A thermodynamic and kinetic study of an unusual adsorption behavior-Methyl Mandelate on commercially available Tris-(3,5- dimethylphenyl)carbamoyl Cellulose Chiral Stationary Phase

• The adsorption equilibria of racemic methyl mandelate on a tris-(3,5- dimethylphenyl)carbamoyl cellulose chiral stationary phase (CSP) was investigated. The following were observed, the less retained enantiomer shows “Langmuirian” (type I) adsorption behavior, while the adsorption isotherm of the more retained compound contained an inflection point at low concentration. To analyze these differences, adsorption isotherms were determined and further analyzed using Scatchard plots and adsorption energy distribution (AED) calculations. The less retained enantiomer was best described by heterogeneous unimodal adsorption model (Tóth) while the second enantiomer was best described with a heterogeneous adsorption model with adsorbate-adsorbate interactions (bi-Moreau). The adsorption behavior of both enantiomers was also studied at several different temperatures and it was found to be exothermic; in addition, the non-idealadsorbate-adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process could identify a single kinetic site for each enantiomer. The average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature. This is an industrial – academic cooperation in the Fundamental Separation Science Group www.separationscience.se

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NATURVETENSKAP  -- Kemi -- Analytisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Analytical Chemistry (hsv//eng)

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