MEASUREMENT OF TEMPERATURE-DEPENDENCE OF CYCLODEXTRIN BINDING CONSTANT USING ULTRAFILTRATION

The temperature dependence of the binding constant K-B for cyclodextri n (CD) and nitrophenol (NP) system is investigated using a previously proposed method. The method is based on the selective inclusion proper ty of cyclodextrin (CD) and the selective permeability of the ultrafil tration membrane (UF/m). K-B decreases with increasing temperature. Me anwhile, the activation energy of binding (Delta E-T) is calculated fr om the Arrhenius plot and it is a negative value. The absolute values of Delta E-T become large in the order of o-, m-, and p-NPs, These val ues approximately agree with those of other investigators who employed other methods. Furthermore, the forcible binding energy Delta E-F is calculated from the pressure (P-d), where the rise ratio of rejection (eta) begins deviating from the constant value which is measured at lo wer pressure. Delta E-F agrees with Delta E-T. The ratio of Delta E-T to Delta E-F is nearly constant at 7, and independent of pH and the re action system.