Separ at ion IDPur if icat ion Technology ELSEVIER Separation and Purification Technology 13 (1998) 25-35 Adsorption of phenylalanine onto polymeric resins: equilibrium, kinetics and operation of a parametric pumping unit Sergi Diez a, Anabela Leitgo b, Licinio Ferreira ‘, Alirio Rodrigues d** a zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Department of Civil and Environmental Engineering, M assachusetts Institute of Technology, Cambridge, MA 02139, USA b Universidade Agostinho Neto, Departamento de Engenharia Quimica, Luanda, Angola ’ Universidade de Coimbra, Departamento de Engenharia Quimica, 3000 Coimbra, Portugal a Laboratory of Separation and Reaction Engineering, School of Engineering, University of Porto, 4099 Porto Codex, Portugal Accepted 4 September 1997 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 x 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 x 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. 0 1998 Elsevier Science B.V. Keywords: Adsorption; parametric pumping; phenylalanine; purification 1. Introduction Adsorptive separations are widely used in chemi- cal engineering applications for the purification of fluid streams, recovery of solutes and bulk separa- tions. The importance of adsorption processes has been recently stressed in various reviews [l-3]. Conventional fixed-bed processes involve satura- tion, adsorption or loading step followed by desorption, elution or regeneration steps and eventually washing steps. The performance of * Corresponding author. 1383-5866/98/$19.00 0 1998 Elsevier Science B.V. All rights reserved. PZZ S1383-5866(97)00053-l fixed-bed adsorption is governed in the first instance by the nature of the adsorption equilib- rium isotherm. The simplest equilibrium model tells us that the breakthrough curve will be a shock (compressive wave) in the case of favorable iso- therms (Langmuir type) and a dispersive wave in the case of unfavorable isotherms. For linear isotherms, equilibrium theory predicts a contact discontinuity for a step input on the feed concen- tration. The overall economy of the process must therefore consider the complete cycle. A favorable isotherm is convenient as far as adsorption is concerned, but regeneration is more difficult.