Grigore Bozga
Politehnica University of Bucharest
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Publication
Featured researches published by Grigore Bozga.
Langmuir | 2017
Nicolas Sereni; Alin Enache; Guillaume Sudre; Alexandra Montembault; Cyrille Rochas; Philippe Durand; Marie-Hélène Perrard; Grigore Bozga; Jean-Pierre Puaux; Thierry Delair; Laurent David
We studied the microstructure of physical chitosan hydrogels formed by the neutralization of chitosan aqueous solutions highlighting the structural gradients within thick gels (up to a thickness of 16 mm). We explored a high polymer concentrations range (Cp ≥ 1.0% w/w) with different molar masses of chitosan and different concentrations of the coagulation agent. The effect of these processing parameters on the morphology was evaluated mainly through small-angle light scattering (SALS) measurements and confocal laser scanning microscopy (CLSM) observations. As a result, we reported that the microstructure is continuously evolving from the surface to the bulk, with mainly two structural transitions zones separating three types of hydrogels. The first zone (zone I) is located close to the surface of the hydrogel and constitutes a hard (entangled) layer formed under fast neutralization conditions. It is followed by a second zone (zone II) with a larger thickness (∼3-4 mm), where in some cases large pores or capillaries (diameter ∼10 μm) oriented parallel to the direction of the gel front are present. Deeper in the hydrogel (zone III), a finer oriented microstructure, with characteristic sizes lower than 2-3 μm, gradually replace the capillary morphology. However, this last bulk morphology cannot be regarded as structurally uniform because the size of small micrometer-range-oriented pores continuously increases as the distance to the surface of the hydrogel increases. These results could be rationalized through the effect of coagulation kinetics impacting the morphology obtained during neutralization.
Computer-aided chemical engineering | 2003
Grigore Bozga; Gheorghe Bumbac; Valentin Plesu; Ilie Muja; Corneliu Dan Popescu
The work presents a simulation study of a reactive distillation (RD) unit for tert-amyl-methyl-ether synthesis using HYSYSTM simulation environment. In order to simulate the RD column this was represented as an ensemble of three components corresponding to the software chemical operation modules avialable in HYSYS. The calculated iso-amylenes conversion was compared with measured values on a pilot plant RD unit.
Chemical Engineering & Technology | 2001
Ion Iliuta; Grigore Bozga; Mihai Lupascu
Benzene alkylation with propylene over a Ca modified HY zeolite to obtain cumene has been studied. Time on stream behavior of the catalyst was quite steady without any sign of deactivation and the results were reproducible. The external mass transfer does not influence the cumene reaction. The pore diffusion has a substantial influence on the cumene reaction only in the final region of the reactor, where the olefin concentration is very low. A simple power law kinetic model fits the experimental data significantly better than other models. A general time and space dependent model was developed to analyze the performance of a two-phase downflow fixed bed reactor used for alkylation of benzene with zeolite catalyst. The model could be instructive in exploratory simulations evaluating the conditions for benzene alkylation in liquid phase.
Computer-aided chemical engineering | 2012
Elena Vlad; Costin Sorin Bildea; Grigore Bozga
Abstract A nonlinear approach to design of process systems is presented and applied to glycerol etherification plant. Depending on the operational parameters, the system shows either two or no steady states. Moreover, the flow rates are constrained by the available equipment. The critical manifolds separating the stability/instability and feasibility/unfeasibility domains should not be crossed when the system is disturbed or the design parameters are uncertain. Nonlinear analysis and constructive (synthesis-oriented) methods, ensuring the robustness of the design, are presented. The dynamic performance is assessed using rigorous process simulation in Aspen Dynamics.
Computer-aided chemical engineering | 2011
Elena Vlad; Costin Sorin Bildea; Elena Zaharia; Grigore Bozga
Abstract The feasibility of an industrial-scale, acid-catalyzed process for etherification of glycerol with i-butene is analyzed. A simplified mass balance of the process is derived using a kinetic model for the reactor and black-box model for the separation section. Sensitivity analysis of the steady state model shows that the system exhibits both state multiplicity and regions where no solution exists. The nominal operating point is chosen to avoid high sensitivity to disturbances and to guarantee feasibility when operation and design parameters are uncertain. The stability and robustness in operation are checked by rigorous dynamic simulation.
Computer-aided chemical engineering | 2009
Costin Sorin Bildea; Cristian C. Brunchi; Grigore Bozga
The feasibility of glycerol etherification is investigated, considering olefins, alcohols and ethers as co-reactants. Details are presented for the reaction between glycerol and iso-butene. Simultaneous phase and chemical equilibrium calculations show that large glycerol conversion can be obtained at a good selectivity towards the desired di-ether. The behaviour of the reactor-separation-recycle flowsheet is analyzed, demonstrating that the recycle of the mono-ether has a beneficial effect. About 1 m3 of reactor volume is necessary for producing 1 kmol/h of di-ether, while the recycle rates of glycerol and mono-ethers are kept at small values.
Macromolecular Symposia | 2007
Jean-Pierre Puaux; Ionut Banu; Iosif Nagy; Grigore Bozga
Food and Bioproducts Processing | 2009
Jordi Bonet; José Sánchez Costa; Romain Sire; Jean-Michel Reneaume; Alexandra Elena Pleşu; Valentin Plesu; Grigore Bozga
Energy | 2008
Alexandra Elena Pleşu; Jordi Bonet; Valentin Plesu; Grigore Bozga; Maria Isabel Galan
Applied Catalysis B-environmental | 2008
Magdalena Bosomoiu; Grigore Bozga; Daniela Berger; Cristian Matei