title: Adsorption Kinetics at Silica Gel/Ionic Liquid Solution Interface.
abstract: A series of imidazolium and pyridinium ionic liquids with different anions (Cl(-), Br(-), BF₄(-), PF₆(-)) has been evaluated for their adsorption activity on silica gel. Quantification of the ionic liquids has been performed by the use of RP-HPLC with organic-aqueous eluents containing an acidic buffer and a chaotropic salt. Pseudo-second order kinetic models were applied to the experimental data in order to investigate the kinetics of the adsorption process. The experimental data showed good fitting with this model, confirmed by considerably high correlation coefficients. The adsorption kinetic parameters were determined and analyzed. The relative error between the calculated and experimental amount of ionic liquid adsorbed at equilibrium was within 7%. The effect of various factors such as initial ionic liquid concentration, temperature, kind of solvent, kind of ionic liquid anion and cation on adsorption efficiency were all examined in a lab-scale study. Consequently, silica gel showed better adsorptive characteristics for imidazolium-based ionic liquids with chaotropic anions from aqueous solutions in comparison to pyridinium ionic liquids. The adsorption was found to decrease with the addition of organic solvents (methanol, acetonitrile) but it was not sensitive to the change of temperature in the range of 5-40 °C.
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, 4a Chodźki St., Lublin PL-20093, Poland. j.flieger@umlub.pl.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Flieger
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, 4a Chodźki St., Lublin PL-20093, Poland. m.tatarczak@op.pl.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Tatarczak-Michalewska
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, 4a Chodźki St., Lublin PL-20093, Poland. a.groszek@onet.eu.
authors.forename: Anna
authors.initials: A
authors.lastname: Groszek
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, 4a Chodźki St., Lublin PL-20093, Poland. bayrena@tlen.pl.
authors.forename: Eliza
authors.initials: E
authors.lastname: Blicharska
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, 4a Chodźki St., Lublin PL-20093, Poland. ryszard.kocjan@umlub.pl.
authors.forename: Ryszard
authors.initials: R
authors.lastname: Kocjan
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000327:Adsorption; D006219:Halogens / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D007700:Kinetics; D000432:Methanol / Q000737:chemistry; D058428:Silica Gel / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods; D013816:Thermodynamics
chemical_list: C412621:1-butyl-3-methylimidazolium hexafluorophosphate; C419324:1-butyl-3-methylimidazolium tetrafluoroborate; D000097:Acetonitriles; D006219:Halogens; D007093:Imidazoles; D052578:Ionic Liquids; D058428:Silica Gel; D000432:Methanol; C032159:acetonitrile
keywords: ionic liquids; pseudo-second-order equation; silica gel; sorption kinetics