title: Absence of experimental evidence of a delta-shock in the system phenetole and 4-tert-butylphenol on Zorbax 300SB-C18.
abstract: We investigate the system consisting of phenetole (PNT) and 4-tert-butylphenol (TBP) in methanol-water (63:37 v:v) on a Zorbax 300SB-C18 column by characterising single component isotherms, by performing a large number of binary experiments of different types and by describing the experiments through simulations carried out using a novel, rather powerful competitive adsorption isotherm, that we call the generalized bi-Langmuir isotherm. This system is of great interest because it was previously reported to yield a new type of transition in nonlinear chromatography, the so-called delta-shock. Such transition had been discovered earlier through a theoretical analysis and confirmed by detailed simulations. The initial aim of this work was to reach a satisfactory agreement between delta-shock experiments and corresponding numerical simulations. In the course of this work however, a number of inconsistencies in the interpretation of the previous experimental results were highlighted and explained. This led to a new experimental campaign, which is reported here and has allowed to reach two important conclusions: (1) The binary system PNT-TBP mentioned above does not exhibit a delta-shock; the spike in the UV profile, which has previously been interpreted as an experimental evidence of the delta-shock, results from liquid-liquid phase separation within the chromatographic column. (2) The same system exhibits a rather peculiar behavior in breakthrough and displacement experiments, which could be well described using the generalized bi-Langmuir isotherm.
authors.affiliation: Institute of Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Jermann
authors.affiliation: Institute of Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland.
authors.forename: Franziska
authors.initials: F
authors.lastname: Ortner
authors.affiliation: Faculty of Engineering, Department of Chemical and Materials Engineering, University of Alberta, 9107-116 Street, Edmonton, AB T6G 2V4, Canada.
authors.forename: Arvind
authors.initials: A
authors.lastname: Rajendran
authors.affiliation: Institute of Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland. Electronic address: marco.mazzotti@ipe.mavt.ethz.ch.
authors.forename: Marco
authors.initials: M
authors.lastname: Mazzotti
mesh_terms: D000327:Adsorption; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002845:Chromatography / Q000295:instrumentation / Q000592:standards; D003198:Computer Simulation; D000432:Methanol / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D010647:Phenyl Ethers / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D010636:Phenols; D010647:Phenyl Ethers; D014867:Water; C006862:butylphen; C079413:phenetole; D000432:Methanol
keywords: Delta-shock; Non-linear chromatography