Dynamic optimization of a gas-liquid reactor

The final publication is available at Springer via http://dx.doi.org/10.1007/s10910-011-9941-1A dynamic gas-liquid transfer model without chemical reaction based on unsteady film theory is considered. In this case, the mathematical model presented for gas-liquid mass-transfer processes is based on mass balances of the transferred substance in both phases. The identificability property of this model is studied in order to confirm the possible identifiable parameters of the model from a given set of experimental data. For that, a different modeled of the system is given. A procedure for the identification is proposed. On the other hand, the aim of this work is to solve the quadratic optimal control problem, using an explicit representation of the model. The problem includes some results on controllability, observability and stability criteria and the relation between these properties and the parameters of the model. Using the optimal control problem we study the stability of the system and show how the choice of the weighting matrices can improve the behavior of the system but with an increase of the energy control cost. © 2011 Springer Science+Business Media, LLC.This work has been partially supported by PAID-05-10-003-295 and by MTM2010-18228.Cantó Colomina, B.; Cardona Navarrete, SC.; Coll, C.; Navarro-Laboulais, J.; Sánchez, E. (2012). Dynamic optimization of a gas-liquid reactor. Journal of Mathematical Chemistry. 50(2):381-393. https://doi.org/10.1007/s10910-011-9941-1S381393502Bayón L., Grau J.M., Ruiz M.M., Suárez P.M.: Initial guess of the solution of dynamic optimization of chemical processes. J. Math. Chem. Model. 48, 28–37 (2010)Ben-Zvi A., McLellan P.J., McAuley K.B.: Ind. Eng. Chem. Res. 42, 6607–6618 (2003)Cantó B., Coll C., Sánchez E.: Structural identifiability of a model of dialysis. Math. Comp. Model. 50, 733–737 (2009)Cantó B., Coll C., Sánchez E.: Identifiability of a class of discretized linear partial differential algebraic equations. Math. Probl. Eng. 2011, 1–12 (2011)Craciun G., Pantea C.: Identifiability of chemical reaction networks. J. Math. Chem. 44, 244–259 (2008)Dai L.: Descriptor Control Systems. Springer, New York (1989)Deckwer W.D.: Bubble Column Reactors. Wiley, Chichester (1992)Kantarci N., Borak F., Ulgen K.O.: Bubble column reactors. Proc. Biochem. 40(7), 2263–2283 (2005)Kawakernaak H., Sivan R.: Linear Optimal Control Systems. Wiley-Interscience, New York (1972)Kuo B.C.: Automatic Control Systems, 6th edn. Prentice-Hall, Englewood Cliffs (1991)Navarro-Laboulais J., Cardona S.C., Torregrosa J.I., Abad A., López F.: Practical identifiability analysis in dynamic gas-liquid reactors. Optimal experimental design for mass-transfer parameters determination. Comp. Chem. Eng. 32, 2382–2394 (2008)Navarro-Laboulais J., López F., Torregrosa J.I., Cardona S.C., Abad A.: Transient response, model structure and systematic errors in hybrid respirometers: structural identifiabilit analysis based on OUR and DO measurements. J. Math. Chem. 44(4), 969–990 (2007)Patel R., Munro N.: Multivariable Systen. Theory and Design. Pergamon Press, New York (1982)Sondergeld K.: A generalization of the Routh–Hurwitz stability criteria and a application to a problem in robust controller design. IEEE Trans. Automat. Contr. AC-28(10), 965–970 (1983

A Central Partition of Molecular Conformational Space.III. Combinatorial Determination of the Volume Spanned by a Molecular System

In the first work of this series [physics/0204035] it was shown that the conformational space of a molecule could be described to a fair degree of accuracy by means of a central hyperplane arrangement. The hyperplanes divide the espace into a hierarchical set of cells that can be encoded by the face lattice poset of the arrangement. The model however, lacked explicit rotational symmetry which made impossible to distinguish rotated structures in conformational space. This problem was solved in a second work [physics/0404052] by sorting the elementary 3D components of the molecular system into a set of morphological classes that can be properly oriented in a standard 3D reference frame. This also made possible to find a solution to the problem that is being adressed in the present work: for a molecular system immersed in a heat bath we want to enumerate the subset of cells in conformational space that are visited by the molecule in its thermal wandering. If each visited cell is a vertex on a graph with edges to the adjacent cells, here it is explained how such graph can be built

On identifiability for chemical systems from measurable variables

The final publication is available at Springer via http://dx.doi.org/10.1007/s10910-013-0149-4The dynamics of the composition of chemical species in reacting systems can be characterized by a set of autonomous differential equations derived from mass conservation principles and some elementary hypothesis related to chemical reactivity. These sets of ordinary differential equations are basically non-linear, their complexity grows as much increases the number of substances present in the reacting media an can be characterized by a set of phenomenological constants which contains all the relevant information about the physical system. The determination of these kinetic constants is critical for the design or control of chemical systems from a technological point of view but the non-linear nature of the equations implies that there are hidden correlations between the parameters which maybe can be revealed with a identifiability analysis.This work has been partially supported by MTM2010-18228.Cantó Colomina, B.; Coll, C.; Sánchez, E.; Cardona Navarrete, SC.; Navarro-Laboulais, J. (2014). On identifiability for chemical systems from measurable variables. Journal of Mathematical Chemistry. 52(4):1023-1035. https://doi.org/10.1007/s10910-013-0149-4S10231035524M.J. Almendral, A. Alonso, M.S. Fuentes, Development of new methodologies for on-line determination of the bromate. J. Environ. Monit. 11, 1381–1388 (2009)A. Ben-Zvi, P.J. McLellan, K.B. McAuley, Identifiability of linear time-invariant differential-algebraic systems. I. The generalized Markov parameter approach. Ind. Eng. Chem. Res. 42, 6607–6618 (2003)T.P. Bonacquisti, A drinking water utility’s perspective on bromide, bromate, and ozonation. Toxicology 221, 145–148 (2006)R. Butler, A. Godley, L. Lytton, E. Cartmell, Bromate environmental contamination: review of impact and possible treatment. Crit. Rev. Environ. Sci. Tech. 35, 193–217 (2005)R. Butler, L. Lytton, A.R. Godley, I.E. Tothill, E. Cartmell, Bromate analysis in groundwater and wastewater samples. J. Environ. Monit. 7, 999–1006 (2005)B. Cantó, S.C. Cardona, C. Coll, J. Navarro-Laboulais, E. Sánchez, Dynamic optimization of a gas-liquid reactor. J. Math. Chem. 50, 381–393 (2012)B. Cantó, C. Coll and E. Sánchez, Identifiability of a class of discretized linear partial differential algebraic equations, Math. Problems Eng. 2011, 1–12 (2011)A. Constantinides, N. Mostoufi, Numerical Methods for Chemical Engineers with MATLAB Applications, Alkis Constantinides and Navid Mostoufi, Upper Saddle River (Prentice Hall, New Jersey, 1999)P. Englezos, N. Kalogerakis, Applied Parameter Estimation for Chemical Engineers (Marcel Dekker, New York, 2001)U. von Gunten, Ozonation of drinking water. Part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine. Water Res. 37, 1469–1487 (2003)B. Legube, B. Parinet, K. Gelinet, F. Berne, J-Ph Croue, Modeling of bromate formation by ozonation of surface waters in drinking water treatment. Water Res. 38, 2185–2195 (2004)Q. Liu, L.M. Schurter, C.E. Muller, S. Aloisio, J.S. Francisco, D.W. Margerum, Kinetics and mechanisms of aqueous ozone reactions with bromide, sulfite, hydrogen sulfite, iodide, and nitrite ions. Inorg. Chem. 40, 4436–4442 (2001)J.B. Rawling, J.G. Ekerdt, Chemical Reactor Analysis and Design Fundamentals (Nob Hill Pub, Madison, 2002)W.E. Stewart, M. Caracotsios, Computer Aided Modelling of Reactive Systems (John Wiley and Sons, New York, 2008)P. Westerhoff, R. Song, G. Amy, R. Minear, Numerical kinetic models for bromide oxidation to bromine and bromate. Water Res. 32, 1687–1699 (1998)World Health Organization, Bromate in Drinking-water, Document WHO/SDE/WSH/05.08/78, http://www.who.int/water_sanitation_health/dwq/chemicals/en/ (accesed 26/07/12

Experiencias de aplicación de la simulación empleando software libre y gratuito en la enseñanza de las ingenierías de la rama industrial

[ES] En este trabajo se presentan las experiencias de utilización de software libre y gratuito llevadas a cabo por el Equipo de Innovación y Calidad Educativa ASEI (Aplicación de la Simulación en la Enseñanza de la Ingeniería) en asignaturas de las áreas de Ingeniería Química, Nuclear y Estadística que requieren la utilización de software de cálculo y herramientas de simulación. El software libre puede ser utilizado como una herramienta en metodologías docentes basadas en el uso de la simulación en el aula de teoría o bien como una forma de disminuir los costes en la enseñanza y aportar nuevos valores. Adecuadamente empleadas, las metodologías basadas en el uso de programas de simulación pueden estimular la capacidad de autoaprendizaje del alumno. En esta comunicación se muestran ejemplos del amplio abanico de aplicaciones de software que se pueden utilizar sin representar coste para la Universidad y posteriormente para la empresa.Santafé Moros, MA.; Gozálvez-Zafrilla, JM.; Navarro-Laboulais, J.; Cardona, SC.; Miró Herrero, R.; García-Díaz, JC. (2014). Experiencias de aplicación de la simulación empleando software libre y gratuito en la enseñanza de las ingenierías de la rama industrial. Editorial Universitat Politècnica de València. 324-342. http://hdl.handle.net/10251/167124S32434

Efficient and Specific Internal Cleavage of a Retroviral Palindromic DNA Sequence by Tetrameric HIV-1 Integrase

BACKGROUND: HIV-1 integrase (IN) catalyses the retroviral integration process, removing two nucleotides from each long terminal repeat and inserting the processed viral DNA into the target DNA. It is widely assumed that the strand transfer step has no sequence specificity. However, recently, it has been reported by several groups that integration sites display a preference for palindromic sequences, suggesting that a symmetry in the target DNA may stabilise the tetrameric organisation of IN in the synaptic complex. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the ability of several palindrome-containing sequences to organise tetrameric IN and investigated the ability of IN to catalyse DNA cleavage at internal positions. Only one palindromic sequence was successfully cleaved by IN. Interestingly, this symmetrical sequence corresponded to the 2-LTR junction of retroviral DNA circles-a palindrome similar but not identical to the consensus sequence found at integration sites. This reaction depended strictly on the cognate retroviral sequence of IN and required a full-length wild-type IN. Furthermore, the oligomeric state of IN responsible for this cleavage differed from that involved in the 3'-processing reaction. Palindromic cleavage strictly required the tetrameric form, whereas 3'-processing was efficiently catalysed by a dimer. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that the restriction-like cleavage of palindromic sequences may be a general physiological activity of retroviral INs and that IN tetramerisation is strongly favoured by DNA symmetry, either at the target site for the concerted integration or when the DNA contains the 2-LTR junction in the case of the palindromic internal cleavage

Ozonation Kinetics of Acid Red 27 Azo Dye: A novel methodology based on artificial neural networks for the determination of dynamic kinetic constants in bubble column reactors

A procedure for the determination of initial parameter values for quadratically convergent optimization methods is proposed using artificial neural networks coupled with a non-stationary gas-liquid reaction model. The evaluation of the regression and the mean squared error coefficients of the neural network during its training process allow the parameter sensitivity analysis of the gas-liquid model. This analysis examines how many and which parameters of the model will be available depending on the observable information of the mathematical model. Numerical simulations show the relevance of the initial values and the non-linearity of the objective function. The methodology has been applied to the study of the reaction of the azo-dye Acid Red 27 with ozone in acid media. The rate constant is in the order of (1.6 +-0.1) 10^3M^(-1) s ^(-1) under the experimental conditions.J. Ferre-Aracil acknowledges the support of the doctoral fellowship from the Universitat Politecnica de Valencia (UPV-PAID-FPI-2010-04).Ferre Aracil, J.; Cardona, SC.; Navarro-Laboulais, J. (2015). Ozonation Kinetics of Acid Red 27 Azo Dye: A novel methodology based on artificial neural networks for the determination of dynamic kinetic constants in bubble column reactors. Chemical Engineering Communications. 202(3):279-293. https://doi.org/10.1080/00986445.2013.841146S279293202

Kinetic study of ozone decay in homogeneous phosphate-buffered medium

The ozone decomposition reaction is analyzed in a homogeneous reactor through in-situ measurement of the ozone depletion. The experiments were carried out at pHs between 1 to 11 in H2PO4-/HPO42 buffers at constant ionic strength (0.1 M) and between 5 and 35 ºC. A kinetic model for ozone decomposition is proposed considering the existence of two chemical subsystems, one accounting for direct ozone decomposition leading to hydrogen peroxide and the second one accounting for the reaction between the hydrogen peroxide with the ozone to give different radical species. The model explains the apparent reaction order respect of the ozone for the entire pH interval. The decomposition kinetics at pH 4.5, 6.1, and 9.0 is analyzed at different ionic strength and the results suggest that the phosphate ions do not act as a hydroxyl radical scavenger in the ozone decomposition mechanism.J. Ferre-Aracil acknowledges the support of the doctoral fellowship from the Universitat Politecnica de Valencia (UPV-PAID-FPI-2010-04).Ferre Aracil, J.; Cardona, SC.; Navarro-Laboulais, J. (2015). Kinetic study of ozone decay in homogeneous phosphate-buffered medium. Ozone: Science and Engineering. 37(4):330-342. https://doi.org/10.1080/01919512.2014.998756S330342374Bezbarua, B. K., & Reckhow, D. A. (2004). Modification of the Standard Neutral Ozone Decomposition Model. Ozone: Science & Engineering, 26(4), 345-357. doi:10.1080/01919510490482179Bielski, B. H. J., Cabelli, D. E., Arudi, R. L., & Ross, A. B. (1985). Reactivity of HO2/O−2 Radicals in Aqueous Solution. Journal of Physical and Chemical Reference Data, 14(4), 1041-1100. doi:10.1063/1.555739Biń, A. K., Machniewski, P., Wołyniec, J., & Pieńczakowska, A. (2013). Modeling of Ozone Reaction with Benzaldehyde Incorporating Ozone Decomposition in Aqueous Solutions. Ozone: Science & Engineering, 35(6), 489-500. doi:10.1080/01919512.2013.821595Black, E. D., & Hayon, E. (1970). Pulse radiolysis of phosphate anions H2PO4-, HPO42-, PO43-, and P2O74- in aqueous solutions. The Journal of Physical Chemistry, 74(17), 3199-3203. doi:10.1021/j100711a007Buehler, R. E., Staehelin, J., & Hoigne, J. (1984). Ozone decomposition in water studied by pulse radiolysis. 1. Perhydroxyl (HO2)/hyperoxide (O2-) and HO3/O3- as intermediates. The Journal of Physical Chemistry, 88(12), 2560-2564. doi:10.1021/j150656a026Buxton, G. V., Greenstock, C. L., Helman, W. P., & Ross, A. B. (1988). Critical Review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (⋅OH/⋅O− in Aqueous Solution. Journal of Physical and Chemical Reference Data, 17(2), 513-886. doi:10.1063/1.555805Cantó, B., Cardona, S. C., Coll, C., Navarro-Laboulais, J., & Sánchez, E. (2011). Dynamic optimization of a gas-liquid reactor. Journal of Mathematical Chemistry, 50(2), 381-393. doi:10.1007/s10910-011-9941-1Cantó, B., Coll, C., Sánchez, E., Cardona, S. C., & Navarro-Laboulais, J. (2013). On identifiability for chemical systems from measurable variables. Journal of Mathematical Chemistry, 52(4), 1023-1035. doi:10.1007/s10910-013-0149-4Cardona, S. C., López, F., Abad, A., & Navarro-Laboulais, J. (2010). On bubble column reactor design for the determination of kinetic rate constants in gas-liquid systems. The Canadian Journal of Chemical Engineering, 88(4), 491-502. doi:10.1002/cjce.20327Ershov, B. G., & Gordeev, A. V. (2008). A model for radiolysis of water and aqueous solutions of H2, H2O2 and O2. Radiation Physics and Chemistry, 77(8), 928-935. doi:10.1016/j.radphyschem.2007.12.005Fábián, I. (2006). Reactive intermediates in aqueous ozone decomposition: A mechanistic approach. Pure and Applied Chemistry, 78(8), 1559-1570. doi:10.1351/pac200678081559Ferre-Aracil, J., Cardona, S. C., López, F., Abad, A., & Navarro-Laboulais, J. (2013). Unstationary Film Model for the Determination of Absolute Gas-Liquid Kinetic Rate Constants: Ozonation of Acid Red 27, Acid Orange 7, and Acid Blue 129. Ozone: Science & Engineering, 35(6), 423-437. doi:10.1080/01919512.2013.815104Ferre-Aracil, J., Cardona, S. C., & Navarro-Laboulais, J. (2014). Determination and Validation of Henry’s Constant for Ozone in Phosphate Buffers Using Different Analytical Methodologies. Ozone: Science & Engineering, 37(2), 106-118. doi:10.1080/01919512.2014.927323Gardoni, D., Vailati, A., & Canziani, R. (2012). Decay of Ozone in Water: A Review. Ozone: Science & Engineering, 34(4), 233-242. doi:10.1080/01919512.2012.686354Grasso, D., & Weber, W. J. (1989). Mathematical Interpretation of Aqueous‐phase Ozone Decomposition Rates. Journal of Environmental Engineering, 115(3), 541-559. doi:10.1061/(asce)0733-9372(1989)115:3(541)Gurol, M. D., & Singer, P. C. (1982). Kinetics of ozone decomposition: a dynamic approach. Environmental Science & Technology, 16(7), 377-383. doi:10.1021/es00101a003Kosaka, K., Yamada, H., Matsui, S., Echigo, S., & Shishida, K. (1998). Comparison among the Methods for Hydrogen Peroxide Measurements To Evaluate Advanced Oxidation Processes:  Application of a Spectrophotometric Method Using Copper(II) Ion and 2,9-Dimethyl-1,10-phenanthroline. Environmental Science & Technology, 32(23), 3821-3824. doi:10.1021/es9800784Maruthamuthu, P., & Neta, P. (1978). Phosphate radicals. Spectra, acid-base equilibriums, and reactions with inorganic compounds. The Journal of Physical Chemistry, 82(6), 710-713. doi:10.1021/j100495a019Merényi, G., Lind, J., Naumov, S., & Sonntag, C. von. (2010). Reaction of Ozone with Hydrogen Peroxide (Peroxone Process): A Revision of Current Mechanistic Concepts Based on Thermokinetic and Quantum-Chemical Considerations. Environmental Science & Technology, 44(9), 3505-3507. doi:10.1021/es100277dMerényi, G., Lind, J., Naumov, S., & von Sonntag, C. (2010). The Reaction of Ozone with the Hydroxide Ion: Mechanistic Considerations Based on Thermokinetic and Quantum Chemical Calculations and the Role of HO4−in Superoxide Dismutation. Chemistry - A European Journal, 16(4), 1372-1377. doi:10.1002/chem.200802539Minchew, E. P., Gould, J. P., & Saunders, F. M. (1987). Multistage Decomposition Kinetics of Ozone In Dilute Aqueous Solutions. Ozone: Science & Engineering, 9(2), 165-177. doi:10.1080/01919518708552401Mizuno, T., Tsuno, H., & Yamada, H. (2007). Development of Ozone Self-Decomposition Model for Engineering Design. Ozone: Science & Engineering, 29(1), 55-63. doi:10.1080/01919510601115849Morozov, P. A., & Ershov, B. G. (2010). The influence of phosphates on the decomposition of ozone in water: Chain process inhibition. Russian Journal of Physical Chemistry A, 84(7), 1136-1140. doi:10.1134/s0036024410070101Schick, R., Strasser, I., & Stabel, H.-H. (1997). Fluorometric determination of low concentrations of H2O2 in water: Comparison with two other methods and application to environmental samples and drinking-water treatment. Water Research, 31(6), 1371-1378. doi:10.1016/s0043-1354(96)00410-1Sehested, K., Corfitzen, H., Holcman, J., & Hart, E. J. (1992). Decomposition of ozone in aqueous acetic acid solutions (pH 0-4). The Journal of Physical Chemistry, 96(2), 1005-1009. doi:10.1021/j100181a084Sehested, K., Holcman, J., Bjergbakke, E., & Hart, E. J. (1982). Ultraviolet spectrum and decay of the ozonide ion radical, O3-, in strong alkaline solution. The Journal of Physical Chemistry, 86(11), 2066-2069. doi:10.1021/j100208a031Sehested, K., Holcman, J., Bjergbakke, E., & Hart, E. J. (1984). Formation of ozone in the reaction of hydroxyl with O3- and the decay of the ozonide ion radical at pH 10-13. The Journal of Physical Chemistry, 88(2), 269-273. doi:10.1021/j150646a021Sein, M. M., Golloch, A., Schmidt, T. C., & von Sonntag, C. (2007). No Marked Kinetic Isotope Effect in the Peroxone (H2O2/D2O2+O3) Reaction: Mechanistic Consequences. ChemPhysChem, 8(14), 2065-2067. doi:10.1002/cphc.200700493Sotelo, J. L., Beltran, F. J., Benitez, F. J., & Beltran-Heredia, J. (1987). Ozone decomposition in water: kinetic study. Industrial & Engineering Chemistry Research, 26(1), 39-43. doi:10.1021/ie00061a008Staehelin, J., & Hoigne, J. (1982). Decomposition of ozone in water: rate of initiation by hydroxide ions and hydrogen peroxide. Environmental Science & Technology, 16(10), 676-681. doi:10.1021/es00104a009Weiss, J. (1935). The catalytic decomposition of hydrogen peroxide on different metals. Transactions of the Faraday Society, 31, 1547. doi:10.1039/tf935310154