Effect of impeller type on the mixing in torus reactors

Torus reactors are characterized by a homogeneous fluid circulation without dead zones. Torus reactors were used for applications in biotechnology, food processing, polymerization and liquid waste treatments. The relatively simple extrapolation of performances, due to the absence of dead volume, is one of the main advantages of this reactor, with low shear stresses and an effective radial mixing allowing efficient heat dissipation. This study is based on the mixing in order to analyse the fluid circulation, mainly in turbulent flow regime, and to characterize the torus reactor with the axial dispersion plug flow model. The objective of this study is to characterize the flow and the mixing in the torus reactors in batch and continuous modes. The mixing analysis was made according to the flow parameters and to the geometrical characteristics of the reactor and impeller. The mixing in the torus reactor can be characterized by the P´eclet number, PeD, defined with torus diameter. A representative model based on plug flow with axial dispersion and partial recirculation was propose

Biosorption Behavior of Basic Red 46 and Violet 3 by Dead Pleurotus mutilus from Single- and Multicomponent Systems

The performance of nonviable P. mutilus for removal of Crystal Violet (CV) and Basic Red 46 (BR46) was investigated in single and binary systems. Batch kinetic studies were carried out as a function of pH, temperature, biomass amount, and dye concentration to determine the decolorization efficiency of biosorbent. In single system, the biosorption capacities of P. M. reached 166 and 76.92 mg/g for CV and BR46, respectively. A comparison of kinetic models applied to the adsorption of basic dyes onto P. Mutilus was evaluated for the pseudo-second-order and intraparticle diffusion kinetics models. The experimental data fitted very well the pseudo-second-order kinetic model, whereas diffusion is not only the rate-controlling step. The thermodynamic study indicates that the adsorption of dyes is spontaneous and endothermic process. In binary system, the biosorption capacities of P. Mutilus for both dyes decreased significantly compared to that in single system. Competitive coefficients calculated on a concentration basis using Sheindorf-Rebhun-Sheintuch (SRS) equation were useful for describing the degree of competitive interaction in P. M

Application of shrinking core model to the adsorption of oxytetracycline onto peanut hull-derived activated carbon in a closed-loop fixed-bed reactor

International audienceIn the present paper, the ability of peanut hull-derived activated carbon AC(PH-800) to adsorb oxytetracycline (OTC) was investigated using batch adsorption with fixed-bed reactor. The factors influencing adsorption, such as contact time and sorbent concentration, were evaluated. Sorption kinetic and equilibrium data of OTC sorption onto AC(PH-800) were submitted to kinetics and equilibrium models in order to calculate the adsorption constant rate and the maximum capacity of the sorbent. The application of shrinking core model (SCM) for the removal of OTC was investigated with two assumptions finite and infinite volume solution. Oxytetracycline adsorption increased for increasing initial OTC concentrations, and equilibrium isotherms can be accurately described by the Freundlich equation. Experimental data were analyzed using the SCM and the analysis based on statistical and graphical method proved that the adsorption followed the product layer diffusion controlled equation of the model. The approach modeling considering a finite volume solution assumption was more successful than the modeling approach involving an infinite volume solution

calcined Cu/Al layered double hydroxides: synthesis, caracterization and dye removal properties in tubular reactor

International audienc