Laurence Muhr

Application of equilibrium theory to ternary moving bed configurations (four+four, five+four, eight and nine zones) I. Linear case.

In this article, different ternary moving bed configurations are studied by determining the working flow-rates of the equivalent true moving bed at the low solvent consumption point using equilibrium theory. This method has been applied for linear adsorption isotherms. The simulated moving bed flow-rates can then be calculated and a final comparison between the performances of each process is given based upon two different objective functions.

Investigation of transport phenomena in a hybrid ion exchange-electrodialysis system for the removal of copper ions

Hybrid ion exchange electrodialysis processes allow the removal of metal ions from dilute waste liquids and the recovery of more concentrated solutions. The work reported here was aimed at investigating the two steps in the treatment process, namely, adsorption of metal ions onto the packed bed of resin and electromigration (i.e., the transport of these ions in the complex system under the applied electrical field). The case of copper sulfate was investigated. Dowex™ resins with a cross-linking degree of 2 and 8% were used. The flux of copper through the resin bed and the current efficiency for ion transfer to the cathode compartment were determined as a function of potential gradient and copper ionic fraction in the bed. Apparent diffusion coefficients of Cu2+ in the overall system were deduced from the experimental data.

Application of the equilibrium theory to ternary moving bed configurations (4+4, 5+4, 8 and 9 zones): II. Langmuir case

In this article, the overall methodology used to determine the working flow-rates of a true moving bed (TMB) processing langmuirian isotherms compounds is explained. Then it is applied to different ternary configurations (4+4, 5+4, 8 or 9 zones TMB) in order to characterize their performances. Finally the results obtained on all the configurations are compared on a given example. This comparison allows the choice of the more suitable configuration to be used for a given set of compounds.

Bipolar membrane electrodialysis and ion exchange hybridizing for dilute organic acid solutions treatment

In this work, treatment of very dilute effluents of organic acids by means of an electro-membrane hybrid process is studied. Dilute organic acids effluents are generated by numerous processes. Converting such effluents into pure more concentrated fluxes is a key step in the valorization process. An experimental study has been performed to recover acetic acid by bipolar membrane electrodialysis (BMED). The experiments performed when coupling BMED and ion exchange have clearly demonstrated that hybridization reduces energy consumption. This improvement is due to the decrease of the electrical resistance of the diluted compartment thanks to the ionic conductivity provided by the resins. The effect of back diffusion on the current efficiency was also studied. In the case of acetic acid effluent treatment, investigation of the influence of the resin initial form showed that hydroxyl and acetate initial forms result in very close performances. It is therefore useless regenerating the resin bed.

ESIEX-Electrical Swing Ion Exchange a Process Coupling Ion Exchange, Carbonic Acid Elution, and Electrochemical Regeneration

A process which can be used for purification of a peptide is presented. This process is called ESIEX: Electrical Swing Ion Exchange. The principle of this process is based on a three steps cyclic mode, which avoids using pH buffers or generating wastes. The experimental set-up consists of an electrodialysis apparatus in which the cells are filled with anion exchange resins. Carbon dioxide dissolved in water is used as “green eluent.” Peptide is obtained pure. Assuming that equilibria in solution play a major role on the global separation factor compared to affinities for the support, peptides which can be fixed in a step but also eluted in another step should satisfy with a criterion: . The peptide dissociation constant must be between the two dissociation constants of carbonic acid, that is, 6.35 and 10.35 (at 298 K).