Tesis sobre el tema "Fenton-like reaction"

This project focussed on an in-depth evaluation of an established methodology that uses dimethyl sulfoxide (DMSO) as a reactive solvent with a profluorescent nitroxide (PFN) to detect and quantify particulate matter-derived ROS (Reactive Oxygen Species). Additionally, a novel approach which utilized cyclic sulfoxide tetrahydrothiophene-1-oxide (THTO) as the reactive solvent was investigated. The reactions of these sulfoxides with ROS generated from multiple sources in the presence of nitroxide radical scavengers were investigated. The results of these experiments show that nitroxides can display much broader reactivity than the simple radical scavenging processes that have previously been accepted.

Thesis (Ph. D.)--University of Maryland, College Park, 2005.
Thesis research directed by: Chemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

As an essential resource for life and most human activities, water resources protection have become one of the major focuses of scientific community, especially the increasing occurrence of emerging pollutants which have its origin in commonly used pharmaceuticals, personal care products, pesticides and some other anthropogenic origin compounds. Fenton and photo-Fenton are advanced oxidation processes (AOPs) that have been widely proved on the removal of these compounds, but they are conventionally applied at acidic pH, below 3.0, because these processes involve the use of iron (II) salts, which are not soluble above. Also, the acidic effluents must be neutralized and high amounts of iron sludge are formed in the process. Current research in the field tries to solve this drawback by focusing in two possible solutions: the use of chelating agents to keep iron soluble at circumneutral pH or the use of heterogeneous catalysts containing iron that can be easily removed and reused after its application. This work is focused on the study, application and improvement of alginate-based heterogeneous catalysts for conducting photo-Fenton reactions at circumneutral pH. Initially, the preparation process of the conventionally used Fe(III)/alginate catalyst was optimized by evaluating the effect of the parameters involved on its synthesis. Then, the synthetized catalyst was applied to the abatement of antibiotic sulfamethoxazole (SMX), which was used as reference compound. The reaction mechanism of alginate-based catalysts was proposed according to the results obtained. Also, a deep study about catalyst stability revealed a high dependence with water’s pH. Fe(III)/alginate catalyst proved to release iron when sample’s pH was below alginate’s pKa. Also, due to its organic nature, a significant HO· scavenging effect of alginate itself was observed, which reduced the effective amount of hydroxyl radicals available for the oxidation of the target compound. Fe(III)/alginate was also tested for disinfection by adjusting the conditions to ensure a minimal iron release. Thus, the contribution of homogeneous reaction was significantly avoided. The catalyst proved being able to be used for disinfection of waters with low organic loads. In order to improve the Fe(III)/alginate catalyst, some modifications were applied. The first one was the addition of a dehydration stage after its synthesis. The resulting catalyst was tested on the removal of SMX and had a similar effectiveness than the conventionally used Fe(III)/alginate but with a significantly lower iron release, which confirmed its improved stability. This more stable catalyst was also modified by including TiO2, zero valent iron (ZVI) particles or cerium on its structure with the aim of, not only increase its stability, but its effectiveness. The TiO2 catalyst proved to increase the effectiveness of the overall removal of SMX while the other two modifications did not. Red volcanic rocks, iron shavings from metallurgical industry, a commercial Fe/Mn/O catalyst and a self-synthetized Fe/Ce/O catalyst were also tested as heterogeneous catalysts for Fenton and photo-Fenton at acidic and neutral pH. These catalysts were selected as inorganic-based ones and were compared to the Fe(III)/alginate dehydrated catalyst when applied to photo- Fenton at neutral pH. Results proved that only volcanic rocks had a significant activity when applied for photo-Fenton at neutral pH, but the effectiveness on the removal of SMX was low in comparison to the alginate-based catalyst. All other catalysts presented too low activity or major drawbacks that made them not suitable for water purification through Fenton-like and photo-Fenton-like processes.
Los procesos Fenton y foto-Fenton son procesos de oxidación avanzada (POA) que se basan en la descomposición del peróxido de hidrógeno catalizada por sales de hierro (II), produciendo radicales hidroxilo que son altamente oxidantes. El segundo además incorpora la irradiación con luz ultravioleta en el rango A, cosa que permite acelerar el proceso debido a la recuperación del hierro (II), que durante la reacción principal pasa a hierro (III). Estos procesos se suelen llevar a cabo a pH ácido (pH<3) debido a la baja solubilidad y la poca actividad de las especies de hierro a pH cercanos a la neutralidad. Este trabajo se centra en el estudio y aplicación de un catalizador heterogéneo de Fe/alginato formado gracias a la propiedad del alginato de formar geles sólidos en presencia de cationes di y trivalentes. En este caso, el Fe(III) actúan como enlace entre cadenas de alginato. Inicialmente se estudió el proceso de fabricación de este catalizador y se propuso un proceso estándar optimizado para su uso aplicado a la reacción foto-Fenton. Posteriormente se evaluó su aplicación a la eliminación del antibiótico sulfametoxazol y a la desinfección de bacterias Escherichia Coli. Basándose en los resultados obtenidos se propuso un mecanismo de reacción que además explicaba la inestabilidad observada experimentalmente que producía la liberación de hierro dependiendo del pH del medio de reacción, lo que desencadenaba la vía de reacción homogénea. Con la intención de mejorar la estabilidad del catalizador, se modificó el proceso de síntesis añadiendo una etapa de deshidratación controlada al final del proceso. Los resultados en su prueba para la reacción foto-Fenton aplicada a la eliminación de sulfametoxazol mostraron que el rendimiento no empeoraba pero mejoraba significativamente su estabilidad. Para aumentar su eficiencia se probó incorporar cerio, partículas de hierro monovalente y TiO2. Los resultados mostraron que solo el catalizador modificado con TiO2 mejoraba el rendimiento global de la reacción. Por último, se probaron otros catalizadores heterogéneos (piedras volcánicas, Fe/Ce/O, Fe/Mn/O, limaduras de hierro) aplicados a la reacción foto-Fenton. Solo las piedras volcánicas mostraron actividad catalítica y ésta, en comparación con la del catalizador de alginato fue baja.

L’oxyde de graphène (GO) et le δ-FeOOH, réputés pour leur biocompatibilité, leurs grandes surfaces spécifiques et leur facilité de fonctionnalisation, présentent un potentiel prometteur pour des applications biomédicales, notamment dans la lutte contre les infections bactériennes et le traitement du cancer.Cette thèse a exploré la synthèse, la fonctionnalisation et les applications de ces matériaux bidimensionnels (2D). Le premier projet a consisté à fonctionnaliser le GO avec des peptides antimicrobiens (AMPs) en utilisant la chimie Click pour améliorer son activité antibactérienne, une stratégie utilisant des polymères ramifiés s’étant avérée particulièrement efficace pour améliorer l’activité antibactérienne. Le deuxième projet a tenté d'accroître l’efficacité antibactérienne du GO en liant à sa structure des composés d'ammonium quaternaire (QACs). Cependant, cette approche n’a pas réussi à surpasser l’efficacité des composants individuels. Le troisième projet a exploré l’utilisation du δ-FeOOH et de ses dérivés dans des réactions de type Fenton pour des thérapies potentielles contre le cancer. Globalement, la recherche menée dans cette Thèse souligne la nécessité d'optimiser les stratégies de fonctionnalisation afin d'équilibrer la biocompatibilité et l’efficacité, tout en explorant les capacités des nouveaux matériaux ferreux 2D dans les applications biomédicales
Graphene oxide (GO) and δ-FeOOH, notable for their biocompatibility, high surface area, and ease of functionalization, show promising potential for biomedical applications, specifically in combating bacterial infections and treating cancer.This thesis explored the synthesis, functionalization, and applications of these two-dimensional (2D) materials. The first project concerned functionalizing GO with antimicrobial peptides (AMPs) using the Click chemistry to enhance its antibacterial activity, with one strategy using branched polymers proving to be particularly effective in enhancing the antibacterial efficacy. The second project attempted to improve the antibacterial effectiveness of GO by attaching to its structure quaternary ammonium compounds (QACs). However, this approach failed to exceed the efficacy of the single individual components. The third project explored the use of δ-FeOOH and its derivatives in Fentonlike reactions for potential cancer therapies. Overall, the research explored in this Thesis emphasizes the need to optimize the functionalization strategies to balance the biocompatibility and the efficiency, while also exploring the capabilities of novel iron-based 2D materials in biomedical application

碩士
國立屏東科技大學
環境工程與科學系
90
In situ Fenton-like oxidation injects hydrogen peroxide to the subsurface to promote the production of hydroxyl radicals and oxidation of organic contaminants. The production of hydroxyl radicals, though the catalysis of H2O2 by iron oxyhyroxyl minerals, is the key of Fenton-like reaction. In this research, the rate and yield of hydroxyl radicals produce during the Fenton-like oxidation catalyzed by different iron oxyhydroxyl materials was quantify. Nitrobenzene was used as a chemical probe for Fenton-like reaction. Equations and constants derived from reference papers were used to calculate the rate and yield of hydroxyl radicals production. The results from TEM, XRD, and chemical analysis indicate that the type of iron oxyhydroxyl minerals in test media A and B was goethite, while that in medium C was mainly ferrihydrite. The production rate of hydroxyl radicals did not increased proportional to the H2O2 depletion rates at low H2O2 doses. The highest hydroxyl radical production rate was 1.2×10-6 M/min at H2O2 of 0.01％. The production rate of hydroxyl radicals decreased when H2O2 concentrations were increased from 0.01％ to 0.5％, and then rebound slightly when the H2O2 concentration was farther increased. There were high hydroxyl radicals produce in low H2O2 concentration (0.01％), in other words, low H2O2 concentration has high useful efficiency each unit. Hence, the yield of hydroxyl radicals increased with nitrobenzene concentration when different iron minerals catalysis.

碩士
國立屏東科技大學
環境工程與科學系
91
The contamination of groundwater and subsurface soils still poses a significant problem even after two decades of research and implementation. In situ Fenton-like oxidation injects hydrogen peroxide to produce hydroxyl (HO.) radicals to mineralize organic contaminants. The hydroxyl radical is the major oxidant in this process and each contaminant has it own reaction rate constant (KHO.,P) with HO. radicals. In this research, the Fenton-like oxidation catalyzed by synthetic goethite and an aquifer sand containing natural goethite was conducted. Equations and constants derived from reference papers were used to calculate the HO. production and KHO.,P for several chlorinated ethylene contaminants. The results showed that the yield of HO. radicals was in the order of 10-12 mM for goethite, and irrelevant to the initial H2O2 doses. However, higher H2O2 doses were required in aquifer sand to produce the similar quantity of HO. radicals. The molar transformation ratios of H2O2 to HO. radicals for different iron oxides ranged from 10-15 to 10-13. The yield and production rate of HO. radicals would be better than the first order decay constant of H2O2 for evaluating the catalytic capability of iron oxides during Fenton-like reaction. The H2O2 dose and characteristics of goethite did not affect the KHO.,P values of chlorinated ethylene compounds. The KHO.,P values for chlorinated ethylene were in the order of PCE＞TCE＞Trans 1,2-DCE＞1,1-DCE＞ Cis 1,2-DCE, and was found to be proportional to the octanol-water partition coefficient (Kow) of chlorinated ethylene contaminants.

碩士
國立中央大學
環境工程研究所
106
The textile industry in Taiwan has been developed over 50 years, and it created high economic value for many years. Textiles plays an important role in apparel industry, because of the ability for moving towards high value-added products. Unfortunately, human appealing and wear glamorous clothes have ended up causing harm to the environment. The textile industry is one of the most pollutants releasing industries of the world. Most of primary and secondary treatment processes can deal with wastewaters. However, textile dyeing wastewater which containing versatile components, including many aerosols, high chroma, high BOD and COD, it lead difficult to remove textile dyeing wastewater only by use primary and secondary treatment. Therefore, it’s important to create a novel way to treat textile dyeing wastewater. In this study we use Fenton-like reaction to create hydroxyl radicals which are among the strongest oxidizing agents and are able to decolourise a wide range of dyes. For Fenton-like reactions we selected Chungli laterite as the iron source, which has been recognized that Fe(OH)2+ can lead to the formation of hydroxyl radical (HO∙) and Fe(Ⅱ) through a ligand-to-metal charge transfer pathway. Our investigation reveals that dye in water not only decolourisation by Fenton-like reaction but also adsorption by laterite. Meanwhile, it was observed that dyes adsorped by laterite result in low Fenton-like reaction efficiency. Additional experiments were carried out using calcination laterite by 400 degrees Celsius and 700 degrees Celsius, where Fenton-like reactions were characterized with different pH, H2O2 dosage and reaction time. Results demonstrated that the 400 degrees Celsius calcination laterite was the most effective matrix for Fenton-like reaction. It’s also show that the most effective to dyes decolourise was crystal violet. We also pressed laterite as a cake for the re-use of Fenton-like reaction, and the effective to decolourise crystal violet is still more than 75% after four times reused. Our study may offer the possibility of the great potential applications of the calcination laterite in wastewater treatment areas especially for those containing compounds which are not easy to remove by traditional treatment processes.

碩士
嘉南藥理科技大學
環境工程與科學系暨研究所
91
This research was to evaluate the treatment efficiency and formation of nitrogen-containing compounds from Fenton-like reaction of acrylonitrile (AN) in aqueous solution. HPLC, TC, IC and TKN were used for the evaluation.The effects of pH value of solution, initial concentration of hydrogen peroxide and ferric ions were examined. The efficiency of Fenton-like process was measured by the decomposition of acrylonitrile, removal of dissolved organic carbon (DOC). In addition, formation and variation of organic nitrogen, ammonia nitrogen, nitrite and nitrate ions during the reaction were also detected in this study. In general, it is an effective method to remove acrylonitrile from the aqueous solution using Fenton-like method. In this study, after 60 minutes Fenton-like process treatment, the decomposition of acrylonitrile at the condition of pH 2.5 was above 100%. On the other hand, acrylonitrile could not be decomposed completely at pH 3. The result also showed that the removal efficiencies of AN and DOC increased with increasing of hydrogen peroxide. The same phenomenon was observed when the hydrogen peroxide concentration was varied. The highest removal efficiency of 100% and 55% for AN and DOC, respectively, was obtained in this study. On the study of nitrogen mass balance, immediately after the Fenton-like reagent addition, NO2－ rose rapidly up to a peak and followed by a slow decline. The similar phenomenon of NH4+ was observed in this study. The concentration of NO3－ increased with reaction time and then remained approximately constant. Formation of NO2－ and NO3－ increased with increasing of Fenton-like reagent dosage. Visible gas evolution from the reaction vessels suggested gaseous byproducts. Nitrogen gas yields were calculated from the nitrogen balance results. Nitrogen gas production accounted for about 90&# 12316;94% of nitrogen in AN. The ideal-gas law was used to calculate the volume of nitrogen gas. The results showed that 40〜44mL of nitrogen gas was produced during 1 hour Fenton-like reaction. The kinetic of the decompositions of hydrogen peroxide and DOC followed the pseudo-first order reaction, and the highest observed reaction constant value of 0.070 min-1 and 0.096 min-1, respectively, was obtained in this study.

碩士
國立屏東科技大學
環境工程與科學系所
96
The traditional Fenton oxidation method, when operated in the neutral pH range, will produce a large amount of sludge or sediments and clog aquifers. There are many new catalysts tested nowadays to replace the Fe(II) ions. These modified processes are one type of Fenton-like oxidation. The purpose of this study was to explore an organic acid B and Fe (III) complex as a new catalyst for Fenton-like reaction to (1) understand the effectiveness of Fe(III)-organic acid B complex in Fenton-like reaction, and to (2) develop a more friendly remediation technology for contaminated sites. This study used batch reaction systems to evaluate the catalytic efficiency of the Fe(III)-organic acid B complex. The results revealed some (about 0.12 ~ 0.17 mg) of the added benzene (C0=0.4 mg) was adsorbed by the Fe(III)-organic acid B. The better degradation of benzene was found by increasing the concentration of organic acid B at 7-370 mg/L. The degradation of benzene increased to 50%. However, when the concentration of organic acid B in the solution was further increased to 478.3- 782.6 mg / L , it will inhibit the Fenton-like reaction. The best degradation efficiency for benzene removal occurred at Fe(III)-organic acid B complex weight ratio of 1:13.The oxidation of benzene at 0.8 mg by the Fenton-like reaction catalyzed by Fe(III)-organic acid B complex was about 0.46 mg. More benzene removal (up to 0.69 mg) was found at lower Fe (III)-organic acid B complex but the same initial benzene concentration and H2O2 dose. Also, at low concentrations of Fe(III)-organic acid B complex (w/w ratio=1:13 and organic acid B = 50 mg / L), the removal of benzene by 59 mM H2O2 was as high as 80 to 90 %, which was 40 to 60 percent better than that of 588 mM H2O2 . In addition, at 59 mM H202 and Fe(III)-organic acid B complex ratio= 1:13 and 1:35 (w / w) , the Fenton-like oxidation of benzene (0.8 mg) last four hours. The Fenton-like reaction catalyzed by iron minerals usually stops within 1 hr, and the data in this study showed a potential advantage in the field. The kinetic result showed that the first order reaction rate constant k for Fenton-like reaction of benzene using the developed catalyst at Fe(III): organic acid B weight ratio=1:13 and benzene concentration = 0.1 mg was 0.3539 (1/min). At higher initial concentration of benzene (0.8 mg) , the k increased to 0.5026 (1/min). Thus, it appeared that the initial concentration of benzene affect the Fenton-like removal efficiency as well as the reaction constant.

碩士
國立屏東科技大學
環境工程與科學系
93
NAPL-type contaminats are very diffcult to be removed from a contaminated groundwater site. The heterogeneity of aquifers usually results in NAPL droplets of different sizes trapped in aquifers. In this reserch, Fenton-like oxidations cataylzed by synthetic goethite for three DNAPLs of chlorinated ethylene and three LNAPLs of aromatic compounds were performed to evaluate the reaction constants (KHO.,P) between hydroxyl radicals and DNAPLs of chlorinated ethylene with with different droplet sizes. The oxdation efficiencies of different NAPL compounds were compared . The result showed that the soluble phase of contaminants was oxidized more effectively than the NAPLs, and so are the KHO.,P values for chlorinated ethylene and aromatics. The initial H2O2 dose didn’t affect either oxidation efficiency or the reaction constant. The droplet size of chlorinated DNAPLs didn’t significantly affect the oxidation efficiency. The KHO.,P for PCE DNAPLs seems to increase slightly with the total surface area of droplets, but the others were not so obvious. Because the aromatic group have more π-bonds than the chlorinated ethylenes, the aromatic compounds are better than the chlorinated ethylenes in the oxidation efficiency and the KHO.,P both for the soluble and NAPL phase. Although the oxidation efficiency of NAPLs was 10~20% less than that of the soluble form for all the six compounds, such a reduction would pose a more negative impact on the oxidation of cis 1,2-DCE and benzene due to their low reactivity to the hydroxyl radicals.

碩士
國立中興大學
環境工程學系所
106
In view of technological advances, people start to use disposable Hand warmer. However, it leads to an increasing of iron-containing waste. Though hand warmer is harmless to the environment, it sill needs to be recycled. Therefore, it is supposed to recycle and reuse the iron-containing waste. This study bases on advanced oxidation treatment technology. Heterogeneous Fenton reaction can treat Alachlor of high toxicity endocrine disrupting chemicals. The catalyst is divided into core-shell zero-valent iron and Hand warmer recovery iron different treatment methods. Hand warmer is utilized to become Fe@Fe2O3 core shell nano-zero-valent iron, which compare with FeCl3•6H2O. Another direct use Hand warmer waste iron, which is divided into untreated iron(HWW), hydrochloric acid pickled iron(AHWW) and sodium borohydride reduced iron(RHWW). In this study explored Fenton-like reaction different treatment conditions (Amount of catalyst, concentration of oxidant, concentration of reducing agent, pH, etc.) on the degradation of Alachlor. The results show (1) Core-shell zero-valent iron optimal conditions was 0.1g/L catalyst , 2mM H2O2 and 0.3mM AA. Alachlor removal rate of Fe@Fe2O3 and R-Fe@Fe2O3 were 99.84% and 93.64%. The system is not affected by competitive ions and catalyst has reusability. (2) The AHWW of use directly Hand warmer waste iron is degradation of Alachlor better than the HWW and RHWW. The optimal conditions was 0.4 g/L catalyst , 2 mM H2O2 and 0.4 mM AA. The AHWW removal rate of Alachlor was 66.22% in the 60 min. The studies demonstrated that Hand warmer waste iron might be an economy and feasible way to removed pollutants for Alachlor.

碩士
國立屏東科技大學
環境工程與科學系所
97
In this study, we treated the contaminated sediments by Fenton-like oxidation. Adding nitrobenzene (NB) as indicator of semi-volatile pollutants. The sediments from Yanshuigang river, Houjin river, Niujiaowan river, Longjing river and Wuluo river were tested to represent samples from industrial , residential and husbandry areas. This study focused on the adsorption of NB in the river sediments, and the role of organic matters before and after Fenton-like oxidation. The oxidation parameters and results were expected to help the evaluation of treating different types of contaminanted river sediments by Fenton-like technology. The results showed after oxidation (1% H2O2, 5 times), NB adsorption in the river sediments was reduced up to 17.8%, large amounts of sediment organic matters were released to the water phase, which may reduce adsorption NB in the river sediments. The O.C. of sediment could enhance the efficiency. The highest removal rate of NB is the sediments collected from Yanshuigang river (98 %), followed by Houjin river (82 %) > Wuluo river (67 %) > Longjing river (64 %) > Niujiaowan river (27 %). Although a great quantity of organic pollutants could be sorbed to high contents of sediment organic matters in Yanshuigang river, but the results showed that Fenton-like oxidation would be promoted by sediment organic matters.

碩士
國立屏東科技大學
環境工程與科學系所
96
The catalyst used for traditional Fenton oxidation process is the ferrous ion form under acidic solution pHs. However, during the Fenton reaction, Fe hydroox precipitates form and the oxidation efficiency is significantly reduce. Also the Fenton reaction must be carried out under the acidic environment so it is not feasible for the soil and groundwater remediation. One of the Fenton-like process (also called the modified Fenton reaction) is the use of organic acid or chelate complexed with Fe (II) or Fe (III) as a new catalyst. A Fe (III)-organic acid A complex (named the Fe (III) complex A), developed in our previous batch study, has shown that the Fe (III) complex A can keep the iron ion exist stably in the solution and therefore maintain the oxidation efficiency. This study continue to test the transport and catalysis of Fenton-like oxidation of benzene and toluene by the developed Fe (III) complex A in soil columns, using the optimum Fenton-like reaction condition found previously. First the results in batch experiments found that more toluene was removed by the Fenton-like oxidation catalyzed by Fe (III) complex A at 0.5% and 1% H2O2 than benzene. More toulene degradation ocuurred by the repeated H2O2 dose. The results in the column tests revealed that the Fe (III) complex A solution at Fe (III) : organic acid (A) molar ratio = 1 : 2 and 1 : 5 can transport over 120 cm. By contrast, the Fe (III) complex A solution at Fe (III) : organic acid (A) molar ratio = 1 : 1 (Fe = 2 mM) only transported less than 80 cm. Thus, it was concluded that using a lower Fe (III) concentration, with elevated organic acid A concentration can increase the Fe (III) transport distance. The gas production in soil column from the Fenton-like decay of 2% H2O2 catalyzed by the Fe (III) complex A at M/M ratio = 1 : 2 (Fe = 0.5 mM) was less than that by M/M ratio of 1: 5. The Fenton-like reaction catalyzed by the studied Fe (III) complex A at Fe (III): organic acid A molar ratio = 1 : 2 can successfully catalyze H2O2 and oxidize benzene and toluene in soil column. It was found that the Fe (III) complex A also acted as a co-solvent during transport which enhanced benzene and toluene movement in soil columns.

碩士
國立屏東科技大學
環境工程與科學系所
98
When oils or BTEX from the petrochemical factory or the gas station, wwre seriously released to the subsurface, non aqueous phase liquids (NAPLs) often exist in underground. NAPLs are the origin of the vapor, sorbed and dissolved phases of pollutants in the soil and aquifer. The in situ technology to treat the NAPLs, may enhance remediation efficiency and reduce the treatment periods. Fenton-like process is one of the in situ chemical oxidations. The Fe (III) complex were developed recently as new catalysts for the Fenton-like oxidation process. Organic acids or chelates were complexed with iron ion and kept the iron ion stable in the solution and therefore maintain the oxidation efficiency. This study evaluated the Fenton-like reaction of toluene NAPL, catalyzed by an Fe (III) complex (named complex A) in batch reactors and soil columns, using the optimum Fenton-like reaction conditions found previously. The results in toluene NAPL oxidation batch experiments found that complex A catalytic ability for Fenton-like reaction is more effective at higher pollutant concentrations. Multipie doses of low H2O2 concentrations resulred in less clogging and more toluene removal than a single doses of high H2O2. The Fenton-like reaction catalyzed by the studied Fe (III) complex A can successfully catalyze H2O2 and oxidize toluene NAPL in the soil column. More toluene was eluted out from the soil columns by Fe (III) complex A, showing that flushing was one of the removal mechanisms.

碩士
國立中山大學
環境工程研究所
98
Abstract The object of this study was to investigate the synthesis of a nanoscale zero-valent iron slurry (NZVIS) for use in Fenton-like reactions, and to evaluate its efficiency for As(III) oxidation to As(V) in spiked deionized water and simulated groundwater containing humic acid. Furthermore, this study used injection of the nanoiron slurry combined with electrokinetic processes to remediate As(III) in soil. NZVI was prepared by a chemical reduction process. The efficiency of using 3 wt% soluble starch (SS) to stabilize NZVI was also studied. It was found that the SS could keep the nanoparticles dispersed for over one day. The NZVI was characterized by XRD, FE-SEM, ESEM-EDS, and EDS-mapping, to observe its morphology and crystal structure. In this research the iron species observed took non-crystalline forms. In water batch tests, studies in deionized water were compared with those in simulated groundwater with humic acid, and dissolved oxygen content was adjusted. Injection of NZVIS oxidized As(III) to As(V) in all cases. In both deionized water and simulated groundwater, it was found that when the dissolved oxygen(DO) content was not increased, the NZVIS generated non-selective oxidant OH‧, thus reducing the As(V) production rate. When dissolved oxygen content was increased, the DO oxidized organic matter present in the simulated groundwater, allowing the OH‧ to react further with As(III) and increasing the As(V) production rate. Finally, a test was performed in actual groundwater under optimal reaction conditions, without increasing the dissolved oxygen content, for comparison of As(V) yield. The concentration of As(V) was found to be higher in this test (As(V) Conc. = 17.55 μg/L) than when using simulated groundwater (As(V) Conc. = 4.63 μg/L). This study further examined NZVIS injection combined with electrokinetic (EK) technology for the remediation of soil columns containing a low concentration (initial conc. = 100 mg/kg) and a high concentration (initial conc. = 500 mg/kg) of As(III). EK alone without injection of NZVIS (Test E-1) resulted in a residual soil As(V) concentration of 24 mg/kg in the low-concentration test group. In Test E-2, where NZVIS was injected into the anode reservoir, and Test E-3, where NZVIS was injected into the cathode reservoir, residual soil As(V) concentrations were 2.3 mg/kg and 3.4 mg/kg, respectively. The high-concentration test group was comprised of Test E-4 (EK alone without injection of NZVIS), Test E-5 (NZVIS injected into anode reservoir), and Test E-6 (NZVIS injected into cathode reservoir). In these tests, only soil sections 0.2 and 0.4 (normalized distance from anode reservoir) met soil regulation standards. Residual As(V) concentrations in soil sections 0.6, 0.8, and 1.0 are much higher than the regulatory standard. In soil section 1.0, the residual As(V) concentration was less in Test E-6 than in Test E-5 (116.6 mg/kg and 183.5 mg/kg, respectively). This may be because at high pH values, the iron surface does not corrode, instead arsenic adsorption prevails. Only a fraction of negatively charged As(V) species will migrate towards the anode resulting in a relatively low soil As(V) concentration near the cathode.

碩士
國立成功大學
環境工程學系
103
Fenton-like reactions is a soil and groundwater chemical oxidation remediation technology achieved by using iron oxides to catalyze H2O2 and produce free hydroxyl radicals to destroy the organic pollutants in the soil or groundwater. In this study, the efficiency of Fenton-like material synthesis from multi-iron oxides for permeable reactive barriers (PRBs) was evaluated. During Fenton-like reaction, permeable reactive material will catalyze H2O2 decomposition, forming hydroxyl free radicals (•OH) with high oxidation capacity to remove benzene and MTBE from solution. The analysis of •OH generated in Fenton-like reactions through taking pCBA (para-chlorobenzoic acid) as the probe compound. Monitoring the change in concentration of the •OH -probe compound provides an indirect measurement of the •OH concentration. Continuous column experiments were carried out under dynamic flow conditions, showed from grinding filling column and block filling column tests. The reduction of pCBA follows a pseudo-first-order kinetics while the performance of •OH releasing was excellent and stable until 25 hours of period. When initial H2O2 concentration is 800 mg/L, in the test with grinding filling column, the maximum removal rates for benzene and MTBE were 96% and 67%, while in the test with block filling column, those were 73% and 53%, respectively.

碩士
國立成功大學
環境工程學系
102
One of the most common sources for BTEX and MTBE contamination of soil and groundwater are spills involving the release of petroleum products such as gasoline, diesel fuel and lubricating and heating oil from leaking oil tanks. Fenton-like reaction is a soil and groundwater chemical oxidation remediation technology derived from Fenton reaction. This remediation technology is achieved by using iron oxides to catalyze H2O2 and produce free hydroxyl radicals to destroy the organic pollutants in the soil and groundwater. The pCBA was used as a•OH-probe compound in this study. Monitoring the change in concentration of the•OH-probe compound provides an indirect measurement of the•OH concentration. BETX and MTBE are used as target pollutant, hoping to investigate the relationship between the releasing efficiency of OH free radicals and the removal efficiency of BTEX/MTBE. Results from this research showed IBM was suitable for the Fenton-like reactions because of their high iron content. The releasing efficiency of system OH free radicals can be discussed with pCBA pseudo-first-order model. It can tell from the result that the transient steady-state OH free radical concentration of pure iron oxides is greater than IBM (A). The reaction efficiency of IBM (A) is significantly greater than IBM (B). The optimal conditions of the releasing efficiency of OH free radical, the benzene removal rate of FeO, Fe3O4, Fe2O3, IBM (A) and (B) were 98%, 64%, 45%, 65% and 55% respectively, while the MTBE removal rate of FeO, Fe3O4, Fe2O3, IBM (A) and (B) were 46%, 24%, 19%, 47% and 33% respectively.

碩士
國立成功大學
環境工程學系碩博士班
100
An-Shun plant of China Petrochemical Development Corporation (CPDC) has been given much attention globally because of its highly contaminated soil by dioxins, mercury, and pentachlorophenol, and the contaminated area was estimated about 40 hectares. This study mainly focused on the decomposition of dioxins due to their high toxicity, persistence, and bioaccumulation. Besides, some studies indicated that dioxins can pass through the food chain causing hazard to health. It has been proved that dioxins can be decomposed efficiently by hydroxyl radicals generated from Fenton and Fenton-like reactions, which are driven by mixing ferrous ions or iron oxides with hydrogen peroxide (H2O2). On the other hand, iron slags/sludges are by-products of steel-making processes, so that they contain large amounts of iron or iron oxides, possessing the potential as iron sources of Fenton-like reactions. In this study, Fenton and Fenton-like reactions were used to treat soil contaminated by 4-chlorophenol (4-CP) and dioxins. Besides, iron slag/sludge agents (ISA) produced from iron slag/sludges were used in Fenton-like reactions to achieve the goal of destruction of organic pollutants in soil from An-Shun plant. From the results, ISA produced from magnetic iron slag/sludges was suitable for the Fenton-like reactions because of their high iron content and low acid neutralization capacity. The results of the degradation of 4-CP contaminating soil suggest that ISA are feasible iron sources for Fenton-like reactions, and both Fenton/Fenton-like reactions are suitable for treating 4-CP contaminating soil. With [4-CP] = 1500 mg/kg, the optimal conditions for Fenton reactions were pH = 3, [ferrous sulfate] = 9 mM, and [H2O2] = 29.41 mM. Furthermore, an 100% removal efficiency was achieved in 30 min. For Fenton-like reactions, the optimal conditions were pH = 3, [ISA] = 100 g/kg, and [H2O2] = 73.53 mM, and an 100% removal efficiency was also achieved in 30 min. The analysis of fourier-transform infrared spectrometer (FT-IR) and the concentration of chlorine ions showed that the chlorine bonds and aromatic ring can be decomposed by Fenton/Fenton-like reactions. The concentration of dioxins (Cdioxins) was the highest for the soil from An-Shun plant with particle size less than 0.062 mm, and lower for 0.25～2 mm, then 0.062～0.125 mm, and the lowest for 0.125～0.25 mm. The main compounds of dioxins were OCDD, OCDF, 1,2,3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8-HpCDF. In addition, the R2 value between total organic carbon (TOC) content and Cdioxins of soil is 0.709, meaning the binding capability of soil and dioxins is affected by TOC content. The optimal conditions for treating dioxins contaminating soil with Fenton reaction were pH = 3, [ferrous sulfate] = 6 mM, and [H2O2] = 15%, and a 63% removal efficiency is achieved in 24 hours. For Fenton-like reaction, the optimal conditions were pH = 3, [ISA] = 100 g/kg, and [H2O2] = 10%, and a 68% removal efficiency was achieved in 24 hours.