• Bulletin of the Korean Chemical Society
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• v.27 no.4
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• pp.489-494
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• 2006

Goethite, hematite, magnetite and synthesized iron oxide are used as catalysts for Fenton-type oxidation of phenol. The synthesized iron oxides were characterized by X-ray diffraction (XRD), BET, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR). The catalytic activity of these materials is classified according to the observed rate of phenol oxidation. The effectiveness of the catalysts followed the sequence: ferrous ion > synthesized iron oxide >> magnetite hematite > goethite. According to these results, the most effective iron oxide catalyst had the structure similar to natural hematite. The surface oxidation state of the catalyst was between magnetite and hematite (+2.5 ~ +3.0). Phenol degraded completely in 40 min at neutral pH (pH = 7). Soluble ferric and ferrous ions were not detected in the filtrate from Fenton reaction solution by AAS. The formation of hydroxyl radicals was confirmed by EPR.

• Journal of Environmental Health Sciences
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• v.35 no.3
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• pp.201-208
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• 2009

Oxidation of phenol in aqueous media by electro-Fenton process using Ru-Sn-Sb/graphite electrode has been studied. Hydrogen peroxide was electrically generated by reaction of dissolved oxygen in acidic solutions containing supporting electrolyte and $Fe^{2+}$ was added in aqueous media. Phenol degradation experiments were performed in the presence of electrolyte media at pH 3. Effect of operating parameters such as current, electrolyte type (NaCl, KCl and $Na_2SO_4$) and concentration, $Fe^{2+}$ concentration, air flow rate and phenol concentration were investigated to find the best experimental conditions for achieving overall phenol removal. Results showed that current of 2 A, NaCl electrolyte concentration of 2g/l, 0.5M concentration of $Fe^{2+}$, air flow rate of 1l/min were the best conditions for mineralization of the phenol by electro-Fenton.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.184-190
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• 2005

A new VFAs production process from sewage sludge using Fenton's oxidation was investigated. Optimum concentrations of $H_2O_\;and\;Fe^{2+}$ as well as optimum reaction temperature for VFAs production were studied. In the presence of $Fe^{2+}$ as catalyst, the VFAs formation rate increased about 4 times compared to $H_2O_2$ oxidation process without $Fe^{2+}$. Optimum concentrations of $H_2O_2$ and $Fe^{2+}$ were 0.62 M and 0.007 M, respectively. VFAs formation reaction proceeded rapidly within 1 min and VFAs formed degraded partly to acetic acid and $CO_2$, which exhibited series reaction characteristics. Based on the economic aspect, reaction temperature of $25^{\circ}C$ and 10 min of reaction time were thought to be proper reaction conditions. The effect of initial pH in the range of $3{\sim}6.3$ on the VFAs formation was not observed.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.1
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• pp.109-117
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• 2010

In the present study, the degradation characteristics of Lindane by Advanced Oxidation Processes(UV/$H_2O_2$, Photo-Fenton process) were studied. The degradation efficiency of Lindane in aqueous solution was investigated at various initial pH values, Fenton's reagent concentrations and initial concentrations of Lindane. GC-ECD was used to analyze lindane. Lindane has not been degraded without application of AOPs over two hours. But, approximately 5% of lindane was degraded with UV or $H_2O_2$ alone. Lindane with UV/$H_2O_2$ process showed approximately 7% higher removal efficiency than $H_2O_2$ process. In the UV/$H_2O_2$ process, the pH values did not affect the removal efficiency. The optimal mole ratio of $H_2O_2/Fe^{2+}$ for lindane degradation is about 1.0 in Photo-Fenton process. Also, the experimental results showed that lindane removal efficiency increased with the decrease of initial concentration of lindane. Under the same conditions, the order lindane of removal efficiency is as following : Photo-Fenton process > UV/$H_2O_2$ process > $H_2O_2$ process. In addition, intermediate products were identified by GC-MS techniques. Than PCCH(Pentachlorocyclohexene) was identified as a reaction intermediate of the Photo-Fenton process.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.E1
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• pp.16-28
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• 2007

An improved method was developed to determine gas-phase hydrogen peroxide($H_2O_2$) and organic hydro-peroxides (ROOH) in real-time, The analytical system for $H_2O_2$ is based on formation of hydroxybenzoic acid (OHBA), a strong fluorescent compound. OHBA is formed by a sequence of reactions, photoreduction of Fe(III)-EDTA to Fe(II)-EDTA, the Fenton reaction of Fe(II)-EDTA with $H_2O_2$, and hydroxylation of benzoic acid. By use of this analytical method rather than a previous similar method, Fenton reaction time was reduced from 2 min. to 30s. Air samples were collected by a surfaceless inlet to prevent inlet line losses. With a special arrangement of the sampling apparatus, sample delivery time was drastically reduced from ${\sim}5\;min\;to\;{\sim}20\;s$. The automated system was found to be sensitive, capable of continuous monitoring, and affordable to operate. A comparison of this method with a well-established one showed an excellent linear correlation, validating applicability of this technique to $H_2O_2$ determination. The system was applied to field measurements conducted during summertime of 2004 in Gwangju, South Korea. $H_2O_2$ was found to be a predominant species of peroxides. The diurnal variation of $H_2O_2$ displayed the maximum in early afternoon and the broad minimum throughout night. $H_2O_2$ was correlated positively with ozone, photochemical age, and temperature, however, negatively with $NO_x$ and relative humidity.

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.47-53
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• 2004

Feasibility of electrokinetic process combined with Fenton-like reaction was investigated for the removal of phenanthrene from contaminated soil. Transport of hydrogen peroxide by electroosmosis and decomposition of phenanthrene by Fenton-like reaction were observed in a model system. Electrical potential gradient and electroosmotic flow (EOF) at 10 mA were higher than those at 5 mA. High accumulated EOF resulted in high removal efficiency of phenanthrene because the large amount of hydrogen peroxide was transfered through the soil. Removal efficiency of phenanthrene by water washing was 8.5% for 7 days. The highest removal efficiency including phenanthrene decomposition was 95.6% for 14 days. After the operation, soil samples with removal efficiency of 95.6% showed low concentrations of phenanthrene and its intermediates. From this result, it was presumed that phenanthrene was decomposed to small molecules or mineralized to water and carbon dioxide due to continuous supply of hydrogen peroxide by electroosmotic flow.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.6
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• pp.340-348
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• 2015

Removal efficiency of PCBs in contaminated marine sediments treated by Fenton-like oxidation combined with surfactant was investigated in this research in order to achieve remediation of PCBs. A washing treatment using various concentrations of hydrogen peroxide (1% and 15%) and surfactants (Triton X-100, Tween 60 and Tween 80) was evaluated at various conditions in laboratory scale experiments. The mean removal efficiencies of tPCBs varied from 24.1 to 46.7% in the sediments for 1 hour duration of the treatments. The concentration of tPCBs in contaminated marine sediments after the simultaneous treatment with hydrogen peroxide and surfactant satisfied the domestic environmental standards for the beneficial use of sediments. When suitable surfactant was used for Fenton-like oxidation, the removal efficiency of tPCBs at low concentration of hydrogen peroxide was similar to that at high hydrogen peroxide concentration. Thus the efficient removal of PCBs in contaminated marine sediments could be achieved through treatment with Fenton-like oxidation combined with surfactant washing.

• Advances in environmental research
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• v.10 no.1
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• pp.59-86
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• 2021

Landfilling is the most commonly adopted method for a large quantity of waste disposal. But, the main concern related to landfills is the generation of leachate. The leachate is high strength wastewater that is usually characterized by the presence of high molecular recalcitrant organics. Several conventional methods are adopted for leachate treatment. However, these methods are only suitable for young leachate, having high biodegradability and low toxicity levels. The mature and stabilized leachate needs advanced technologies for its effective treatment. Advanced oxidation processes (AOPs) are very suitable for such complex wastewater treatment as reported in the literature. After going through the literature survey, it can be concluded that Fenton-based approaches are effective for the treatment of various high/low strength wastewaters treatment. The applications of the Fenton-based approaches are widely adopted and well recognized due to their simplicity, cost-effectiveness, and reliability for the reduction of high chemical oxygen demand (COD) as reported in several studies. Besides, the process is relatively economical due to fewer chemical, non-sophisticated instruments, and low energy requirements. In this review, the conventional and advanced Fenton's approaches are explained with their detailed reaction mechanisms and applications for landfill leachate treatment. The effect of influencing factors like pH, the dosage of chemicals, nature of reaction matrix, and reagent ratio on the treatment efficiencies are also emphasized. Furthermore, the discussion regarding the reduction of chemical oxygen demand (COD) and color, increase in biodegradability, removal of humic acids from leachate, combined processes, and the pre/post-treatment options are highlighted. The scope of future studies is summarized to attain sustainable solutions for restrictions associated with these methods for effective leachate treatment.

• Journal of Soil and Groundwater Environment
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• v.7 no.3
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• pp.95-102
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• 2002

Manganese oxide/ hydrogen peroxide($MnO_2$/${H_2}{O_2}$) reactions were investigated as an alternative to Fenton-like reaction to reduce chlorinated organic compounds in groundwater This system showed high degradation of CT with low ${H_2}{O_2}$concentration($\leq$294mM) at neutral condition, and CT degradation increased with increasing pH values. The rate of CT degradation was not so much dependent on increase in $MnO_2$concentration since increase in production of oxygen during the reaction obstructed reaction of ${H_2}{O_2}$ on the surface of $MnO_2$. These results show that $MnO_2$catalyzed Ponton-like reaction could be a potential alternative method for treating chlorinated organic compounds in groundwater.

• Journal of Soil and Groundwater Environment
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• v.11 no.1
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• pp.7-13
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• 2006

The effects of electrolytes were investigated on the removal efficiency when several different electrolytes were used to change the electrode reaction in an electrokinetic (EK)-Fenton process to remediate phenanthrene-contaminated soil. Electrical potential gradient decreased initially due to the ion entrance into soil and then increased due to the ion extraction from soil under the electric field. Accumulated electroosmotic flow was $NaCl>KH_2PO_4>MgSO_4$ at the same concentration because the ionic strength of $MgSO_4$ was the highest and $Mg(OH)_2$ formed near the cathode reservoir plugged up soil pore to inhibit water flow. When hydrogen peroxide was contained in electrolyte solution, removal efficiency increased by Fenton reaction. When NaCl was used as an electrolyte compound, chlorine ($Cl_2$) was generated at the anode and dissolved to form hypochlorous acid (HClO), which increased phenanthrene removal. Therefore, the electrode reaction of electrolyte in the anode reservoir as well as its transport into soil should be considered to improve removal efficiency of EK-Fenton process.