Добірка наукової літератури з теми "Modified-Fenton"

Advanced oxidation processes (AOPs) such as H2O2/UV, O3/H2O2, modified Fenton, and modified photo-Fenton processes have been investigated in terms of the treatment of landfill leachate with ratio of BOD5/COD in the range of 0.22 to 0.24. The modification of Fenton and photo-Fenton processes consisted in the inclusion of precipitation and separation of humic substances at pH 3. Due to the precipitation, the value of COD decreased by 39% and BOD5by 7.1%. The modification of the processes allowed us to improve the efficiency and to decrease the doses of reagents necessary to continue the process. Modified photo-Fenton process proved to be the most effective (92.7% COD removal) of all processes investigated. Additionally, modified-Fenton process was much more effective than the other two processes when compared up to 120 min, while after longer times it gave the least satisfactory results. After 30 min of modified-Fenton process BOD5/COD ratio increased to 0.43. The parameter referred to as “efficiency of oxidants” was used to estimate the efficiency of all the processes—its value varied from 178 to 239%. Various substances including phthalates, hydrocarbons, silanes, and siloxanes were identified in raw and treated leachate.

AbstractThe Fenton reaction is supposed to play a key role in the initial wood degradation by brown rot fungi. Wood was modified with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and glutaraldehyde (GA) to various weight percentage gains in order to study if these types of modifications are able to reduce wood degradation by Fenton reagent. Veneers modified with higher concentrations (1.2 and 2.0 mol l-1) of both chemicals exhibited minor losses in mass and tensile strength during treatment with Fenton reagent, which shows restrained oxidative degradation by hydroxyl radicals. The decomposition rate of H2O2was lower in the Fenton solutions containing modified veneers than in those containing unmodified controls. More CO2evolved in systems containing unmodified veneers than in systems with modified veneers, indicating that modification protected wood from mineralisation. The reason for the enhanced resistance of modified wood to the Fenton reaction is attributed to impeded diffusion of the reagent into the cell wall rather than to inhibition of the Fenton reaction itself. The results show that wood modification with DMDHEU and GA is able to restrain the degradation of wood by the Fenton reaction and can explain why modified wood is more resistant to brown rot decay.

ABSTRACT An approach to decontamination of biological endospores is discussed. Specifically, the performance of an aqueous modified Fenton reagent is examined. A modified Fenton reagent formulation of cupric chloride, ascorbic acid, and sodium chloride is shown to be an effective sporicide under aerobic conditions. The traditional Fenton reaction involves the conversion of hydrogen peroxide to hydroxyl radical by aqueous ionic catalysts such as the transition metal ions. Our modified Fenton reaction involves the conversion of aqueous dissolved oxygen to hydrogen peroxide by an ionic catalyst (Cu2+) and then subsequent conversion to hydroxyl radicals. Results are given for the modified Fenton reagent deactivating spores of Bacillus globigii. A biocidal mechanism is proposed that is consistent with our experimental results and independently derived information found in the literature. This mechanism requires diffusion of relatively benign species into the interior of the spore, where dissolved O2 is then converted through a series of reactions which ultimately produce hydroxyl radicals that perform the killing action.

The degradation of Reactive Red 120 dye (RR-120) in synthetic waters was studied. Two processes were considered: homogeneous sono-Fenton with iron(II) sulfate and heterogeneous sono-Fenton with synthetic goethite and goethite deposited onto silica and calcite sand (modified catalysts GS and GC, respectively). In 60 min of reaction, the homogeneous sono-Fenton process allowed a degradation of 98.10 %, in contrast with 96.07 % for the heterogeneous sono-Fenton process with goethite at pH 3.0. The removal of RR-120 increased when the modified catalysts were used instead of bare goethite. Chemical oxygen demand (COD) and total organic carbon (TOC) measurements showed that the highest TOC and COD removals were achieved with the homogeneous sono-Fenton process. Biochemical oxygen demand (BOD5) measurements allowed confirmed that the highest value of BOD5/COD was achieved with a heterogeneous sono-Fenton process (0.88?0.04 with the modified catalyst GC), demonstrating that the biodegradability of the residual organic compounds was remarkably improved.

Background: and Aim The leachate from oil sludge compost into the environment, which is resistant to decomposition, causes several environmental problems. Therefore, it needs to be treated using efficient processes. This study aimed to investigate the efficiency of the modified Fenton process for treating these oil sludge leachates. Methods & Materials: In this experimental study, leachate samples were collected, and then modified Fenton solution was prepared by adding Fe2 (SO4) 3 to H2O2. Then the effect of time parameters (15, 30, 60, 90, and 120 minutes), modified Fenton concentration of 20, 50, 100, and 200 mg/l with pH 3, 5, 9, and three initial concentration of COD (500, 1000 and 1500 mg/l) was examined. Ethical Considerations: This study has been registered in Arak University of Medical Sciences with codes 2645 and 2765. Results: The reduction of COD and TPH in the optimal time of 60 minutes, initial COD of 500 mg/l, pH of 3, and Fenton concentration of 200 mg/l were 9.04 and 77.42%, respectively. The experiments showed that the removal efficiency of COD and TPH with increasing residence time and the concentration of modified Fenton are directly proportional and with decreasing, the initial concentration of COD and pH is inversely proportional. Conclusion: The use of modified Fenton is an efficient method for treating leachate from petroleum sludge compo

This study investigated the effect of ultraviolet (UV) enhancement and the Fe3+-EDTA Complex on the degradation of methylene blue (MB) in Fenton-like system. By studying different variables including H2O2concentration, Fe3+-EDTA concentration and pH value，and using MB as a model pollutant, the best experimental conditions was to investigated. Experimental results showed that it is possible to degrade MB wastewater effectively by modified UV-Fenton with Fe3+-EDTA at neutral pH. Besides, optimality condition (pH= 7, [Fe3+-EDTA] = 2 mmol/L, [H2O2] = 10 mmol/L) which were used in the modified UV-Fenton that achieves a removal of over 95% of the MB in 60 min reaction time. Therefore, this new modified Fenton system is an effective treatment for MB wastewater.

The graphite felt (GF) was modified by the impregnation method and the potentiostatic oxidation method to improve its application performance in the electro-Fenton (E-Fenton) system. Sulfuric acid and ammonia water were used as modifying reagents. After the GF was modified, its conductivity, adsorption performance and hydrogen peroxide production performance were improved. The original graphite felt (GF0) and the modified GF were used as cathode to degrade methylene blue in the E-Fenton system to explore the practical application performance. The reaction kinetics of the methylene blue degradation process was fitted. The results showed the degradation of methylene blue followed the first-order kinetics. The GF was modified by the potentiostatic oxidation with ammonia as modifying reagent (GFEN) had the best application performance in the E-Fenton system. Degradation of methylene blue for 30 min, the reaction rate constant of GFEN cathode system was 1.71 times higher than GF0 cathode system. The GFEN electrode was reused 10 times in the E-Fenton system, the removal rate of methylene blue was only decreased by 7.14%, and the current was only decreased by 4 mA, which showed its good stability. Finally, the comparison of the electrical energy per order (EE/O) values showed that GFEN can significantly improve the current efficiency of the E-Fenton system.

Degradation of dye wastewater was studied by using nanoferrous modified bentonite as the heterogeneous catalyst for a Fenton-like oxidation. By comparing the effect of homogeneous Fenton reactions as well as heterogeneous Fenton-like process for nanomodified bentonite, it is found that the advanced oxidation processes assisted by nanoferrous/bentonite complexes exhibit the stronger degradation capacity. And the removal rate of Fenton-like reaction increased from 23.6% to 75.5% when the ferrous concentration increasing from 20 to 100mmol/L. Being compared with homogeneous Fenton reactions, 20% increased degradation efficiencies is obtained by Fenton-like oxidation process for nanomodified bentonite under 6g nanoferrous/bentonite complexes in 100mL dye wastewater.

The use of hydroxyl radical based reaction (Fenton reaction) for the destruction of organic pollutants has been widely reported in the literature. However, the low pH requirement and rapid hydrogen peroxide consumption rate make the application of conventional Fenton reaction difficult for in-situ treatment. In this study, we conducted a modified Fenton reaction by introducing a chelating agent into the reaction system that could prevent Fe(OH)3 (s) precipitation even at a neutral pH condition and reduce the H2O2 consumption rate by controlling the Fe2+ concentration. A chelating agent (mono-chelate or poly-chelate) combines with Fe2+ or Fe3+ to form stable metal-chelate complexes in solution. This decreases the concentration of Fe2+ in the solution so that reactions can be carried for longer contact times. Experimental results (citrate was the chelating agent) for 2,4,6-trichlorophenol (TCP) showed that TCP degradations were greater than 95% after 2.5 h and 24 h reaction times at fixed pH 5 and 6, respectively. For the same reaction time, the normalized chloride formations were 85% at pH 5 and 88% at pH 6. Several other chlorinated organic compounds were also chosen as the model compounds for detoxification studies because of their chemical structures: trichloroethylene (unsaturated hydrocarbon), carbon tetrachloride (highly oxidized compound), 2,2-dichlorobiphenyl, and biphenyl (a dual-aromatic ring structure). Poly-chelating agents (such as polyacrylic acid-PAA) provide multiple Fe2+/Fe3+ binding sites in the modified Fenton reaction for the oxidation of contaminants (2,2-dichlorobiphenyl, and biphenyl) at a neutral pH environment. Numerical simulation based on the kinetic model developed from the well known Fenton reaction and iron-chelate chemistry fits experiment data well for both standard and chelate modified Fenton reactions. In this dissertation, it was proven that both monomeric (citrate) and polymeric (PAA) chelate modified Fenton reactions were effective for dechlorination of carbon tetrachloride from aqueous phase by the superoxide radical anion. On the other hand, PAA (a poly-chelating agent) can also be used for solid surface modification by polymerization of acrylic acid (monomer). The successful degradations of biphenyl and trichloroethylene by the PAA functionalized silica particles/membrane demonstrate the versatile applications of the chelate modified Fenton reaction.

Cilj  ovog  rada  bio  je  ispitivanje  mogućnosti  primene  modifikovanog  bentonita  kao katalizatora  (ferioksalat  i  Al,  Fe-bentonit  katalizatori)  u  Fenton  i  foto-Fenton  procesu  uklanjanja tekstilne  reaktivne  boje  Reactive  Red  120.  Do  sada  su  objavljene  studije  primene  heterogenog Fenton procesa sa različitim koncentracijama gvožđau katalizatorima i sa kompleksom ferioksalata,međutim, njihovo poređenje u smislu efikasnosti obezbojavanja nije istraženo, što je bio jedan od fokusa  istraživanja  u  ovom  radu.  Osim  toga,  potencijal  sunčeve  energije  predstavlja  16,7%  od ukupno  iskoristivog  potencijala  obnovljivih  izvora  energije  u  Srbiji,  dok  je  prosečno  sunčevo zračenje  u  Srbiji  oko  40%  više  od  evropskog  proseka,  čineći  ga  vrlo  zanimljivim  za  primenu  u ovom tipu tretmana. U cilju što boljeg iskorišćenjasunčevog zračenja i unapređenja fotokatalitičkih performansi  procesa  primenjen  je  parabolični  koncentrišući  reaktor,  koji  je  za  ovu  vrstu  procesa prvi put upotrebljavan. Proučavano je u kojoj meri je solarna fotokataliza značajan segment tehnike za tretman otpadnih voda tokom degradacije perzistentnih jedinjenja, kao što je organska azo boja. Takođe, utvrđen je i potencijal fotolize vodonik-peroksida za obezbojavanjem sintetičkog rastvora date  boje.  Prva  faza  imala  je  za  cilj  sintezu  materijala  primenom  različitih  metoda  pripreme  ikonstrukciju solarnog paraboličnog reaktora, koji će se koristiti u Fenton i foto-Fenton procesima degradacije boje Reactive Red 120. Druga faza je podrazumevala karakterizaciju novosintetisanih materijala i optimizaciju procesa fotokatalize primenom Fenton i foto-Fenton procesa i određivanje postignutih efikasnosti primenjenih procesa. Takođe, vršeno je određivanje stepena mineralizacije i identifikacija degradacionih produkata nakon procesa degradacije tekstilne boje Reactive Red 120, kao  i  primena  foto-Fenton  procesa  na  realnom  efluentu.  Na  osnovu  dobijenih  rezultata  tokom primene Fenton procesa i korišćenjem oba tipa katalizatora u periodima niskog i visokog intenziteta zračenja,  sa  aspekta  postizanja  visoke  efikasnosti  obezbojavanja  i  najmanjeg  izluživanja  gvožđa,može  se  zaključiti  da  je  Fenton  proces  najefikasniji  na  pH  vrednosti  3.  AlFeB  je  pokazao  veću reaktivnost čak i pri manje upotrebljenim dozama od0,05 g u odnosu na CuOFeB (0,2 g), kao i mogućnost  manje  upotrebe  vodonik-peroksida  od  2,5  mM,  za  postizanje  visoke  efikasnosti obezbojavanja i postignut visok stepen mineralizacije. Viši intenzitet sunčevog zračenja omogućava odvijanje reakcije obezbojavanja na višim pH vrednostima primenom oba katalizatora tokom fotoFenton  procesa.  Ovo  je  posebno  izraženo  kod  CuOFeB  tokom  letnjeg  perioda  (pH  7),  čak  i  pri nižim dozama katalizatora. Međutim, najveći udeo u  procesu obezbojavanja pri upotrebi CuOFeB katalizatora ima fotoliza vodonik-peroksida (80%). Suprotno ovim rezultatima, pri istim reakcionim uslovima,  potrebna  je  veća  količina  AlFeB  katalizatora  (0,1  g)  i  niža  pH  vrednost  reakcije,  a efikasnost  procesa  značajno  zavisi  od  početne  koncentracije  H ₂O₂.  Činjenica  da  se  u  pripremi katalizatora koristio bentonit kao prirodan, širokorasprostranjen i jeftin materijal i solarno zračenje kao obnovljiv i alternativni izvor fotona, gore navedene rezultate bi trebalo uzeti u obzir prilikom analize troškova efikasnosti primenjenog procesa. Takođe, primena unapređenih procesa oksidacije se  razmatra  kao  predlog  za  najbolju  dostupnu  tehniku  kada  je  u  pitanju  tretman  otpadne  vode tekstilne industrije, dok se kao dodatne nove tehnike uzimaju u obzir foto-oksidacije i ispitivanje mogućnosti  njihove  primene  u  prečišćavanju  otpadne  vode  u  tercijarnom  tretmanu  na poluindustrijskim sistemima. 
The aim of this study was to investigate the decolorization efficiency of Reactive Red 120  (RR120) synthetic solution using ferrioxalate (CuOFeB) and Al, Fe-bentonite (AlFeB) catalysts in  Fenton  and  photo-Fenton  process.  So  far,  studies  of the  application  of  a  solar-assisted  heterogeneous Fenton process with various Fe loaded catalysts and with ferrioxalate complex have  been published, but according to   the author’s knowledge, their comparison in terms of efficacy of  decolorization  has  not  been  performed,  which  was  one  of  the  focus  of  research  in  this  paper.  In addition, the potential of solar energy represents  16.7% of the total utilized  potential of renewable  energy sources in Serbia, while the average solar radiation in  Serbia is  about 40% higher than the  European average, making it very interesting for  application in this type of treatment. In order to  optimize the use of solar radiation and to improve  the photocatalytic performance of the process, parabolic  concentrating  reactor  was  used  for  the  first  time.  As  a  significant  segment  of  the  wastewater  treatment  technique  during  the  degradation  of  persistent  compounds,  such  as  organic azo dye, solar photocatalysis was studied. Also, the potential of photolysis of hydrogen peroxide for  decolorization of the synthetic dye solution was determined. Aim of the first phase of the study was synthesizing  materials  by  using  different  methods  of  preparation,  and  construction  of  a  solar  parabolic reactor, which will be used in Fenton andphoto-Fenton dye degradation processes. The second phase involved the characterization of newlysynthesized materials and the optimization of the  photocatalytic  process  by  applying  Fenton  and  photo-Fonton  processes,  as  well  as  the  determination  of  achieved efficiency  of  the  appliedprocesses.  Also, the degree  of mineralization and the identification of degradation products after applied processes were determined. Application  of the photo-Fenton process on a real effluent was conducted as well. Based on the obtained results  during  Fenton  process  and  using  both  types  of  catalysts  in  periods  of  low  and  high  intensity  of  radiation, from the aspect of achieving high efficiency of decolorization and smallest iron leaching,  it  can  be  concluded  that  the  Fenton  process  is  most effective  at  pH  3.  AlFeB  showed  greater  reactivity even at less used doses of 0.05  g, compared to CuOFeB (0.2 g), and the possibility of using  less  hydrogen  peroxide  (2.5  mM),  achieving  high  efficiency  and  a  high  degree  of mineralization. Higher intensity of solar radiationallows the reaction to be carried out at higher pH values when using both catalysts during the photo-Fenton process. This is particularly pronounced largest part in the decolorization process using the CuOFeB catalyst has  a photolysis of hydrogen peroxide  (80%).  Contrary  to  these  results,  under  the  same  reaction  conditions,  a  higher  doses  of AlFeB catalyst (0.1 g) is needed at lower pH value  of the reaction, and the process efficiency is significantly dependent on the initial concentration of H ₂O₂. The fact that in the preparation of the catalysts bentonite as a natural, abundant, inexpensive material was used and solar  radiation as a renewable and alternative source of photons, the above results should  be taken into account in the cost-effectiveness  analysis  of  the  applied  process. Also,  the  application  of  advanced  oxidation processes is considered as a proposal  for the best available technique when it comes to the treatment of  wastewater  from  the  textile  industry,  while  as  additional  new  techniques,  photooxidation  is considered as a candidate and the possibility of their application in the treatment of wastewater in tertiary treatment on semi-industrial systems.

Mes recherches s’inscrivent dans une problématique de remédiation des sols pollués par deshydrocarbures aromatiques polycycliques (HAP) avec comme modèle de polluant organiquepersistant le benzo[a]pyrène (BaP). La persistance de ce type de molécules dans les sols estprincipalement due à deux paramètres limitants : leur faible biodisponibilité en raison de leur faible solubilité aqueuse et la difficulté pour les microorganismes d’amorcer l’oxydation de molécules aussi stables. Notre approche a consisté en l’utilisation de polysaccharides à base d’amidon comme matrice permettant de stimuler la solubilisation du BaP et comme support à la réaction de Fenton (Fe²⁺ + H2O2 → Fe³⁺ + OH- + OH⁺) en tant que producteur d’un puissant oxydant : le radical hydroxyl OH⁺. Une étude théorique de modélisation moléculaire a permis de mettre en évidence dans lamolécule d’amidon des sites de fixation préférentiels aussi bien pour le BaP que pour le cation Fe ²⁺. Par la suite, l’étude expérimentale a eu pour objectif la synthèse chimique d’amidon modifié utilisantdeux types d’agent alkylant, des époxydes et des anhydrides d’acides carboxyliques. Après la caractérisation chimique de ces molécules par spectroscopie RMN et FTIR, les études de relation structure activité (par fluorescence, MEB et MEB-EDS) entre les amidons modifiés, le BaP et le cation Fe ²⁺ ont permis le criblage d’une vingtaine de molécules d’amidons modifiés et la sélection des amidons modifiés les plus solubles et les plus efficaces dans la solubilisation du BaP. Par exemple, la molécules d’amidon (P17) bialkylé par un époxyde à trois carbones et un anhydride à onze carbones présente une solubilité aqueuse de 4,41 g/l (amidon natif 0,4 g/l) et une capacité à stimuler la solubilité du BaP d’un facteur 20. La dernière étape de mon travail de thèse aborde, in vitro, les applications potentielles des amidons modifiés pour la dégradation du BaP. Les essais réalisés avec la réaction de Fenton nous ont suggéré une hypothèse originale dans laquelle il semblerait que la matrice polysaccharique produirait des radicaux carbohydrates possédant un temps de demi-vie largement supérieur comparé à celui de l’hydroxyl radical leur conférant une meilleure capacité à atteindre et à oxyder le BaP. Les premiers essais couplant l’oxydation chimique et les potentialités de dégradation par des champignons saprotrophes doivent être encore optimisés afin d’utiliser tout le potentiel de la biodiversité des champignons
My researchs concern remediation of polluted soil by polycyclic aromatic hydrocarbons (PAH) with the benzo[a]pyrene (BaP) as a model of persistent organic pollutant. The persistence of these molecules into soil is mainly due to both limiting parameters: their weak biodisponibility due to their low aqueous solubility and the difficulty for microorganisms of starting the oxidation of such stable molecules. Our approach consisted in the use of polysaccharides like starch matrix for stimulating the solubilization of BaP and allowing on such support the Fenton reaction (Fe²⁺+H2O2 → Fe ³⁺+ OH -+ OH ⁺) as a producer of high oxidant i.e. the hydroxyl radicals OH ⁺. A theoretical computer modelling study conducted on potato starch permits to identify the preferential sites for BaP and iron complexation. Thereafter, the experimental study aimed the chemical modification of starch using two types of alkylated agents i.e. epoxides and anhydrides of carboxylic acids. After the chemical characterization of these molecules by NMR and FTIR spectroscopy, the structure activity relationship between the modified starches, BaP and Fe2+ (as studied by fluorescence, SEM and SEM-EDS) allowed the screening of modified starches and the selection of the most soluble starches and the most effective one in BaP solubilization. For example, the molecule of starch (P17) bi-alkyl substituted by an epoxy group with three carbons and an anhydride with eleven carbons has an aqueous solubility of 4,41 g/L (native starch 0,4 g/L) and a capacity to stimulate the BaP solubility by a 20-factor. The last step of this work approaches, in vitro, the potential application of the modified starch for BaP degradation. The tests carried out with Fenton reaction suggested an original hypothesis based on the production of carbohydrate radicals having a higher half-life time compared with that of the hydroxyl radical itself, conferring them a better capacity to reach and to oxidize BaP. The first tests coupling chemical oxidation and the potentialities of fungal degradation must be still optimized in order to use all the potential biodiversity of fungi
Cercetările acestei teze se înscriu în cadrul unei probleme de remediere a solurilor poluate cu hidrocarburi aromatice policiclice (HAP),având ca model de poluare benzo [a] pirenul (BaP). Persistenţa acestor moleculelor, de acest tip, în soluri este dată în principal de doi parametri limitanţi: biosponibilitatea lor scăzută, datorită solubilităţii apoase scăzute, şi dificultatea, pentru microorganisme de a oxida aceste molecule stabile. Abordarea nostră constă în utilizarea polizaharidelor, având ca suport amidonul: ca matrice permanentă de stimulare a solubilităţii BaPului şi ca suport în reacţia Fenton (Fe²⁺+H2O2 → Fe ³⁺+ OH -+ OH ⁺) producătoare de un oxidant foarte puternic precum radicalul hidroxil OH ⁺. Un studiu teoretic de modelare moleculară a permis punerea în evidenţă în molecula de amidon a unor site-uri de fixare preferenţiale atât pentru BaP cât şi pentru cationul Fe²⁺. Apoi, un studiu experimantal a avut ca obiectiv sinteza chimică a amidonului modificat utilizând două tipuri de agenţi de alchilare: epoxizii şi anhidridele acizilor carboxilici. După caracterizarea chimică a acestor molecule prin spectroscopie RMN şi FTIR, studiile de relaţie structură-activitate (prin fluorescenţă, MEB şi MEB-EDS) între amidonurile modificate, BaP şi cationul Fe²⁺ au permis verificarea a douăzeci de molecule de amidon modificate şi selecţionarea amidonurilor modificate cele mai solubile şi mai eficace în solubilizarea BaPului. De exemplu, molecula de amidon (P17) bialchilată printr-un epoxid cu trei atomi de carbon şi o anhidridă cu unusprezece carboni, prezintă o solubilitate apoasă de 4,41 g/L (faţă de amidonul nativ 0,4 g/L) şi o capacitate de stimulare a solubilităţii BaP de un factor 20. Ultima etapă a acestei teze de doctorat abordează, in vitro, aplicaţiile potenţiale ale amidonurilor modificate pentru degradarea BaPului. Încercările realizate cu reacţia Fenton ne sugerează o ipoteză originală în care se pare că matricea polizaharidică produce radicali carbohidraţi posedând un timp de viaţă superior, comparativ cu cel al radicalului hidroxil, conferind o mai bună capacitate de captare şi oxidare a BaPului. Primele încercări cuplând oxidarea chimică şi potenţialitatea de degradare prin fungi saprotrofi mai trebuie încă optimizată pentru utilizarea întregului potenţial de biodiversitate a fungilor

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This study was to evaluate the modified Fenton reactions (RFM), through the addition of six complexing organic separately in each reaction, these being: ascorbic acid (AA), citric acid (CA), ethylenediaminetetraacetic acid (EDTA), gluconic acid (AG), oxalic acid (OA) and tartaric acid (TA), the degradation of textile effluent under varying molar ratios between the total organic carbon, [Fe2+], complexing and [H2O2]. In RFM and Fenton reactions (RF) reactor was used consisting of a borosilicate beaker with a maximum volume of 250 mL, in batch, open, without stirring under room temperature in the optimization phase of time aliquots were removed in the effluent times: 0, 3, 6, 9, 12, 15, 18, 21 and 24 h. The procedure consisted of addition of 250 mL of textile effluent to the reactor for RF and RFM, followed by the oxidant and a catalyst for the RF and oxidizing catalyst and complexing to RFM. RF best results in reduction of TOC was obtained in 12 h treatment under initial pH value of 3.0 and a molar ratio [1:0,9:27,5]. Concerning the [COT:Fe2+:H2O2] where noted a reduction of 91.06% of TOC, COD 94.51%, 99.88% and 99.02% of the turbidity of discoloration. The RFM showed the best results with the use of complexing GA at 15 h of treatment under molar ratio [1:1,31:1,12:27,94], its [COT:Fe2+:AG:H2O2] which promoted reduction of 82.30% of TOC, COD 90.53%, 99.27% and 99.19% of the turbidity of discoloration, TA had similar results in reduction of parameters when the effluent subjected to 12 h of treatment in a molar ratio [1:0,76:0,94:32,13]. Concerning the [COT:Fe2+:AT:H2O2] under these conditions was possible to reduce 75.05% TOC, 94.89% COD, 97.84% turbidity and discoloration of 96.75%. However, RF are effective in the treatment of textile effluents, though the RFM presented as a new possibility of the treatment without the necessity of adjusting the initial pH value.
Este estudo teve por objetivo avaliar as reações de Fenton modificadas (RFM), através da adição de seis complexantes orgânicos isoladamente em cada reação, sendo estes: ácido ascórbico (AA), ácido cítrico (AC), ácido etilenodiaminotetracético (EDTA), ácido glucônico (AG), ácido oxálico (AO) e ácido tartárico (AT), na degradação de efluente têxtil, sob variadas relações molares entre o carbono orgânico total, [Fe2+], complexante e o [H2O2]. Nas RFM e reações de Fenton (RF) foi utilizado reator constituído por um béquer de borossilicato com volume máximo de 250 mL, em sistema descontínuo, aberto, sem agitação, sob temperatura ambiente, na fase de otimização do tempo alíquotas do efluente eram retiradas nos tempos: 0, 3, 6, 9, 12, 15, 18, 21 e 24 h. O procedimento consistiu na adição de 250 mL do efluente têxtil ao reator para as RF e RFM, seguido do oxidante e catalisador para as RF e oxidante, catalisador e complexante para as RFM. Nas RF os melhores resultados de redução do COT foi obtido em 12 h de tratamento, sob valor de pH inicial 3,0 e relação molar [1:0,9:27,5] referente ao [COT:Fe2+:H2O2] aonde constatou-se redução de 91,06% do COT, 94,51 da DQO, 99,88 da turbidez e 99,02% de descoloração. As RFM apresentaram os melhores resultados com a utilização do complexante AG em 15 h de tratamento sob relação molar [1:1,31:1,12:27,94], respectivo [COT:Fe2+:AG:H2O2] a qual promoveu a redução de 82,30% do COT, 90,53% da DQO, 99,27% da turbidez e 99,19% de descoloração, o AT apresentou resultados similares de redução dos parâmetros avaliados, quando submetido o efluente a 12 h de tratamento sob relação molar [1:0,76:0,94:32,13] referente ao [COT:Fe2+:AT:H2O2], nestas condições foi possível a redução de 75,05% do COT, 94,89% da DQO, 97,84% da turbidez e descoloração de 96,75%. Contudo, as RF são eficazes no tratamento de efluentes têxteis, entretanto as RFM apresentam-se como uma nova possibilidade de tratamento sem a necessidade de ajuste do valor do pH inicial.

Grâce au développement continu de technologies d'analyse environnementale, certains produits chimiques, qui sont reconnus être nocif, ont récemment attiré l'attention, puisqu'ils constituent un menace pour l'environnement et la santé publique.Parmi ces polluants émergent, les produits pharmaceutiques et de soins personnels (PPSP)sont devenus le cibles dela recherche internationale. La chine est le plus grand producteur et le marché des médicaments dans le monde. Avec le développement de l'économie sociale et l'amélioration du niveau de vie de la population, de la production et de l'utilisation de divers PPSP présents en chine augmente rapidement. Par comparaison avec les polluants classiques, ces contaminants émergents sont généralement difficiles à analyser en raison de la limitation de technologies analytiques et de sa faible concentration dans les eaux naturelles.Les usines traditionnelles de traitement des eaux usées ne peuvent pas éliminer efficacement ces produits. La recherche sur l'évaluation des risques et le contrôle des nouveaux contaminants émergents, en chine constitue actuellement un grand défi. Il est donc essentiel de renforcer la recherche sur l'évaluation des risques pour l'environnement et les technologies de traitement efficaces pour éliminer ces polluants émergents. Les procédés d'oxydation avancée (POA) constituent une technologie de traitement efficace et ont été largement utilisés dans le traitement des polluants organiques réfractaires tels que les la destruction des contaminants émergents en milieu aqueux à cause de leur forte pouvoir d'oxydation permettant une minéralisation in situ des polluants. Le graphite, comme un nouveau type de matériau carbone adsorbant, est devenue un matériau d'électrode pour le traitement de la pollution due à son excellente conductivité et surface spécifique très élevée. Toutefois, son application dans les AOPs n'a pas été largement étudié et le mécanisme d'oxydation n'a pas été expliquée de manière systématique. Par conséquent, ce travail présent une étude détaillée sur le rôle des électrodes graphite modifiées dans les procédés électrochimiques d'oxydation avancée (PEOA) avec la préparation électrochimique des électrodes modifiées au graphène par exfoliation, et leur application dans le PEOA "électro-Fenton" (EF) pour le traitement des contaminants émergents. Ainsi le cathode en feutre de carbone modifiée au graphène a permis de d'éliminer différents contaminants émergents sans utilisation d'ions ferreux (catalyseur du procédé électro-Fenton) car les radicaux hydroxyles sont générés à travers d'un procédure catalytique grâce à la dopage du graphène à l'azote. Ensuite les cinétiques de dégradation et de minéralisation ainsi que les mécanismes d'oxydation de différents contaminants émergents ont été explorées
In recent years, with the continuous development of environmental analysis technologies, some chemicals, which have long been recognized but recently attracted attention, have been continuously entering the environment and threatening human health and ecological environment. The emergence of these new pollutants have attracted wide attention. Among them, pharmaceuticals and personal care products (PPCPs) have become international research hotspots. China is the largest medicine producer and market in the world. With the development of social economy and the improvement of people's living standards, the production and use of various PPCPs in China are increasing rapidly. Compared with the traditional pollutants, the new emerging contaminants are generally difficult to be analyzed due to the limitation of analytical technologies and its low concentration in water. The traditional sewage treatment plants can not achieve efficient degradation and removal effects. The research on risk assessment and control of new emerging contaminants in China is still a big challenge. It is necessary to strengthen the research on potential environmental risk assessment and efficient treatment technology. Advanced oxidation processes (AOPs), as an efficient pollutant treatment technology, has been widely used in the treatment of refractory organic pollutants such as new emerging contaminants in water because of its strong oxidation ability, which can effectively degrade and mineralize pollutants in water. Graphene, as a new type of carbon material, has become an efficient adsorbent and catalyst for pollution treatment due to its excellent conductivity and high specific surface area. However, its application in AOPs has not been widely reported and its mechanism has not been systematically explained. Based on this, this paper studied the role of graphene modified electrodes in electrochemical advanced oxidation processes (EAOPs) with the preparation of graphene by electrochemical exfoliation, application of graphene modified electrodes to electrochemical Fenton (EF) process for the degradation of new emerging contaminants; the construction of in-situ iron-free EAOPs with cathodes modified with nitrogen-doped graphene for abatement of new emerging contaminants and the mechanism of highly efficient catalysis with nitrogen-doped graphene have been explored

碩士
國立屏東科技大學
環境工程與科學系所
95
The pollutants from the leaking pipeline and storage tanks of petrochemicals are likely to cause soil and aquifer contaminations. The chemical oxidation is successful in remediating soil and aquifer contamination. The mixture of Fe（II） and H2O2 soluton was called Fenton reagent. The Fe（II） ion can catalyze H2O2 to produce hydroxyl radicals (˙OH). The ˙OH is very powerful in oxidizing organic pollutants, reducing their toxicity or even mineralizing them to H2O and CO2. However, the Fenton reagent has limitations such as it reacts more effectively at pH=2~3 and produces precipitates which will cause clogging. Recently, it was found that other Fe-containing compounds work better than Fe（II） ion in catalyzing H2O2 at neutral pH. The Fenton reaction catalyzed by non-Fe（II） ion was called Fenton-like reaction. There are many new catalysts tested nowadays. This study used batch reaction systems to evaluate an Fe（III）/organic acid complex, developed by a consultant firm, to be used as the catalyst of Fenton-like reaction. Using O2 production and decolorization of methylene blue dye as indices, the results showed that H2O2 can be effectively and repeatedly catalyzed by the tested Fe（III）-organic acid complex. White precipitates were observed at acidic pH, but not at neutral pH. Higher molar concentrations of organic acid can prevent the precipitation or adsorption of Fe（III） ions, and maintain the catalytical ability of the catalyst in a sandy loam soil. The kinetics result showed that the reaction order for Fenton-like reaction of benzene using the catalyst at Fe（III）: organic acid molar ratio = 1:1,1:2,1:5 and 1:10 was first order. In addition, the kinetic constants at Fe（III）: organic acid molar ratio = 1:1 were linearly proportional to the initial concentration of benzene. On the other hand, there was no consistent relation observed for the kinetic constant with benzene concentration for other molar ratios of Fe（III）/organic acid.