Adsorption of Acetone / Heptane Gaseous Mixtures on Zeolite Co-Adsorption Equilibria and Selectivities

In the present study, co-adsorption of gaseous n-heptane and acetone is studied. The adsorbent is a commercial hydrophobic zeolite. Breakthrough curves and isotherms are measured for three different acetone/heptane mixture ratios and for pure components. Zeolites showed a greater adsorption capacity for acetone alone than for heptane alone. For the mixtures, the majority component was the most adsorbed. Zeolites have a good selectivity for acetone even though acetone is more volatile than heptane. Specific adsorption sites are reserved for acetone adsorption and are not accessible to heptane. The polarity of a component leads to electrostatic interactions with cation exchange. On non-specific adsorption sites, acetone can be displaced by heptane, which is less volatile. Moreover, experiments show that selectivity depends on the ratio of the mixture. For co-adsorption of a mixture of polar and non-polar components, selectivity depends on relative polarity, mixture ratio, and boiling point

Pilot-scale integrated process for the treatment of dry-spun acrylic fiber manufacturing wastewater

An integrated process of membrane bioreactor (MBR)—advanced ozonation (AO)—biological aerated filters (BAFs) was developed for the treatment of dry-spun acrylic fiber manufacturing wastewater in pilot scale. The results show that the removal efficiencies of chemical oxygen demand (COD) and ammonia nitrogen (-N) could exceed 90.0 and 95.0%, respectively. The COD concentration in the total effluent was maintained at 80.0–100 mg/L, and the -N concentration was below 10.0 mg/L. Both the MBR and BAFs could adapt to the influent of practical wastewater after a period of sludge acclimatization. The removal efficiencies of COD and -N in the MBR were maintained at 65.8–71.9 and 59.4–67.5%, respectively. Excitation–emission matrix spectroscopy confirmed that most of the easy degradable organics were removed in the MBR process. After the AO treatment, COD concentration in the wastewater was reduced by 106–157 mg/L and the biodegradability was enhanced. Simultaneous nitrification–denitrification was performed in the biofilm of BAFs, and the removal efficiency of total nitrogen was in the range of 58.2–71.6% after the entire integrated process

Catalytic ozonation with γ-Al2O3 to enhance the degradation of refractory organics in water

Nowadays, heterogeneous catalytic ozonation appears as a promising way to treat industrial wastewaters containing refractory pollutants, which resist to biological treatments. Several oxides and minerals have been used and their behavior is subject to controversy with particularly the role of Lewis acid sites and/or basic sites and the effect of salts. In this study, millimetric mesoporous γ-Al2O3 particles suitable for industrial processes were used for enhancing the ozonation efficiency of petrochemical effluents without pH adjustment. A phenol (2,4-dimethylphenol (2,4-DMP)) was first chosen as petrochemical refractory molecule to evaluate the influence of alumina in ozonation. Single ozonation and ozonation in presence of γ-Al2O3 led to the disappearance of 2,4-DMP in 25 min and a decrease in pH from 4.5 to 2.5. No adsorption of 2,4-DMP occurred on γ-Al2O3. Adding γ-Al2O3 in the process resulted in an increase of the 2,4–DMP oxidation level. Indeed, the total organic carbon (TOC) removal was 14% for a single ozonation and 46% for ozonation with γ-Al2O3. Similarly, chemical oxygen demand (COD) removal increases from 35 to 75%, respectively. Various oxidized by-products were produced during the degradation of 2,4-DMP, but after 5 h ozonation 90% of organic by-products were acetic acid > formic acid ≫ oxalic acid. Some of the carboxylic acids were adsorbed on γ-Al2O3. The use of radical scavengers (tert-butanol) highlighted the involvement of hydroxyl radicals during catalytic ozonation with γ-Al2O3 in contrary to single ozonation, which mainly involved direct ozone reaction. γ-Al2O3 is an amphoteric solid with Lewis acid AlOH(H+) sites and basicAl-OH sites. After ozonation the amount of basic sites decreased due to carboxylates adsorption, while the Lewis acid sites remained constant as evidenced by FTIR. Several ozonation runs with γ-Al2O3 reported a progressive decrease of its catalytic activity due to the cumulative sorption of carboxylates on the basic sites. After 80 h of ozonation, a calcination at 550 °C allowed to recover allAl-OH basic sites and the initial activity of γ-Al2O3. A synthetic petrochemical effluent containing various petrochemicals (phenol, acetic acid, naphtenic acid, pyrene, naphtalene) was then treated with γ-Al2O3 with and without NaCl. Sodium ions prevented carboxylates adsorption on γ-Al2O3 leading to a higher efficiency of γ-Al2O3 in presence of NaCl and allowed to decrease the toxicity of the petrochemical effluent

Rôle des paramètres opératoires sur la fiabilité d une analyse multi-résidus de micropolluants dans l eau (extraction sur phase solide, séparation par chromatographie liquide à très haute pression et détection par spectrométrie de masse en tandem)

La présence de micropolluants est un aspect majeur pour évaluer la qualité des eaux. Depuis quelques années les méthodes analytiques combinant l extraction sur phase solide et la séparation par chromatographie liquide couplée à la détection par spectrométrie de masse en tandem se sont imposées pour mesurer une large gamme de micropolluants. A partir d un exemple d analyse multi-résidus de pesticides et de composés perturbateurs endocriniens dans les eaux, il a été recherché l influence des différents paramètres de l extraction, de la séparation, de la détection et du retraitement des données sur la qualité de l analyse (répétabilité, fiabilité, stabilité, reproductibilité ). Chacune des étapes de la méthode d analyse ont été optimisées et tous les paramètres qui influencent le signal des substances détectées avec ce type d appareillage ont été discutés. Une réflexion globale sur l origine des variations des signaux observées et sur la pertinence des solutions qui peuvent être apportées a été menée. Des exemples d applications en milieu réel et en analyse inter-laboratoire des protocoles développés pour la mesure des pesticides valideront les solutions adoptées. Les clés et les outils permettant de maîtriser les résultats d analyse des micropolluants dans l eau par chromatographie liquide couplée à la spectrométrie de masse sont ainsi présentés dans ce travail.The occurrence of micropollutants is a major aspect in water quality assessment. For the last few years, analytical methods combining solid-phase extraction, liquid chromatography and tandem mass spectrometry has become the main technique for the analysis of a broad range of micropollutants. On the basis of some pesticides and endocrine disruptor compounds in water analysis, impacts of the parameters: extraction, separation, detection and data processing, on the analysis reliability (repeatability, accuracy, stability, reproducibility ) have been studied. Each step of the analytical method has been optimized and the parameters, affecting substance signals have been discussed. A global reflection upon the cause of signal variations and the possible answers to apply has been conducted. Proposed answers were validated by real matrix analysis and inter-laboratory studies. This work presents the tools and the key-points to ensure the results obtained by liquid chromatography/tandem mass spectrometry analysis.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Etude des méthodes d'élaboration et de la mise en oeuvre de photocatalyseurs pour le traitement de la micro pollution bio-réfractaire dans l'eau

Ce travail de thèse est consacré à l'élaboration de membrane photocatalytique à partir de nanoparticules de TiO2 obtenues par voie sol-gel (système TTIP-eau). Les sols sont préparés dans un réacteur à micro-mélange rapide (turbulent). L'effet de l'hydrodynamique au sein de différents mélangeurs (T simple, T chicanes, T rétrécissement) sur la morphologie et l'activité photocatalytique de nanoparticules déposées sur des plaques d'a-alumine a été étudié. Les dépôts de TiO2 ont été réalisés durant la période d'induction de la réaction sol-gel. Le mélange des réactifs a été simulé en utilisant un logiciel de modélisation numérique (modèle k- ), Les différences hydrodynamiques au sein du micro-mélange a seulement un impact significatif sur le temps de stabilité des nanoparticules (période d'induction). Des couches minces et des membranes photo-actives ont été réalisées en vue du couplage membrane et réaction photocatalytique. Ces membranes ont été caractérisées et testées en photocatalyse. Elles ont montrées de bonnes photo-activités. Des tests de couplage direct séparation/photodégradation ont été réalisés sur des solutions aqueuses d'acide orange 7. Ce dispositif expérimental a permis de mettre en évidence une augmentation de flux de perméation significative avec de l'eau et en présence de colorant en solution. L'effet de la concentration et du pH de la solution a été évalué sur les flux de perméat et sur la photodégradation.This PhD work is devoted to the elaboration of photocatalytic membranes using TiO2 nanoparticles synthetized by sol-gel process (titanium tetra-isopropoxyde precursor water). Sols are prepared in sol-gel reactor with rapid turbulent micro-mixing. The effect of hydrodynamic using 3 T mixers (T simple, T with 3 baffles and T with narrow) during the mixing was studied with k- modeling Computational fluid Dynamics (CFD), as well as the morphology and the photo-activity of thin layers deposited on alumina support during induction period. Differences on hydrodynamic during micro-mixing have only impact on the time of nanoparticles stability (induction period). Photo-active thin layers and membranes are synthesized for coupling membrane separation and photocatalytic reaction. Photocatalytic activities of thin layers and membranes are performed with an aqueous solution of acid orange 7. Significant increases of permeate flux are observed during the filtration of water and solution containing dye. Effects of concentration and pH are evaluated on permeation flux and photodegradation.MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Dégradation de produits phytosanitaires par photocatalyse sur support (application aux effluents agricoles)

La photocatalyse TiO2/UV est une technologie émergente qui peut permettre le traitement des effluents agricoles contenant des pesticides. La première étape a consisté à étudier la dégradabilité et la minéralisation de neuf pesticides sur un réacteur à film tombant. Le devenir de certaines de ces molécules, et en particulier celui des hétéroatomes (chlore, azote, phosphore) a été déterminé. Un effet inhibiteur de la dégradation par les ions phosphate a été mis en évidence. Une interdépendance entre l'intensité lumineuse et la concentration initiale en polluant a été observée et un modèle d'interaction est suggéré. Un modèle décrivant la dégradation et la minéralisation de polluants organiques sur un réacteur à film tombant est proposé. Un ajustement satisfaisant aux données expérimentales sur la durée complète des expériences a été obtenu. Enfin, l'étude de la dégradation d'effluents agricoles nous a permis de confirmer l'intérêt du procédé pour une application industrielle.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Functionalized ceramic nanofilter for wastewater treatment by coupling membrane separation and catalytic ozonation

International audienceMicropollutants elimination in water becomes a global concern and represents an important issue for a possible reuse or a release to the environment. Hybrid processes combining membrane filtration and catalytic ozonation offer promising opportunities for micropollutant removal. A ceramic commercial nanofilter with a very low molecular weight cutoff of 200 Da was functionalized by sol-gel deposition of a mesoporous maghemite (γ-Fe 2 O 3) thin layer. Preliminary experiments enabled to determine the maximum temperature usable for the thermal strengthening of the catalytic layer without significant permeance change. The catalytic activity of the iron oxide equivalent powder was tested in batch reactor with ozone and para-chlorobenzoic acid (pCBA) which quickly reacts with hydroxyl radicals formed with ozone at the catalyst surface, and only very slowly with ozone itself. The operational performance of the functionalized ceramic membrane was evaluated in a dedicated pilot. The obtained results unequivocally show the catalytic activity of this functionalized membrane