogeneous Fenton process. Contact time, pH, catalyst dose, dye concentration, and H2O2 dose were considered effective parameters. Experiments were designed according to the Box-Behnken design in the Design Expert software. Catalyst properties were determined using SEM, VSM, XRD, and FTIR analysis. The ANOVA showed that the selected statistical model with R2 0.965, p < 0.0001, and F-value 27.79 was significant. In the optimal conditions of pH 3, H2O2 dose 0.48 mL, catalyst dose 0.34 g/L, dye concentration 22 mg/L, and contact time 9 min, the degradation efficiency of Reactive Blue 21 (RB21), Reactive Red 195 (RR195) and Reactive Red 19 (RR19) were 92, 97, and 80%, respectively. The results showed that after 5 cycles of recycling, the catalyst had a high efficiency in pollutant removal and could be utilised many times for dye decomposition. GO@Fe3O4/Cu catalyst was successfully synthesised using a simple method. The heterogeneous Fenton process with a magnetic catalyst in the presence of H2O2 has a high potential to remove reactive dyes from the aqueous solution.

Modelling and optimization of fenton process for decolorization of azo dye (DR16) at microreactor using artificial neural network and genetic algorithm

The Fenton process is widely employed for decolorizing industrial wastewater. Therefore, it is imperative to construct a model for optimizing the operational parameters and estimating the efficiency of decolorization within this process. In this study, an artificial neural network (ANN) model was created based on experimental data provided by a previous researcher who examined the decolorization of Direct Red 16 dye (DR16) using a heterogeneous Fenton process within a microchannel reactor. This model was utilized to optimize and forecast the efficiency of decolorization in the Fenton process. The accuracy of the model was validated by comparing its outcomes with actual experimental data. To further improve the efficiency of decolorization, optimal operational parameters were ascertained utilizing the genetic algorithm method. The study revealed that as dye concentrations increased from 10 to 40 mg/l, decolorization efficiencies improved proportionately, peaking at 89.78 %. Optimal operational parameters for maximizing efficiency were identified as a feed flow rate of 1 ml/min, H2O2 concentration at 500 mg/l, Fe2+ concentration of 4 mg/l, and maintaining pH between 2.6 and 2.8. Insights derived from both experimental and model-generated data were used to analyze the impact of operational parameters on decolorization efficiency.

Synthesis and characterization of peanut shell-derived ferromagnetic activated carbon: application in the Fenton process for the degradation of methyl orange

The objective of the current work was to synthesize and characterize ferromagnetic activated carbon from peanut shells (PSs) and apply it for the degradation of methyl orange (MO) following the heterogeneous Fenton process. PSs were activated with phosphoric acid and potassium hydroxide at 1:1, 1:2, and 1:3 solid/liquid activation ratios and different concentrations (0.5, 1, and 1.5 M) and pyrolized at 500°C. Based on the iodine indexes, KOH-activated carbon adsorbents exhibited higher porosity than the H3PO4-activated adsorbents. KOH-activated carbon at a 1:3 activation ratio (iodine value 591 mg/g) was selected for magnetization using iron (II) ions and catalytic mineralization of MO dye. The ferromagnetic activated carbon (AC-PS@FeII) was characterized using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, and nitrogen-adsorption BET measurements. AC-PS@FeII contained ferromagnetite with a cubic spinel structure and a specific area of 181.96 m2·g–1. AC-PS@FeII degraded MO with a degradation efficiency of 99.22% at pH 2, 4 g/L of catalyst dosage, and a 50-min contact time. The results of recyclability tests, using distilled water, revealed a slight decrease in degradation capacity after four runs, indicating that the developed catalyst was appreciably stable. The hetero-Fenton catalyst from peanut shells could be an ideal catalyst for treating wastewater contaminated with dyes as a path toward a circular economy.

Hybrid treatment of textile wastewater through catalytic thermolysis and catalytic heterogeneous Fenton processes

Hybrid treatment of textile wastewater through catalytic thermolysis and catalytic heterogeneous Fenton processes

Polymer-Supported Heterogeneous Fenton Catalysts for the Environmental Remediation of Wastewater.

Materials based on polymer hydrogels have demonstrated potential as innovative Fenton catalysts for treating water. However, developing these polymer-supported catalysts with robust stability presents a significant challenge. This paper explores the development and application of polymer-supported heterogeneous Fenton catalysts for the environmental remediation of wastewater, emphasizing the enhancement of metal incorporation into catalysts for improved efficiency. The study begins with an introduction to the heterogeneous Fenton process and its relevance to wastewater treatment. It further delves into the specifics of polymer-supported heterogeneous Fenton catalysts, focusing on iron oxide, copper complexes/nanoparticles, and ruthenium as key components. The synthesis methods employed to prepare these catalysts are discussed, highlighting the innovative approaches to achieve substantial metal incorporation. Operational parameters such as catalyst dosage, pollutant concentration, and the effect of pH on the process efficiency are thoroughly examined. The catalytic performance is evaluated, providing insights into the effectiveness of these catalysts in degrading pollutants. Recent developments in the field are reviewed, showcasing advancements in catalyst design and application. The study also addresses the stability and reusability of polymer-supported heterogeneous Fenton catalysts, critical factors for their practical application in environmental remediation. Environmental applications are explored, demonstrating the potential of these catalysts in addressing various pollutants. The Conclusions offers future perspectives, underlining the ongoing challenges and opportunities in the field, and the importance of further research to enhance the efficacy and sustainability of polymer-supported heterogeneous Fenton catalysts for wastewater treatment.

Methylene blue treatment with zero-valent iron/pyrite/H2O2 system under static and continuous flow conditions: Reaction mechanism and toxicity evaluation

Laboratory batch and continuous flow studies, coupled with surface and toxicity analysis, were performed to evaluate methylene blue treatment by heterogeneous Fenton process using zero-valent iron (ZVI) and pyrite as co-catalyst. The use of pyrite in batch reactors significantly enhanced methylene blue treatment by the ZVI/H2O2 system because of improved iron redox cycling. The continuous-flow experiments revealed that the reactor performance increased in the order of: ZVI/H2O2 < pyrite/H2O2 < ZVI/pyrite/H2O2 under dynamic flow conditions. The methylene blue treatment by the ternary ZVI/pyrite/H2O2 system was described by an initial degradation of methylene blue with *OH radicals, followed by the adsorption and/or co-precipitation of degradation intermediates with some spherical particles. The surface analysis showed that these spherical particles formed, even at pH less than 4. The genotoxicity and cytotoxicity tests performed on mouse embryonic fibroblast (3 T3-L1) and human embryonic kidney (HEK293) cell lines showed that the Fenton treatment of methylene blue using the ZVI/pyrite/H2O2 system resulted in the formation of degradation species with much lower toxicity levels relative to methylene blue. Moreover, the Fenton degradation species of methylene blue significantly enhanced the metabolic activity of several bacterial strains, including E. coli ATCC 8739 and P. aeruginosa PAO1.

Optimizing levofloxacin decontamination in aquatic environment: Iron-modified biochar in heterogeneous Fenton processes with peroxide and persulfate

This study evaluates the effectiveness of iron-modified biochar (Fe-BC) in fixed-bed heterogeneous Fenton processes for levofloxacin (LFX) removal, a widely-used fluoroquinolone antibiotic. The objective is to optimize parameters such as pH, oxidants (H2O2 and S2O82−), and biochar forms (functionalized and raw) using factorial analysis of mixed data (FAMD) and response surface methodology (RSM). These optimizations identified the ideal conditions for maximal LFX removal. The most effective removal with Fe-BC occurred at 2.5 mM H2O2 and pH 7.5, while the optimal S2O82− conditions were 1.6 mM at pH 2.8. Both Fe-BC and raw biochar (RBC) showed the highest adsorption at pH 5.8. In adsorption-only, RBC and Fe-BC reduced LFX to 530 μg/L and 335 μg/L, respectively, in 60 min. The oxidation process further decreased LFX levels to between 8.9 μg/L and 0.1 μg/L using S2O82− and H2O2, respectively. The research expanded upon a kinetic model, incorporating the calculation of kinetic constants for both adsorption and oxidation processes, to deepen our understanding of the intricate degradation dynamics at play. Identifying by-products was crucial in elucidating degradation pathways. These findings are vital for environmental remediation, demonstrating the efficiency of Fe-BC in removing harmful antibiotics from water. This research highlights the potential of modified biochar in environmental clean-up, especially for water contaminated with antibiotics. The results emphasize the importance of optimizing treatment conditions for effective antibiotic removal, contributing valuable insights to the field of environmental remediation.

Green synthesis of iron nanoparticles from the baru (Dipteryx alata) endocarp extract for the efficient removal of rhodamine B and caffeine from water through the heterogeneous Fenton process

Abstract This study presents the first-time synthesis of iron nanoparticles (FeNPs) using an aqueous extract from the baru fruit endocarp (Dipteryx alata). Characterization through scanning electron microscopy and dynamic light scattering revealed spherical shapes with an average diameter of 419.2 nm. Fourier transform infrared spectroscopy identified phytochemicals from the baru fruit extract, acting as both reducing and stabilizing agents. X-ray diffraction confirmed the amorphous nature of the FeNPs. The Fenton-like catalytic efficiency of FeNPs was investigated for degrading rhodamine B (RhB) and caffeine. The impact of crucial parameters such as pH, H2O2 dosage, nanoparticles concentration, and temperature on the degradation process was assessed. At pH 3.0, with 1.0 g L−1 of FeNPs, 1% H2O2, and 45 °C, RhB and caffeine degradation reached 99.14 and 92.01%, respectively. The catalytic reaction kinetics followed a pseudo-first-order model for caffeine and a pseudo-second-order model for RhB. Phytotoxicity studies on Cucumis sativus confirmed the non-toxic nature of the degraded products of RhB and caffeine. These findings highlight the potential of FeNPs synthesized from the baru endocarp extract as a catalyst for removing organic pollutants, suggesting promising applications in environmental remediation and related fields.

Olive mill waste bio-based catalyst application in advanced oxidation processes for wastewater treatment

This study explores the physicochemical capacities of solid wastes from olive oil mills (olive stone, OS, and olive pomace, OP), in obtaining catalysts to be applied in heterogeneous Fenton and persulfate processes. Through physicochemical treatments and the impregnation of iron by hydrothermal deposition and wetness impregnation (WI) different catalysts were produced, tested and characterized. The olive mill wastewater (OMW) studied in this work is a synthetic solution with five phenolic compounds to mimic the real effluent. The removal efficiency of phenolic acids and organic load (COD) present in this type of effluent was evaluated. In the treatment of synthetic wastewater, almost 100% COD was removed using OS and OP-FeWI as catalysts in the heterogeneous Fenton process. In the sulfate radical-based reaction, the 3,4–Dihydroxybenzoic acid was slightly more degradable than other phenolic acids which confirms the selectivity of sulfate radicals. The materials subject to thermal processes revealed an interesting adsorption capacity. This procedure not only reduces the environmental impact of OMW, but also promotes the implementation of new circular economy approaches.

Treatment of membrane-concentrated landfill leachate by heterogeneous chemical and electrical Fenton processes with Iron-loaded granular activated carbon catalysts

The composition of the membrane-concentrated landfill leachate (MCLL) is complex with a high concentration of organic matter and inorganic ions. In this study, a chemical and an electro-Fenton system were constructed to treat MCLL from a mature landfill using granular activated carbon loaded with iron oxides as heterogeneous Fenton catalysts. In the chemical Fenton treatment optimized by orthogonal experiments, the COD and colour removal rates were 93.9% and 80.2%. For the electro-Fenton system, the best COD, colour, and TN removal rates of MCLL reached 95.7%, 99%, and 94.9% with an energy consumption (EC) of 0.098 kWh·(g COD)−1 under the condition of pH 6, applied voltage 8 V, the reaction time 4 h, and the catalyst dosage 16.67 g L−1. Various spectral analyses confirmed that refractory organic matter and toxic substances in the MCLL were effectively degraded. The synergistic effect study of the factors in chemical Fenton indicated that as far as the effect on COD removal is concerned, heterogeneous Fenton system > catalyst adsorption > activated carbon/H2O2 system > activated carbon adsorption. The results of free radical quenching experiments illustrate that a large amount of ·OH was produced in the chemical heterogeneous Fenton system, while both ·OH and active chlorine play important roles in the removal of pollutants for the electro-Fenton system. MCLL can be disposed of costly and effectively by chemical and electrical Fenton processes with Iron-loaded granular activated carbon catalysts.

Heterogeneous Fenton Degradation of Batik Wastewater using Natural Pyrite

Heterogeneous Fenton processes with solid natural pyrite catalyst have gained attention for wastewater treatment. The improvement of degradation efficiency of natural pyrite is specific and therefore, it is still a challenging issue. This study was aimed to investigate the performance of Indonesian natural pyrite, without any purification, to treat the real wastewater obtained from batik home industry. To address this issue, several experiment variables such as pre-reaction between pyrite and hydrogen peroxide, hydrogen peroxide concentration, and pH were investigated. COD removal has been found to increase in a slightly acid condition (4.5 to 5.65) and inhibited at pHs of 8 and above (10). The results showed the presence of hydrogen peroxide was indeed greatly influence the wastewater degradation and the solution pH did not significantly change the wastewater degradation in the range of 3 and less than 8. Moreover, the pre-reaction period was found as the important part to initiate the degradation process. The optimum degradation efficiency was obtained by providing the pre-reaction time of 20 min with the addition of 326 mmol/L of H2O2 in the system and the mixture was reacted for 30 min at room temperature and real wastewater pH. Based on results observed in this study, it can be concluded that the batik wastewater can be degraded by natural pyrite up to 84% under reaction conditions studied. This finding offers great opportunity to further investigate and develop the heterogeneous Fenton process for real applications in industry.