Adsorption characteristics of bisphenol-A in aqueous solutions onto hydrophobic zeolite

The adsorption behavior of bisphenol-A, which is a hydrophobic organic compound and also listed as one of endocrine disrupting chemicals, from aqueous solution onto hydrophobic zeolite at 25 degrees C have been studied using a batch adsorption process in terms of a pseudo-second-order equation and three common isotherms (i.e., the Langmuir, Freundlich, and Redlich-Peterson). The pore properties of the Y-type zeolite have been determined using N-2 adsorption-desorption isotherms, indicating that it is a supermicroporous adsorbent associated with a lower percentage of mesopores. Based on the kinetic model the effects of particle size, initial bisphenol-A concentration, initial solution pH, and adsorbent dosage on the adsorption rate constant and equilibrium capacity have been estimated, showing that the adsorption process could be simulated well by the simplified kinetic model. From the data on the equilibrium adsorption capacities obtained by fitting the pseudo-second-order model, the adsorption isotherm could be better described by the three-parameter Redlich-Peterson model than by the two-parameter models (i.e., the Langmuir and Freundlich). (c) 2006 Elsevier Inc. All rights reserved.