Licínio M. Ferreira

Adsorption of phenylalanine onto polymeric resins: equilibrium, kinetics and operation of a parametric pumping unit

Abstract Adsorption of d, l -Phenylalanine onto polymeric adsorbents (Amberlite XAD-4 and XAD-16; Sephabeads SP206 and SP207) was studied. Adsorption equilibrium isotherms were measured by batch equilibration at 15 and 40°C, showing the possibility of using a parametric pumping technique for aminoacid purification/recovery. Dynamic studies in a laboratory adsorption column Amicon Column (22 × 500 mm) were carried out to further screen adsorbents and obtain mass transfer parameters to be used in the modeling, simulation and operation of the pilot parametric pumping unit. The pilot plant includes a Amicon Columnn (90 × 1000 mm) and is completely automated. A package for the simulation of this cyclic operation was developed. Simulated and experimental results using Sephabeads SP206 (Mitsubishi Kasei Corporation, Japan) are in good agreement.

A package for thermal parametric pumping adsorptive processes

Abstract Thermal parametric pumping is a cyclic adsorptive process based on cyclic changes in the bed temperature simultaneously with flow reversal. Simplified models are adequate to describe these cyclic processes with long cycle times. Two simplified models are used here: Model I is an equilibrium model plus axial dispersion and Model II accounts for intraparticle mass transfer with LDF approximation. Simulations used parameter values obtained for the system phenol/water/ adsorbent resin Duolite ES861. Model validation is carried out by performing experiments in a pilot plant with the system phenylalanine/water/polymeric adsorbent SP206 and using published experimental data for the system phenol/water/adsorbent resin Duolite ES861. A user-friendly package ‘Visual Pumping’ (VP) is developed in Visual Basic for the simulation of thermal parametric pumping processes with educational and training purposes.

An analytical and experimental study of heat transfer in fixed bed

Abstract Heat transfer in a fixed-bed packed with polymeric adsorbent particles, percolated by a liquid phase flowing upward at 60 °C or downward at 20 °C, is experimentally studied in a column 9 cm in diameter and 1 m in length. The transient temperature profiles were measured axially and radially in the column. Sensitivity function calculations enabled to prove that the thermal parameters could be estimated from the experimental data and also to obtain information about the optimum location of the sensors. Experimental transient temperature responses were compared to those predicted by one-dimensional (1-D) and two-dimensional ( 2-D) pseudo-homogeneous (PH) models. By fitting the 2-D model solution to the experimental responses, values for the thermal parameter, effective radial and axial conductivities and the wall heat transfer coefficient were found.

Adsorptive separation by thermal parametric pumping part II: Experimental study of the purification of aqueous phenolic solutions at pilot scale

In this work scale-up concerns in adsorptive parametric pumping operation in recuperative mode are studied. An experimental study of the purification of wastewater containing 100 ppm of phenol using a polymeric adsorbent (Duolite ES861-Rohm and Haas, France) is reported. A completely automated pilot plant (column and ancillary equipment, product receivers, sampling, collector and analytical devices) is described. The plant is computer controlled enabling automatic data acquisition for temperature, pressure and flowrate.Parameters related with adsorption equilibrium, mass transfer and heat transfer resistances were determined in order to obtain basic information to simulate the process behavior.Continuous and semicontinuous top feed parametric pumping experiments were carried out in a bed with 0.09 m diameter and 1 m long which represents a scale-up by a factor of 60 relative to previous works. Optimal operating conditions yielding the maximum productivity of the bottom product (phenol concentration <1 ppm), were achieved experimentally with the following conditions: average cycle time =4 h, ratioφB/φT=2 (φB=0.27), reservoir volumeQ(π/ω)=32.5l, average flowrate=0.24l/min. Based on these conditions, after 12 cycles of operation, 105l of treated water is obtained. Those optimal operating conditions were suggested by simulation studies presented in Part I (Ferreira and Rodrigues, 1995) of this work.Good agreement was obtained between experimental and simulated results using the complete model developed in Part I (Ferreira and Rodrigues, 1995).

Adsorptive separation by thermal parametric pumping part I: Modeling and simulation

A detailed model for the recuperative parametric pumping is presented. The model includes intraparticle mass transfer resistance, axial diffusion and non-linear equilibrium represented by Langmuir equation. The sensitivity studies shows that process performance strongly increases when cycle time increases and φB/φT ratio and particle size decreases. It also shows that bottom and top dead volumes do not influence much the process performance. Evolution of the histories of concentrations and temperatures, the bed performance from cycle to cycle and the bed dynamics at the cyclic steady state have been discussed.The model revealed itself as useful to simulate the behavior of the recuperative parametric pumping process and was applied to predict optimal experimental results for the system phenol-water/Duolite ES-861 (Part II).

Binary Adsorption of Phenol and m-Cresol Mixtures onto a Polymeric Adsorbent

Adsorption processes are gaining interest as methods of purifying industrial effluents. Most industries discharge effluents containing several components. The adsorption of phenol and m-cresol mixtures from aqueous solutions onto a macroporous polymeric adsorbent, Duolite ES-861, was investigated experimentally in a fixed-bed adsorber for different flowrates, feed concentrations and bed initial conditions (clean or pre-saturated).The experimental results are presented in this work, where the major objective is placed on the modelling of these fixed bed adsorption experiments using an extended Langmuir isotherm equation for two components, based on single component equilibrium data obtained for phenol and m-cresol.The model presented in this paper takes into account axial dispersion of the liquid phase, film diffusion and intraparticle mass transfer and successfully simulates the adsorption behaviour of the phenol and m-cresol mixtures.