The Chemical Engineering Journal and The Biochemical Engineering Journal 

About: The Chemical Engineering Journal and The Biochemical Engineering Journal is an academic journal. The journal publishes majorly in the area(s): Mass transfer & Catalysis. It has an ISSN identifier of 0923-0467. Over the lifetime, 401 publications have been published receiving 7528 citations.

The use of the dusty-gas model for the description of mass transport with chemical reaction in porous media

Abstract: In the present study, mass transport accompanied by chemical reactions in porous media is studied according to the Fick model and the dusty-gas model. For mass transport accompanied by a chemical reaction in catalyst structures showing a plane, line, or point of symmetry, the approximate analytical concept of an effectiveness factor, accounting for intraparticle diffusion, was also evaluated. For a variety of reaction schemes and kinetic rate equations, a comparison was made between the results of the numerical models (Fick and dusty-gas) and the effectiveness-factor concept. From the results it was concluded that pressure in porous catalyst with a plane, line, or point of symmetry did not affect the fluxes seriously, and, therefore, the pressure-driven flow can be omitted from the flux expression without significant loss of accuracy. Furthermore, both for single and multiple reactions, the Fick model is satisfactorily accurate to estimate the transport rate in all cases, and the results deviate only slightly from the dusty-gas model. It should be noted that this latter model requires substantially more computational time. For catalytic membranes, however, transport of inert components as well as large trans-membrane pressure differences may be present, which affect the transport of the reactants and products. The calculations showed that, in contrast to the above-mentioned structures, in this case the dusty-gas model has to be used to describe the transport.

Biosorption of heavy metals by Zoogloea ramigera: use of adsorption isotherms and a comparison of biosorption characteristics

Abstract: The biosorption of lead(II), copper(II), nickel(II), and iron(III) ions on Zoogloea ramigera, an activated sludge bacterium, was studied with respect to adsorption pH and temperature in order to determine the optimum conditions for heavy metal removal. Optimum initial pH for the biosorption of lead(II), nickel(II) and copper(II) ions by Z. ramigera was determined as 4.0–4.5 whereas higher biosorptive uptake of iron(III) ions by Z. ramigera was obtained at pH 2.0. Maximum biosorption rates of nickel(II) and copper(II) ions by Z. ramigera where obtained at 25°C, while the initial biosorption rates and the adsorptive capacity of the biomass for lead(II) and iron(III) ions increased with increasing temperatures in the range 25–45°C. The adsorption isotherms were developed for optimum conditions and it was seen that the adsorption equilibrium data fit both Freundlich and Langmuir isotherms within the metal ion concentrations studied (25–200 mg 1−1). The adsorption constants for lead(II) and iron(III) were higher than those for nickel(II) and copper(II) for both Langmuir and Freundlich models.

Recovery of grape seed oil by liquid and supercritical carbon dioxide extraction: a comparison with conventional solvent extraction

Abstract: In this work the extraction of grape seed oil by means of liquid and supercritical carbon dioxide as solvent is described. The operating conditions to determine the maximum extraction yield were studied. The efficiency of supercritical fluid extraction (SFE) was similar to that obtained by conventional liquid extraction, but the quality of the supercritically extracted oil was higher, equivalent to a degummed, liquid- extracted oil. It is considered that SFE is competitive with conventional liquid extraction, because the solvent distillation and oil refining stages can be omitted.

Turbulent micromixing in chemical reactors - a review *

Abstract: The idea of micromixing, its definition and measures are outlined. The concepts of mixing environments and mixing earliness are presented. The paper concentrates on the effects of turbulent mixing of incompressible fluids in single-phase systems on the course of chemical reactions. The processes of turbulent micromixing are discussed in detail: the fluid mechanical interpretation of turbulent micromixing (effect of fluid element deformation on the acceleration of molecular diffusion, engulfing of environment, inertial—convective disintegration of large eddies and local intermittency) is presented. It is concluded that stretching of material elements and vortices, accompanied by molecular diffusion results in the growth of the mixing zones. The groth of the zone mixed on the molecular scale is a characteristic feature of micromixing and should be included in micromixing modelling. The characteristic time constants for the consecutive stages of mixing are presented and compared with the characteristic time for chemical reaction — the numerical criteria are outlined. The two approaches, i.e. eulerian and lagrangian, are described; it is shown that each requires different methods of description and generates specific problems (closure problem, problem of environment). The applications of the micromixing theory to the most important fields of industrial practice, such as complex reactions, precipitations and polymerizations, are outlined.