Peroxisome Proliferator-Activated Receptor beta/delta in the Brain: Facts and Hypothesis.

peroxisome proliferator-activated receptors (PPARs) are nuclear receptors acting as lipid sensors. Besides its metabolic activity in peripheral organs, the PPAR beta/delta isotype is highly expressed in the brain and its deletion in mice induces a brain developmental defect. Nevertheless, exploration of PPARbeta action in the central nervous system remains sketchy. The lipid content alteration observed in PPARbeta null brains and the positive action of PPARbeta agonists on oligodendrocyte differentiation, a process characterized by lipid accumulation, suggest that PPARbeta acts on the fatty acids and/or cholesterol metabolisms in the brain. PPARbeta could also regulate central inflammation and antioxidant mechanisms in the damaged brain. Even if not fully understood, the neuroprotective effect of PPARbeta agonists highlights their potential benefit to treat various acute or chronic neurological disorders. In this perspective, we need to better understand the basic function of PPARbeta in the brain. This review proposes different leads for future researches.

Ligands for pheromone-sensing neurons are not conformationally activated odorant binding proteins.

Pheromones form an essential chemical language of intraspecific communication in many animals. How olfactory systems recognize pheromonal signals with both sensitivity and specificity is not well understood. An important in vivo paradigm for this process is the detection mechanism of the sex pheromone (Z)-11-octadecenyl acetate (cis-vaccenyl acetate [cVA]) in Drosophila melanogaster. cVA-evoked neuronal activation requires a secreted odorant binding protein, LUSH, the CD36-related transmembrane protein SNMP, and the odorant receptor OR67d. Crystallographic analysis has revealed that cVA-bound LUSH is conformationally distinct from apo (unliganded) LUSH. Recombinantly expressed mutant versions of LUSH predicted to enhance or diminish these structural changes produce corresponding alterations in spontaneous and/or cVA-evoked activity when infused into olfactory sensilla, leading to a model in which the ligand for pheromone receptors is not free cVA, but LUSH that is "conformationally activated" upon cVA binding. Here we present evidence that contradicts this model. First, we demonstrate that the same LUSH mutants expressed transgenically affect neither basal nor pheromone-evoked activity. Second, we compare the structures of apo LUSH, cVA/LUSH, and complexes of LUSH with non-pheromonal ligands and find no conformational property of cVA/LUSH that can explain its proposed unique activated state. Finally, we show that high concentrations of cVA can induce neuronal activity in the absence of LUSH, but not SNMP or OR67d. Our findings are not consistent with the model that the cVA/LUSH complex acts as the pheromone ligand, and suggest that pheromone molecules alone directly activate neuronal receptors.

Activité physique et prévention de l'athérosclérose : mise en évidence de l'implication des PPAR (Peroxisome Proliferaor-Activated Receptor) dans la cardioprotection induite par l'exercice physique soumis ou volontaire chez la souris ApoE-/-.

L'athérosclérose est un processus inflammatoire chronique à l'origine des accidents cardiovasculaires qui constitue l'une des premières causes de mortalité en France. L'inflammation est le facteur essentiel dans l'initiation, la progression et l'instabilité des lésions athéromateuses à l'origine des accidents aigus. Les données récentes suggèrent que l'activation des récepteurs nucléaires PPAR (Peroxysome-Proliferator Activated Receptor) par des ligands pharmacologiques prévient le développement et la progression de l'athérosclérose et diminue de manière importante la mortalité cardiovasculaire. À côté de ces traitements pharmacologiques, l'exercice physique prévient aussi la mortalité cardiovasculaire de manière significative. L'objectif de notre premier travail a été d'explorer les effets de l'exercice physique de natation, sur le déve¬loppement des lésions athéromateuses d'une part et d'autre part, sur l'expression des récepteurs nucléaires PPAR. Nos résultats montrent que l'exercice physique de natation diminue la progression de l'athérosclérose et stimule l'expression des PPAR-γ vasculaires. De manière intéressante, lorsque le PPAR-γ est inhibé avec l'antagoniste BADGE, les effets antiathérogènes de l'exercice physique sont abolis. L'hypertension est à l'origine des complications graves telles que la rupture de plaque d'athérosclérose. L'objectif de notre deuxième travail a été d'explorer l'implication des PPAR dans la progression et la stabilité des lésions athéromateuses chez des souris ApoE-/- hypercholestérolemiques et hypertendues (2K1C), soumises à des exercices physiques (volontaire ou imposé) ou traités avec le telmisartan, un antihypertenseur. Nos résultats montrent que l'exercice physique possède différents mécanismes protecteurs. De manière similaire, l'exercice physique favorise la stabilité de lésions athéromateuses de manière comparable au traitement pharmacologique. De plus, nos résultats montrent que les souris traitées avec l'exercice imposé ou le telmisartan présentent un mécanisme comparable qui permet de réduire significativement l'expression des cytokines pro-inflammatoire et d'activer les PPAR-γ vasculaires. L'exercice volontaire favorise l'expression des marqueurs des macrophages alternatifs M2 et des cytokines anti-inflammatoires (CD 206, IL-1 Ra). L'exercice volontaire diminue significativement l'extension des lésions athéromateuses de manière comparable au telmisartan. Ces résultats montrent que l'exercice physique volontaire et l'exercice physique imposé ont deux mécanismes d'actions distincts. De plus, la surexpression des M2 en réponse à l'exercice volontaire modifie la balance inflammatoire en faveur des M2. Ce renversement de la balance au profit des macrophages alternatifs M2 est significativement corrélé à la diminution de la progression des lésions athéromateuses. Les exercices imposé et volontaire possèdent des mécanismes d'action distincts. L'exercice soumis diminue l'expression des cytokines pro-inflammatoires tandis que l'exercice volontaire augmente l'expression des cytokines anti-inflammatoires et favorise un phénotype anti-inflammatoire des macrophages M2 qui s'accompagne d'une réduction des lésions athéromateuses. - Atherosclerosis is a complex inflammatory process, leading cause of morbidity and mortality in France. Inflammation is essential in initiation, progression and atherosclerosis plaque destabilization leading to acute cardiovascular events. Recent studies suggest that pharmacological PPAR activation prevents ΑΤΗ développement and progression and decreased cardiovascular mortality. Compared to pharmacological treatment, physical exercise also significantly prevents cardiovascular mortality. The aim of the first study was to investigate the influence of physical exercise on ATS development and PPAR expression in arterial wall. Our results had shown that physical exercise decrease ΑΤΗ progression and increase PPAR-γ expression in arterial wall. Interestingly, PPAR-γ inhibition with BADGE, a PPAR-γ antagonist abolishes these antiatherogenic effects. Hypertension increase ΑΤΗ complication such as plaque rupture. The aim of the second study were to inves¬tigate PPAR-γ implication in progression and stabilization of ΑΤΗ lesions in hypercholesterolemic and hypertensive ApoE-/- mice (2K1C) submitted to different exercises (voluntary wheel running and submitted treadmill running) or treated with telmisartan an anti-hypertensive drug. Our results shown that, physical exercise prevents ATS cardiovascular events by several mechanisms. Similarly to telmisartan, physical exercises stabilize ΑΤΗ lesion. Moreover results shown that, submitted exercise and telmisartan have an comparable mechanism. In fact, they significantly decrease pro-inflammatory cytokines expression and in the same time activated PPAR-γ expression in arterial wall. Contrary to submitted exercise, voluntary exercises increases expression of anti-inflammatory cytokines IL-1ra and increase M2 marker CD206. These results suggest that voluntary and submitted exercise have two different mechanism of action. Moreover, M2 surexpression in response to voluntary exercise shift the inflammatory balance in favor to M2. Further, this change of balance in favor to M2, is significantly correlated to decrease of ΑΤΗ progression. Voluntary exercises significantly decreases ΑΤΗ progression in the same levels like telmisartan treatment. Voluntary and submitted exercise has two different mechanisms, submitted exercise decrease proinflammatory cytokines expression whereas voluntary exercise increase anti-inflammatory cytokines expression and promote an anti-inflammatory phenotype of macrophages M2. The shift of M1/M2 balance towards M2 decreases atherosclerosis progression.

Gold recovery from cyanideand chloride solution using activated carbon

Uusia keinoja kullan erottamiseksi malmista on etsitty viimeaikoina taloudellisista ja ympäristöllisistä syistä kautta maailman. Syanidointimenetelmä on hallinnut kullan talteenottoayli sata vuotta. Menetelmässä kulta liuotetaan laimeaan syanidiliuokseen, jostase otetaan talteen aktiivihiilen avulla. Syanidin käyttöä pyritään kuitenkin vähentämään sen myrkyllisyyden takia. Lisäksi nykyään louhitaan enenemässä määrin malmia, josta on hankala rikastaa kulta kustannustehokkaasti syanidia käyttäen. Kullan talteenottoa syanidi- ja kloridiliuoksesta on selvitetty kirjallisuuden avulla. Kullan kemiaan liuotuksen aikana on perehdytty ennen kullan talteenottoa aktiivihiilellä. Aktiivihiilen elinkaari kullan adsorbenttinaon käsitelty valmistuksesta hylkäämiseen mukaan lukien hiilen myrkyttyminen prosessissa ja regenerointi. Aktiivi-hiilen käyttäytyminen syanidi- ja kloridiliuoksessa on selvitetty erikseen. Kullan talteenottoa kuparipitoisista malmeista on käsitelty. Kullan talteenottoa kloridiliuoksesta aktiivihiiltä käyttäen on tutkittu kokeellisesti. Pääasialliset tutkimuskohteet ovat adsorption kinetiikka, kuparin vaikutus adsorptioon, aktiivihiilen vaikutus adsorptioonja adsorboituneiden metallien strippaus hiilestä selektiivisesti. Hapettavan stippauksen vaikutus kullan desorptioon hiilestä on tutkittu yksityiskohtaisesti. Kullan erotusmenetelmät kuparimalmista aktiivihiiltä käyttäen on selvitetty diplomityön tulosten pohjalta. Diplomityön keskeisten tulosten perusteella kulta ei välttämättä saostu aktiivihiilen pinnalle kloridiliuoksesta. Havainto varmistettiin ladattujen hiilipartikkelien pyyhkäisyelektronimikroskooppikuvista ja partikkeleille tehdyistä mikroanalyyseistä. Kullan pelkistyminen metalliseksi kullaksi aktiivihiilessä voitaneen välttää käyttämällä erittäin hapettavia olosuhteita. Aktiivihiili ilmeisesti hapettuu näissä olosuhteissa, mikä mahdollistaa kultakloridin adsorboitumisen hiileen.

Wet Oxidation of Concentrated Wastewaters: Process Combination and Reaction Kinetic Modeling

The accumulation of aqueous pollutants is becoming a global problem. The search for suitable methods and/or combinations of water treatment processes is a task that can slow down and stop the process of water pollution. In this work, the method of wet oxidation was considered as an appropriate technique for the elimination of the impurities present in paper mill process waters. It has been shown that, when combined with traditional wastewater treatment processes, wet oxidation offers many advantages. The combination of coagulation and wet oxidation offers a new opportunity for the improvement of the quality of wastewater designated for discharge or recycling. First of all, the utilization of coagulated sludge via wet oxidation provides a conditioning process for the sludge, i.e. dewatering, which is rather difficult to carry out with untreated waste. Secondly, Fe2(SO4)3, which is employed earlier as a coagulant, transforms the conventional wet oxidation process into a catalytic one. The use of coagulation as the post-treatment for wet oxidation can offer the possibility of the brown hue that usually accompanies the partial oxidation to be reduced. As a result, the supernatant is less colored and also contains a rather low amount of Fe ions to beconsidered for recycling inside mills. The thickened part that consists of metal ions is then recycled back to the wet oxidation system. It was also observed that wet oxidation is favorable for the degradation of pitch substances (LWEs) and lignin that are present in the process waters of paper mills. Rather low operating temperatures are needed for wet oxidation in order to destruct LWEs. The oxidation in the alkaline media provides not only the faster elimination of pitch and lignin but also significantly improves the biodegradable characteristics of wastewater that contains lignin and pitch substances. During the course of the kinetic studies, a model, which can predict the enhancements of the biodegradability of wastewater, was elaborated. The model includes lumped concentrations suchas the chemical oxygen demand and biochemical oxygen demand and reflects a generalized reaction network of oxidative transformations. Later developments incorporated a new lump, the immediately available biochemical oxygen demand, which increased the fidelity of the predictions made by the model. Since changes in biodegradability occur simultaneously with the destruction of LWEs, an attempt was made to combine these two facts for modeling purposes.

Aluminium fouling and its impact on activated carbon based dioxin and furan removal in a wet scrubber at a co-incineration plant

Dioxins and furans, PCDD/Fs, are highly toxic substances formed in post combustion zones in furnaces. PCDD/F emissions are regulated by a waste incineration directive which relates also to co-incineration plants. Several observations of dioxin and furan enhancements in wet scrub- bers have been reported previously. This is thought to be due to the so-called "memory effect" which occurs when dioxins and furans absorb into plastic material in scrubbers and desorb when ambient circumstances alter significantly. At the co-incineration plant involved, dioxins and furans are controlled with a wet scrubber, the tower packing of which is made of plastic in which activated carbon particles are dispersed. This should avoid the memory effect and act as a dioxin and furan sink since dioxins and furans are absorbed irreversibly into the packing ma- terial. In this case, the tower packing in the scrubber is covered with a white layer that has been found to be mainly aluminium. The aim of this thesis was to determine the aluminium balance and the dioxin and furan behaviour in the scrubber and, thus, the impacts that the foul- ing has on dioxin and furan removal. The source of aluminium, reasons for fouling and further actions to minimize its impacts on dioxin and furan removal were also to be discovered. Measurements in various media around the scrubber and in fuels were made and a profile analysis of PCDD/F and mass balance calculations were carried out. PCDD/F content de- creased in the scrubber. The reduced PCDD/F was not discharged into scrubbing water. The removal mechanism seems to work in spite of the fouling, at least with low PCDD/F loads. Most of the PCDD/F in excess water originates from the Kymijoki River which is used as feeding water in the scrubber. Fouling turned out to consist mainly of aluminium hydroxides. Sludge combusted in the furnace was found to be a significant source of aluminium. Ways to minimize the fouling would be adjustment of pH to a proper lever, installation of a mechanical filter to catch the loose material from the scrubbing water and affecting the aluminium content of the sludge.

T Cell Priming by Activated Nlrc5-Deficient Dendritic Cells Is Unaffected despite Partially Reduced MHC Class I Levels.

NLRC5, a member of the NOD-like receptor (NLR) protein family, has recently been characterized as the master transcriptional regulator of MHCI molecules in lymphocytes, in which it is highly expressed. However, its role in activated dendritic cells (DCs), which are instrumental to initiate T cell responses, remained elusive. We show in this study that, following stimulation of DCs with inflammatory stimuli, not only did NLRC5 level increase, but also its importance in directing MHCI transcription. Despite markedly reduced mRNA and intracellular H2-K levels, we unexpectedly observed nearly normal H2-K surface display in Nlrc5(-/-) DCs. Importantly, this discrepancy between a strong intracellular and a mild surface defect in H2-K levels was observed also in DCs with H2-K transcription defects independent of Nlrc5. Hence, alongside with demonstrating the importance of NLRC5 in MHCI transcription in activated DCs, we uncover a general mechanism counteracting low MHCI surface expression. In agreement with the decreased amount of neosynthesized MHCI, Nlrc5(-/-) DCs exhibited a defective capacity to display endogenous Ags. However, neither T cell priming by endogenous Ags nor cross-priming ability was substantially affected in activated Nlrc5(-/-) DCs. Altogether, these data show that Nlrc5 deficiency, despite significantly affecting MHCI transcription and Ag display, is not sufficient to hinder T cell activation, underlining the robustness of the T cell priming process by activated DCs.

Macroautophagic process was differentially modulated by long-term moderate exercise in rat brain and peripheral tissues

The autophagic process is a lysosomal degradation pathway, which is activated during stress conditions, such as starvation or exercise. Regular exercise has beneficial effects on human health, including neuroprotection. However, the cellular mechanisms underlying these effects are incompletely understood. Endurance and a single bout of exercise induce autophagy not only in brain but also in peripheral tissues. However, little is known whether autophagy could be modulated in brain and peripheral tissues by long-term moderate exercise. Here, we examined the effects on macroautophagy process of long-term moderate treadmill training (36 weeks) in adult rats both in brain (hippocampus and cerebral cortex) and peripheral tissues (skeletal muscle, liver and heart). We assessed mTOR activation and the autophagic proteins Beclin 1, p62, LC3B (LC3B-II/LC3B-I ratio) and the lysosomal protein LAMP1, as well as the ubiquitinated proteins. Our results showed in the cortex of exercised rats an inactivation of mTOR, greater autophagy flux (increased LC3-II/LC3-I ratio and reduced p62) besides increased LAMP1. Related with these effects a reduction in the ubiquitinated proteins was observed. No significant changes in the autophagic pathway were found either in hippocampus or in skeletal and cardiac muscle by exercise. Only in the liver of exercised rats mTOR phosphorylation and p62 levels increased, which could be related with beneficial metabolic effects in this organ induced by exercise. Thus, our findings suggest that long-term moderate exercise induces autophagy specifically in the cortex

Macroautophagic process was differentially modulated by long-term moderate exercise in rat brain and peripheral tissues

The autophagic process is a lysosomal degradation pathway, which is activated during stress conditions, such as starvation or exercise. Regular exercise has beneficial effects on human health, including neuroprotection. However, the cellular mechanisms underlying these effects are incompletely understood. Endurance and a single bout of exercise induce autophagy not only in brain but also in peripheral tissues. However, little is known whether autophagy could be modulated in brain and peripheral tissues by long-term moderate exercise. Here, we examined the effects on macroautophagy process of long-term moderate treadmill training (36 weeks) in adult rats both in brain (hippocampus and cerebral cortex) and peripheral tissues (skeletal muscle, liver and heart). We assessed mTOR activation and the autophagic proteins Beclin 1, p62, LC3B (LC3B-II/LC3B-I ratio) and the lysosomal protein LAMP1, as well as the ubiquitinated proteins. Our results showed in the cortex of exercised rats an inactivation of mTOR, greater autophagy flux (increased LC3-II/LC3-I ratio and reduced p62) besides increased LAMP1. Related with these effects a reduction in the ubiquitinated proteins was observed. No significant changes in the autophagic pathway were found either in hippocampus or in skeletal and cardiac muscle by exercise. Only in the liver of exercised rats mTOR phosphorylation and p62 levels increased, which could be related with beneficial metabolic effects in this organ induced by exercise. Thus, our findings suggest that long-term moderate exercise induces autophagy specifically in the cortex

Evaluation of sample processing methods for the polar contaminant analysis of sewage sludge using liquid chromatography - mass spectrometry (LC/MS)

Monitoring of sewage sludge has proved the presence of many polar anthropogenic pollutants since LC/MS techniques came into routine use. While advanced techniques may improve characterizations, flawed sample processing procedures, however, may disturb or disguise the presence and fate of many target compounds present in this type of complex matrix before analytical process starts. Freeze-drying or oven-drying, in combination with centrifugation or filtration as sample processing techniques were performed followed by visual pattern recognition of target compounds for assessment of pretreatment processes. The results shown that oven-drying affected the sludge characterization, while freeze-drying led to less analytical misinterpretations.

Removal of Pb(II) ions and malachite green dye from wastewater by activated carbon produced from lemon peel

In the present study, a high-surface area activated carbon was prepared by chemical activation of lemon peel with H3PO4 as the active agent. Then, the adsorption behavior of Malachite green dye and Pb(II) ions on the produced activated carbon was studied. Batch process was employed for sorption kinetics and equilibrium studies. Experimental data were fitted to various isotherm models. According to the Langmuir model, the maximum adsorption capacities of Malachite green dye and Pb(II) ions were found to be 66.67 and 90.91 mg g-1, respectively, at room temperature. Kinetic studies showed the adsorption process followed a pseudo second-order rate model. The sorption kinetics were controlled by intra-particle diffusion. The results indicated that the produced activated carbon can be economically and effectively used as an adsorbent for the removal of Malachite green dye and Pb(II) ions from wastewaters.

The Methods of Possible Joint Treatment of Manure and Sewage Sludge in the Leningrad Region

The nutrient load to the Gulf of Finland has started to increase as a result of the strong economic recovery in agriculture and livestock farming in the Leningrad region. Also sludge produced from municipal wastewater treatment plant of the Leningrad region causes the great impact on the environment, but still the main options for its treatment is disposal on the sludge beds or Landfills. The aim of this study was to evaluate the implementation of possible joint treatment methods of manure form livestock and poultry enterprises and sewage sludge produced from municipal wastewater treatment plants in the Leningrad region. The study is based on published data. The most attention was put on the anaerobic digestion and incineration methods. The manure and sewage sludge generation for the whole Leningrad region and energy potential produced from their treatment were estimated. The calculations showed that total amount of sewage sludge generation is 1 348 000 t/a calculated on wet matter and manure generation is 3 445 000 t/a calculated on wet matter. The potential heat release from anaerobic digestion process and incineration process is 4 880 000 GJ/a and 5 950 000 GJ/a, respectively. Furthermore, the work gives the overview of the general Russian and Finnish legislation concerning manure and sewage sludge treatment. In the Gatchina district it was chosen the WWTP and livestock and poultry enterprises for evaluation of the centralized treatment plant implementation based on anaerobic digestion and incineration methods. The electricity and heat power of plant based on biogas combustion process is 4.3 MW and 7.8 MW, respectively. The electricity and heat power of plant based on manure and sewage sludge incineration process is 3.0 MW and 6.1 MW, respectively.

Sewage Sludge Electro-Dewatering

Original sludge from wastewater treatment plants (WWTPs) usually has a poor dewaterability. Conventionally, mechanical dewatering methods are used to increase the dry solids (DS) content of the sludge. However, sludge dewatering is an important economic factor in the operation of WWTPs, high water content in the final sludge cake is commonly related to an increase in transport and disposal costs. Electro‐dewatering could be a potential technique to reduce the water content of the final sludge cake, but the parameters affecting the performance of electro‐dewatering and the quality of the resulting sludge cake, as well as removed water, are not sufficiently well known. In this research, non‐pressure and pressure‐driven experiments were set up to investigate the effect of various parameters and experimental strategies on electro‐dewatering. Migration behaviour of organic compounds and metals was also studied. Application of electrical field significantly improved the dewatering performance in comparison to experiments without electric field. Electro‐dewatering increased the DS content of the sludge from 15% to 40 % in non‐pressure applications and from 8% to 41% in pressure‐driven applications. DS contents were significantly higher than typically obtained with mechanical dewatering techniques in wastewater treatment plant. The better performance of the pressure‐driven dewatering was associated to a higher current density at the beginning and higher electric field strength later on in the experiments. The applied voltage was one of the major parameters affecting dewatering time, water removal rate and DS content of the sludge cake. By decreasing the sludge loading rate, higher electrical field strength was established between the electrodes, which has a positive effect on an increase in DS content of the final sludge cake. However interrupted voltage application had anegative impact on dewatering in this study, probably because the off‐times were too long. Other factors affecting dewatering performance were associated to the original sludge characteristics and sludge conditioning. Anaerobic digestion of the sludge with high pH buffering capacity, polymer addition and freeze/thaw conditioning had a positive impact on dewatering. The impact of pH on electro‐dewatering was related to the surface charge of the particles measured as zeta‐potential. One of the differences between electro‐dewatering and mechanical dewatering technologies is that electro‐dewatering actively removes ionic compounds from the sludge. In this study, dissolution and migration of organic compounds (such as shortchain fatty acids), macro metals (Na, K, Ca, Mg, Fe) and trace metals (Ni, Mn, Zn, Cr) was investigated. The migration of the metals depended on the fractionation and electrical field strength. These compounds may have both negative and positive impacts on the reuse and recycling of the sludge and removed water. Based on the experimental results of this study, electro‐dewatering process can be optimized in terms of dewatering time, desired DS content, power consumption and chemical usage.

Wastewater Treatment and Deinking Sludge Utilization Possibilities for Energy and Material Recovery in the Leningrad Region

Operation of pulp and paper mills generates waste including wastewater treatment sludge and deinking sludge. Both sludge types are generated in large amounts and are mainly disposed of in landfills in the Leningrad Region resulting in environmental degradation. The thesis was aimed at seeking new sustainable ways of sludge utilization. Two paper mills operating in the Leningrad Region and landfilling their sludge were identified: “SCA Hygiene Products Russia” and “Knauf”. The former generates 150 t/day of deinking sludge, the latter – 145 t/day of secondary sludge. Chemical analyses of deinking sludge were performed to assess applicability of sludge in construction materials production processes. Higher heating value on dry basis of both sludge types was determined to evaluate energy potential of sludge generated in the Leningrad Region. Total energy output from sludge incineration was calculated. Deinking sludge could be utilized in the production process of “LSR-Cement” or “Slantsy Cement Plant Cesla” factories, and “Pobeda” and “Nikolsky” brick mills without exceeding current sludge management costs.

Development of a process for the direct synthesis of hydrogen peroxide in a novel microstructured reactor

Microreactors have proven to be versatile tools for process intensification. Over recent decades, they have increasingly been used for product and process development in chemical industries. Enhanced heat and mass transfer in the reactors due to the extremely high surfacearea- to-volume ratio and interfacial area allow chemical processes to be operated at extreme conditions. Safety is improved by the small holdup volume of the reactors and effective control of pressure and temperature. Hydrogen peroxide is a powerful green oxidant that is used in a wide range of industries. Reduction and auto-oxidation of anthraquinones is currently the main process for hydrogen peroxide production. Direct synthesis is a green alternative and has potential for on-site production. However, there are two limitations: safety concerns because of the explosive gas mixture produced and low selectivity of the process. The aim of this thesis was to develop a process for direct synthesis of hydrogen peroxide utilizing microreactor technology. Experimental and numerical approaches were applied for development of the microreactor. Development of a novel microreactor was commenced by studying the hydrodynamics and mass transfer in prototype microreactor plates. The prototypes were designed and fabricated with the assistance of CFD modeling to optimize the shape and size of the microstructure. Empirical correlations for the mass transfer coefficient were derived. The pressure drop in micro T-mixers was investigated experimentally and numerically. Correlations describing the friction factor for different flow regimes were developed and predicted values were in good agreement with experimental results. Experimental studies were conducted to develop a highly active and selective catalyst with a proper form for the microreactor. Pd catalysts supported on activated carbon cloths were prepared by different treatments during the catalyst preparation. A variety of characterization methods were used for catalyst investigation. The surface chemistry of the support and the oxidation state of the metallic phase in the catalyst play important roles in catalyst activity and selectivity for the direct synthesis. The direct synthesis of hydrogen peroxide was investigated in a bench-scale continuous process using the novel microreactor developed. The microreactor was fabricated based on the hydrodynamic and mass transfer studies and provided a high interfacial area and high mass transfer coefficient. The catalysts were prepared under optimum treatment conditions. The direct synthesis was conducted at various conditions. The thesis represents a step towards a commercially viable direct synthesis. The focus is on the two main challenges: mitigating the safety problem by utilization of microprocess technology and improving the selectivity by catalyst development.