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Spreutels L.,Eng-Tips | Haut B.,Free University of Colombia | Legros R.,QC H3T 1J4Canada | Bertrand F.,QC H3T 1J4Canada | Chaouki J.,QC H3T 1J4Canada
AIChE Journal | Year: 2015

Solid particles flow in a conical spouted bed is characterized by radioactive particle tracking. The influence of operating conditions on key parameters of this flow is evaluated and discussed: the morphology of the solid bed is not strongly influenced by the forces exerted by the gas on the solid particles, but rather by geometrical considerations; the particles spend approximately 8% of their time in the spout in all experiments; it is the force exerted on the solid particles by the gas that directly controls the volumetric flow rate between adjacent regions, and not the amount of particles in the bed; as U/Ums increases, the volume of solid particles in the annulus decreases, the volume of solid particles in the fountain increases and the volume of solid particles in the spout remains constant. Correlations to predict key flow parameters as functions of operating conditions are also established and discussed. © 2015 American Institute of Chemical Engineers.


Aguilar-Galvez A.,Agrarian National University | Noratto G.,Washington State University | Chambi F.,Agrarian National University | Chambi F.,Eng-Tips | And 2 more authors.
Food Chemistry | Year: 2014

Gallotannins obtained from tara pod extracts (EE) and from the products of acid hydrolysis for 4 and 9 h (HE-4 and HE-9) were characterised for their composition, antioxidant activity, antimicrobial activity (AA) and minimum inhibitory concentration (MIC). Results of AA and MIC showed that EE exerted the highest inhibitory activity against Staphylococcus aureus, followed by Pseudomonas fluorescens; and among these bacteria, the antibacterial potency was enhanced after EE hydrolysis only against S. aureus. The lowest minimum inhibitory concentration (MIC) value (0.13 mg gallic acid equivalent (GAE)/ml) was exerted by HE-4 against S. aureus. These results indicate that tara gallotannins have the potential to inhibit pathogenic bacteria with potential application in foods as antimicrobials and their AA can be enhanced by acid hydrolysis. © 2014 Elsevier Ltd. All rights reserved.


Douieb S.,Eng-Tips | Fradette L.,URPEI | Bertrand F.,URPEI | Haut B.,Roosevelt University
AIChE Journal | Year: 2015

CO2 hydrate formation experiments are performed in a 20L semi-batch stirred tank reactor using three different impellers (a down-pumping pitched blade turbine, a Maxblend™, and a Dispersimax™) at various rotational speeds to examine the impact of the flow conditions on the CO2 hydrate formation rate. An original mathematical model of the CO2 hydrate formation process that assigns a resistance to each of its constitutive steps is established. For each experimental condition, the formation rate is measured and the rate-limiting step is determined on the basis of the respective values of the resistances. The efficiencies of the three considered impellers are compared and, for each impeller, the influence of the rotational speed on the rate-limiting step is discussed. For instance, it is shown that a formation rate limitation due to heat transfer can occur at the relatively small scale used to perform our experiments. © 2015 American Institute of Chemical Engineers.


Herman C.,Eng-Tips | Vermylen V.,UCB Pharma | Norberg B.,University of Namur | Wouters J.,University of Namur | Leyssens T.,Catholic University of Louvain
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials | Year: 2013

In this contribution different solid-state forms of the racemic compound (RS)-2-(2-oxo-pyrrolidin-1yl)-butyramide are studied from a structural and thermal point of view. Three different solid-state phases were identified, including two polymorphs and one hydrate phase. Comparison is made with the structure of the (S)-enantiomer, for which only one solid-state phase is known. The basic structural motif found in both polymorphs of the racemic compound is similar, but the basic motif observed for the hydrate differs. These synthons could in principle be used in future polymorph prediction studies to screen for possible alternative forms of the enantiopure compound. Based on the structure of the hydrate, further efforts should therefore be made in order to identify a hydrate structure of the enantiopure compound. Studying the different phases of a racemic compound can therefore help to guide polymorphic screening of an enantiopure compound. © 2013 International Union of Crystallography.


Talbot P.,Eng-Tips | Martinelli L.,Eng-Tips | Talvy S.,Eng-Tips | Chauveheid E.,Vivaqua | Haut B.,Eng-Tips
Water Research | Year: 2012

In this work, the ozone inactivation of resistant microorganisms is studied and a method to assess the efficiency of a drinking water plant to inactivate resistant microorganisms using ozone is proposed. This method aims at computing the fraction of resistant microorganisms that are not inactivated at the exit of an ozonation step by evaluating the duration of the lag phase of the ozone inactivation of these microorganisms and the contact time distribution of these microorganisms with the ozone in the step. To evaluate the duration of the lag phase of the ozone inactivation of resistant pathogenic microorganisms, an experimental procedure is proposed and applied to Bacillus subtilis spores. The procedure aims at characterizing the ozone inactivation kinetics of B. subtilis spores for different temperature and ozone concentration conditions. From experimental data, a model of the ozone inactivation of B. subtilis spores is built. One of the parameters of this model is called the lag time and it measures the duration of the lag phase of the ozone inactivation of B. subtilis spores. This lag time is identified for different temperature and ozone concentration conditions in order to establish a correlation between this lag time and the temperature and ozone concentration conditions. To evaluate the contact time distribution between microorganisms and the ozone in a disinfection step of a drinking water plant, a computational fluid dynamics tool is used. The proposed method is applied to the ozonation channel of an existing drinking water plant located in Belgium and operated by Vivaqua. Results show that lag times and contact times are both in the same order of magnitude of a few minutes. For a large range of temperatures and ozone concentrations in the Tailfer ozonation channel and for the highest hydraulic flow rate applied, a significant fraction of resistant microorganisms similar to B. subtilis spores is not inactivated. © 2012 Elsevier Ltd.


Talvy S.,Eng-Tips | Debaste F.,Eng-Tips | Martinelli L.,Eng-Tips | Chauveheid E.,Vivaqua | Haut B.,Eng-Tips
Chemical Engineering Science | Year: 2011

Foreseen standards regarding microorganism content for drinking water require assessment of the capability of existing plants to reach the upcoming requirements. This paper presents the development of a tool to assess this capability in a commonly encountered key step of water disinfection: ozonation. In this paper, this tool is applied to the test case of an ozonation channel of the Belgian drinking water producer Vivaqua. This tool is based on a mathematical model of the momentum and mass transport phenomena in an ozonation channel. The gas-liquid flow is coupled to ozone mass transfer and kinetics describing the ozone and microorganisms concentrations decay. The degradation of Bacillus subtilis spores, as a representative of resistant microorganisms, is implemented in the model. The model takes explicitly into account the bubble size variation and its impact on mass transfer. Bubbles sizes and kinetics parameters are estimated based on dedicated experiments. The model is partially validated by comparing simulations results, obtained using computational fluid dynamics, to experimental residence time distributions, residual ozone concentration and Bacillus subtilis spores degradation efficiency measurements obtained on the studied ozonation channel. It is shown that, at the industrial scale, bubble diameter variation has a significant impact on ozone concentration in the liquid at the reactor exit. Using the tool, it is also shown that, the ozonation channel of Vivaqua can be used to achieve degradation of resistant microorganisms but only with its maximal flow rate and concentration of ozone injection. Moreover, at low operating temperature, some microorganisms that present latency towards reaction with dissolved ozone might hardly be destroyed. © 2011 Elsevier Ltd.


Chambi F.,Agrarian National University | Chambi F.,Eng-Tips | Chirinos R.,Agrarian National University | Pedreschi R.,Wageningen UR Food and Biobased Research | And 3 more authors.
Industrial Crops and Products | Year: 2013

The antioxidant potential of tara pod extracts rich in gallotannins submitted to chemical hydrolysis was evaluated. The increase in the release of gallic acid from the tara pod extracts during the hydrolysis process reached a maximum ratio of free gallic acid/total phenolics of 94.1% at 20. h, at this point, 100% hydrolysis degree (HD) was obtained. After 4. h of hydrolysis (38.8% of HD) the highest antioxidant capacity was obtained reaching values of 25.9, 23.8 and 8.8. μmol trolox equivalent/mg gallic acid equivalent measured by ABTS, FRAP and ORAC methods. Lipophilicity diminished from 0.8 to 0.3 (log. P value). In addition, the antioxidant efficacy of 100. ppm total phenolics of hydrolyzates at 9. h (93.7% of HD) and 20. h showed to be significantly more efficient than a similar concentration of the synthetic antioxidant TBHQ to retard soybean oil oxidation. These results indicate that 4 and 9. h of chemical hydrolysis of tara pod extracts under the tested conditions are sufficient to obtain a product with good antioxidant properties to be used as an alternative source of antioxidants. © 2013 Elsevier B.V.


PubMed | Eng-Tips
Type: | Journal: Waste management (New York, N.Y.) | Year: 2017

This work is a preliminary study for the development of a co-pyrolysis process of plastic wastes excavated from a landfill and used lubrication oils, with the aim to produce an alternative liquid fuel for industrial use. First, thermogravimetric experiments were carried out with pure plastics (HDPE, LDPE, PP and PS) and oils (a motor oil and a mixture of used lubrication oils) in order to highlight the interactions occurring between a plastic and an oil during their co-pyrolysis. It appears that the main decomposition event of each component takes place at higher temperatures when the components are mixed than when they are alone, possibly because the two components stabilize each other during their co-pyrolysis. These interactions depend on the nature of the plastic and the oil. In addition, co-pyrolysis experiments were led in a lab-scale reactor using a mixture of excavated plastic wastes and used lubrication oils. On the one hand, the influence of some key operating parameters on the outcome of the process was analyzed. It was possible to produce an alternative fuel for industrial use whose viscosity is lower than 1Pas at 90C, from a plastic/oil mixture with an initial plastic mass fraction between 40% and 60%, by proceeding at a maximum temperature included in the range 350-400C. On the other hand, the amount of energy required to successfully co-pyrolyze, in lab conditions, 1kg of plastic/oil mixture with an initial plastic mass fraction of 60% was estimated at about 8MJ. That amount of energy is largely used for the thermal cracking of the molecules. It is also shown that, per kg of mixture introduced in the lab reactor, 29MJ can be recovered from the combustion of the liquid resulting from the co-pyrolysis. Hence, this co-pyrolysis process could be economically viable, provided heat losses are addressed carefully when designing an industrial reactor.


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