Ce travail a pour objectif de développer un procédé couplant séparation membranaire et oxydation (photo-) Fenton hétérogène pour l’élimination du paracétamol dans l’eau. La réaction a d’abord été étudiée avec le fer en solution à pH acide (2,6) pour servir de référence aux études hétérogènes ultérieures. La méthodologie des plans d’expériences a permis de déterminer les paramètres influents (parmi température, concentrations d’oxydant et de catalyseur) et leurs interactions, et de modéliser les performances du procédé homogène. Des oxydes de fer sous la forme de particules nano- et micro-structurées (hématite, maghémite et magnétite) ou supportés sur zéolithes (type MFI ou BEA) ont ensuite été testés comme catalyseurs de l’oxydation Fenton. Pour chaque système étudié, on a évalué la conversion du polluant et du Carbone Organique Total (COT), mais aussi la stabilité du catalyseur : quantité de fer lixivié et activité du métal passé en solution (pour découpler la contribution du mécanisme homogène associé). L’effet des paramètres opératoires a ensuite été à nouveau évalué pour les catalyseurs sélectionnés (magnétite nanostructurée et Fe/MFI). Pour l’oxyde non supporté, l’étude met en évidence le rôle positif d’une augmentation de la température. A température et pH donnés, le rapport initial [oxyde de fer] / [H2O2] apparaît aussi comme le paramètre essentiel qui contrôle le taux de minéralisation, avec une inhibition de la réaction lorsque H2O2 est en trop large excès. Au contraire, pour le catalyseur Fe/MFI, une augmentation de la concentration d’oxydant se révèle bénéfique (sa consommation étant pratiquement totale dans tous les cas), et il y a peu d’effet de la température. Par ailleurs, la magnétite se révèle efficace à pH acide uniquement, tandis que le catalyseur supporté présente la même activité avec ou sans acidification préalable. L’irradiation UV améliore les performances de ces deux catalyseurs avec un abattement du COT en solution jusqu’à 70% en 5 heures, contre 98% pour le système homogène dans des conditions similaires. Les premiers tests en continu avec des particules de Fe/MFI retenues par une membrane d’ultrafiltration immergée sont prometteurs, puisque l’activité est restée stable pendant plus de 40 h. / This work aims to develop a process coupling membrane separation and heterogeneous (photo-) Fenton oxidation for the elimination of paracetamol in water. The reaction was first studied with dissolved iron in acidic solution (pH 2.6), as a reference for the subsequent heterogeneous studies. The methodology of experimental design was used to determine the significant parameters (including temperature, oxidant and catalyst concentrations) and their interactions, and to model the performance of the homogeneous process. Iron oxides as nano- and micro-structured particles (hematite, maghemite and magnetite) or supported on zeolites (MFI or BEA type) were then tested as catalysts for the Fenton oxidation. For each studied system the conversions of pollutant and Total Organic Carbon (TOC) were evaluated, as well as the catalyst stability: amount and activity of leached iron (in order to decouple the contribution of homogeneous mechanism). The effect of process parameters was then again evaluated for the selected catalysts (nanostructured magnetite and Fe/MFI). For magnetite, the study reveals a positive effect of temperature. At given temperature and pH, the initial ratio of [iron oxide] to [H2O2] also appears as a key parameter that controls the mineralization yield, with an inhibition of the reaction when H2O2 is in large excess. Conversely, for Fe/MFI catalyst, the increase in oxidant concentration is beneficial (oxidant being almost fully consumed in all cases), and temperature has a poor effect. Furthermore, magnetite is only effective at acidic pH, while supported catalyst exhibits same activity with or without prior acidification. UV irradiation improves the performance of these catalysts with a reduction of TOC in solution up to 70% within 5 hours, against 98% for the homogeneous system under similar conditions. The results of the first continuous test, performed with Fe/MFI particles retained by a submerged ultrafiltration membrane, are promising: a stable activity has been observed for over 40 h.

This work increased the value of ferrite process (FP) in three directions: firstly, changed the inferiority of FP on cost by transforming the FP sludge into a catalyst; secondly, used ERFP and elutriation to promote the performance of FP; thirdly, developed Fenton oxidation as a pretreatment step for avoiding the interference from chelating agents. Six ferrite catalysts (MxFe(3-x)O4, M = Cu, Zn, Mn, Ni, Cr or Fe) formed from FP were tested. Experimental results indicate that the Cu-ferrite catalyst with a Cu/Fe ratio of 1/2.5 can completely convert CO to CO2 at an inlet CO concentration of 4000 ppm and a space velocity of 6000 hr-1 were held at 140¢J. The catalytic performance of Cu-ferrite did not reduce even when the concentration of O2 was just 1%. This work proves that the ferrite catalysts have good potential for catalyzing oxidation. For developing FP for effectively treating almost all heavy metal waste liquid, hence an extremely difficult treating target- simulated waste liquid was designed. It contains ten heavy metals - Cd, Pb, Cu, Cr, Zn, Ag, Hg, Ni, Sn and Mn, each at a concentration of 0.002 M. Although conventional FP could not be used to treat the simulated waste liquid completely, the enhanced FP, i.e. ERFP, could be used to satisfy regulatory limits. FeSO4 can be added in the extended stage of ERFP intermittently rather than continuously. The optimum operating parameters in the initial stage are pH = 9 , FeSO4 dosage = 0.2 mol/L, temperature = 90 oC, air supply rate = 3 L/min/L and reaction time = 40 min; in the extended stage, they are intermittent dosing, adding 10 mL 1M-FeSO4 solution per liter waste liquid every 5 min, pH = 9, temperature = 90 oC, air supply rate = 3 L/min/L and reaction time = 80min. Elutriation was conducted to reduce the cost of ERFP and ensure that the sludge met Toxicity Characteristic Leaching Procedure (TCLP) standards. An operating pH from 2.88 to 4 and an elutriation time of 6 h were recommended. Used Fenton oxidation to decompose chelating agent in waste liquid and then treated heavy metal by FP, this research showed that under proper operational conditions Fenton/ ERFP could completely solve the chelating agent interference problem. The best condition for decreasing EDTA using the Fenton method was: pH = 2, ferrous ion initial concentration [Fe2+]0 = 1¡Ñ10-2M, hydrogen peroxide addition rate = 5¡Ñ10-4 mol/min/L and reaction time = 10 min. Lastly, a lot of real waste liquids were treated satisfactorily by applying the results of this study.

In this study, aerobic biological treatment of opium alkaloid wastewater and the effect of gamma preirradiation and fenton&amp / #8217 / s oxidation were investigated. First, the biodegradability of alkaloid wastewater was investigated by batch reactors and wastewater was found to be highly biodegradable providing 83 &amp / #8211 / 90 % COD degradation. In order to evaluate the effect of irradiation, original wastewater and irradiated wastewaters (40 &amp / 140 kGy) were compared by means of BOD5/COD values and through aerobic batch experiments. Results indicated that irradiation imparted no further enhancement in biodegradability. Sequencing batch reactor (SBR) studies revealed that the treatment operation was not possible due to sludge settleability problem observed beyond an influent COD value of 2 g/L. Possible reasons for problem were investigated, and the high molecular weight, larger size and aromatic structure of the organic matters present in wastewater was thought to contribute to poor settleability characteristics. Some operational modifications including phosphate buffer addition cured the settleability problem. Influent COD was then increased to 5,000 mg/L. Significant COD removal efficiencies (&gt / 70 %) were obtained in SBRs fed with both original and irradiated wastewaters. Preirradiated wastewater provided a better settling sludge in comparison to original wastewater. Degradation of the complex structure was followed by GC/MS analyses, particle size measurements and enhancement in filterability. Pre-irradiation enhanced the filterability of wastewater more than Fenton&amp / #8217 / s treatment and degradation by irradiation was proved by GC/MS analyses.

In this master thesis, the feasibility of Fenton-oxidation for the decolorization of reactive dyed cotton is investigated as a potentially environmental-friendly preparatory treatment for mechanical/chemical recycling. Raw, knitted cotton is dyed with a black and a blue dye, whereafter preliminary tests are performed to investigate the influence of increasing Fenton- solution concentrations and different iron-sources on the efficiency of the discoloration, without carrying out complete optimization of the process-parameters. Based on the preliminary test-results, Fenton-treatments of the reactive-dyed cotton are upscaled, with discoloration efficiencies of 62 and 73% (for the black- and blue-dyed cotton respectively). Thermal analysis (TGA, DSC and FTIR) and mechanical analysis (tensile tests and shredding of the fabric) of the upscaled treated samples are performed, and the results indicate no major alterations of the main cellulosic structure of the cotton fibers. However, besides the degradation of the dye-molecules, also some oxidation (and therefore damage) of the cellulose-chains of the cotton fibers occurs, leading to reduced mechanical properties. Although this facilitates the mechanical recycling process, it possibly also reduces the quality of the re-spun yarns. Nevertheless, the Fenton-oxidation in the context of decolorization of reactive-dyed cotton forms an interesting future research-topic with many opportunities and prospects for increasing the efficiency and sustainability of the recycling process, and therefor increasing the sustainability of the textile industry in general.

Landfilling is the most common approach to dispose of municipal solid wastes but inevitably leads to leachate formation. Persistent UV quenching substances (UVQS) in landfill leachate can affect the effectiveness of UV disinfection in municipal wastewater treatment systems when leachate co-treatment is applied. Membrane electrochemical reactor (MER) treatment was investigated to reduce the UV quenching capability and simultaneously recover resources in the leachate as an effective onsite pre-treatment. Ion-selective membranes were used in this MER to create two different conditions: a low-pH anolyte for organic oxidation and a high-pH catholyte for ammonia recovery. The MER achieved significantly higher removals of both dissolved organic carbon and UV254nm absorbance than membrane-less electrochemical treatment. The MER was able to remove a large percentage of total nitrogen from the leachate while recovering about half of the influent ammonia in the catholyte with less specific energy consumption. The second study coupled MER with Fenton oxidation through providing synergistic benefits with the low solution pH, reduced organics, and ammonia removal. This two-stage coupled system reduced the more leachate COD than the standalone Fenton process treating raw leachate. Also, the usage of chemicals as Fenton reagents has been greatly reduced: FeSO4 and H2O2 by 39%, H2SO4 by 100%, and NaOH by 55%. Consequently, the sludge production was reduced by 51% in weight and 12% in volume. Despite electricity consumption by the MER, the coupled system cost $4.76 per m3 leachate less than the standalone Fenton treatment. More notably, direct Fenton oxidation removed only 21% of ammonia; in comparison, the MER-Fenton system removed ammonia by 98% with the possibility for recovery at a rate of 30.6 -55.2 kg N m-3 reactor d-1. Those results demonstrated that coupling MER with the Fenton process could mitigate some inherent drawbacks of Fenton oxidation such as ineffective ammonia removal, high acid and chemical reagents dose requirements, and a large amount of sludge generation. The third study investigated the formation of total halogenated organics (DBP) and the associated toxicity as the side effect of leachate treatment in the MER. Compared to the 4538±100 µg L-1 from the control membrane-less electrochemical oxidation reactor, the amount of DBP generated in the MER only accounted for 19.1±4.5 % after the same treatment period. The total toxicity value (26.6 ×10-3 ) was low for MER effluent, only 15.1% of that in the control group. Both high pH and high ammonia concentration introduced more DBP mass and toxicity production after MER treatment. DBP concentrations were shown to increase with applied current density and possible temperature raise. With 67.5% of DBP mass concentration and 74.4% of the additive toxicity removal, the granular activated carbon (GAC) electrode system was shown more effective than GAC adsorption alone in remediating DBP harmful effects. This dissertation introduced MER as a promising technology for the treatment of leachate through performance demonstration, process integration and by-product remediation. / Doctor of Philosophy / Municipal solid waste is often disposed of in landfills because of the most economics and convenience. However, one of the most challenging problems is the leachate formation and treatment. In the US, leachate is currently often diluted in domestic wastewater treatment systems; meanwhile, the persistent contaminants in landfill leachate can lower the effectiveness of UV disinfection and result in high cost and permit violation. In this study, the membrane electrochemical reactor (MER) using electricity as the driving force was applied to solve the issue and simultaneously recover valuable resources in the leachate. Membranes as a barrier for selective ions were used in this MER to create two different conditions with different purposes: a low-pH anolyte for organic oxidation and a high-pH catholyte for ammonia recovery. The MER achieved significantly higher contaminants removals than membrane-less electrochemical treatment. The second study coupled MER with one of the established advanced oxidation processes, also known as Fenton oxidation through providing mutual benefits with the low solution pH, reduced organics, and ammonia removal/recovery. This two-stage coupled system reduced the leachate contaminants effectively towards the direct discharge standard. In addition, the usage of chemical reagents, as well as the amount of process residual, has significantly been reduced. The third study investigated the formation of by-products as the side effect of leachate treatment in the MER. Compared to the membrane-less reactor, the undesirable by-products generated in the MER only accounted for one fifth after the same treatment period. A granular activated carbon electrode system was shown effective in remediating the harmful effects. This dissertation introduced MER as a promising technology for the treatment of leachate as one of the toughest wastewaters.

PhD. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / Human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) causes morbidity and mortality in infected patients. These epidemics are significantly reduced and treated globally with antiretroviral drugs (ARVDs). However, the eventual disposal of the ARVDs, either by excretion or otherwise, enables them to end up as emerging hazardous contaminants in our environment. Of all the available methods to remove ARVDs from our water bodies, electrochemical methods are reckoned to be one of the most effective. As a result, it is imperative to acknowledge the interactive behavior of these pharmaceuticals on the surface of the electrode. In this study, iron nano-particles were deposited on the carbon cloth electrode by electrodeposition using chronoamperometry techniques. The synthesized electrode was characterized using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and x-ray photoelectron spectroscopy (XPS) microanalysis. The electrochemical characterization of the material was also carried out using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrode's electrocatalytic activity toward the generation of hydrogen peroxide (H2O2) through a two-electron oxygen reduction reaction was assessed. Furtherance to this is the electrochemical degradation of nevirapine (NVP), lamivudine (LVD), and zidovudine (ZVD) in wastewater as a pharmaceutical model compound for organic pollutants in 50 mM K2SO4 electrolyte at a pH of 3. The SEM and EDX analysis showed the formation of iron nanoparticles within the matrix structure of the carbon cloth (CC) electrode. The XPS enlightened the presence of oxygen functional groups in the electrode's structure. EIS results are indicative that the modified electrode has a decreased charge transfer resistance (Rct)value as compared to the bare CC electrode. On the other hand, the CV result fosters good conductivity, enhanced current and large surface area of the modified electrode. More active and anchor sites were discovered on the iron-supported CC electrode which resulted in higher catalytic activity for the generation and accumulation of H2O2. The concentrations of “in-situ” generated H2O2 were found to be related to the current density supplied to the device after quantification. Although the accumulated H2O2 concentration appears to be low, it's possible that side reactions depleted the amount of H2O2 produced. As a result, the oxygen reduction reaction (ORR) through 2e- has a higher electrocatalytic activity with the improved iron assisted CC electrode than bare CC electrode. The electrochemical degradation studies conducted with the modified CC electrode by electro-Fenton process show a decrease in the initial ARVDs concentration (20 mg/L) as compared with the bare electrode. Their rate constants were 1.52 x 10-3 mol-1min-1 for ZVD, 1.20 x 10-3 mol-1min-1 for NVP and 1.18 x 10-3 mol-1min-1 for LVD. The obtained removal efficiencies indicate that the iron nanoparticle in the synthesised improves the degradation efficiency.

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology / Fenton oxidation is classified into two processes, homogeneous and heterogeneous. Homogeneous Fenton oxidation process, have been shown to be efficient in the degradation of organic pollutants. However, it was shown to have limitations which can be addressed by the heterogeneous Fenton oxidation. Despite the high efficiency of the heterogeneous Fenton oxidation process in the degradation of recalcitrant organic pollutants, the currents synthesis trends of the heterogeneous Fenton catalyst have been proven to be time and energy constraining, since it involves the multi-step were the activated carbon have to be prepared first then co-precipitate the iron oxide on the activated carbon. However, as much as the heterogeneous Fenton catalyst has been proven to have high catalytic activity towards degradation of organic pollutants, these catalysts have some limitations, such limitations include metal ions being leached from the catalyst support into the treated water causing catalyst deactivation and a secondary pollution to the treated water. In this thesis, these catalysts have been applied in the degradation of recalcitrant organic pollutants such as methylene blue and phenols. This study focuses on the single step synthesis of iron oxide nanoparticles supported on activated carbon, were carbonaceous material is impregnated with iron salt then pyrolysed via microwave heating. Microwave power and the amount of iron salt were optimized. The prepared activated carbon-iron oxide composites were applied to the degradation of 2-nitrophenol (2-NP) and methylene blue (MB). Methylene blue was used as a model compound due to the fact that it is easier to monitor the degradation process with UV-Vis as compared to 2-nitrophenol . 2-nitrophenol the additional step for the adjustment of pH is required since nitrophenols are colorless in color at lower pH. The characterization showed that the microwave power and the amount of the iron precursor have an influence on the porosity and surface functional groups of the activated carbon. Further it was vi observed that microwave power and iron precursor influnces the amount of iron oxide formed on the surface of the support. It was also observed that the activated carbon-iron oxide composite have the catalytic effects on the Fenton oxidation process of MB and 2-NP. The parameters such as H2O2, pH, catalyst dose, initial concentration, temperature affect the degradation of both MB and 2-NP. Kinetics studies showed that Fenton is a surface driven reaction since the results fitted the pseudo first order model. The thermodynamics parameters also showed that the reaction is endothermic, spontaneous and is randomized. This implies that the reaction of the degradation of MB and 2-NP is feasible and the catalysts prepared have high catalytic activity. MB and 2-NP were degraded to smaller organic molecules (carboxylic acids). The stability of the catalyst observed to decrease as the number of cycles increased, this is due to the leaching of iron ions from the support material. Hence it was concluded that the activated carbon-iron oxide composite was successfully synthesized and had the high catalytic activity for the degradation of MB and 2-NP.