Lewis acid‐base properties of cellulose acetate butyrate by inverse gas chromatography |
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Authors: | P Reddi Rani S Ramanaiah K S Reddy |
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Institution: | Department of Chemistry, Sri Venkateswara University, Tirupati‐517 502, India. |
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Abstract: | The dispersive component of the surface‐free energy, , of cellulose acetate butyrate (CAB) has been determined using the net retention volume, VN, of n‐alkanes (C5? C8) probes in the temperature range 323.15–393.15 K. The values decrease nonlinearly with increase in temperature, and the temperature coefficients of are ? 0.32 (mJ/m2K) and ? 0.10 (mJ/m2K) in the range 323.15–353.15 K and 353.15–393.15 K, respectively. This variation in has been attributed to the structural changes that take place on the surface of CAB at ~353.15 K. The specific components of the enthalpy of adsorption, , and entropy of adsorption, , calculated using VN of polar solutes are negative. The values are used to evaluate Lewis acidity constant, Ka, and Lewis basicity constant, Kb, for the CAB surface. The Ka and Kb values are found to be 0.126 and 1.109, respectively, which suggest that the surface is predominantly basic. The Ka and Kb results indicate for the necessary surface modifications of CAB which act as biodegradable adsorbent material. Copyright © 2010 John Wiley & Sons, Ltd. |
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Keywords: | Lewis acid‐base parameters cellulose acetate butyrate inverse gas chromatography |
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