The aim of this study was to remove a known pharmaceutics, dexamethasone, from an aqueous solution using clinoptilolite zeolite (CP). CP is a natural, versatile and inexpensive mineral, which has been investigated and applied in the last few decades. Herein, the experiments were carried out in the common conditions of a batch system in room temperature, and the effects of some parameters such as pH of the solution, initial concentration of dexamethasone, adsorbent dose and contact time were studied. Kinetic and isotherm of adsorption processes of dexamethasone on CP were surveyed in the current study. Results revealed that the maximum efficiency (78 %) occurred in pH = 4. The adsorption process followed a pseudo-second-order kinetic model as well as Freundlich and Sips isotherm models fitted with the experimental data well.

a b s t r a c tThe present study investigated the ability of clinoptilolite zeolite (CP) for removal of dexamethasone from aqueous solutions. The effects of some factors such as adsorbate concentration, adsorbent dosage, pH and contact time had been studied. Determination of dexamethasone was performed using UV-visible spectrophotometer. Four isotherm models including Freundlich, Langmuir, Tempkin and Sips were evaluated using linear and non-linear regression analysis. Results showed that in acidic condition (pH 4), the efficiency reached to maximum (57%) and linear regression had better performance for analyzing the experimental data. The Langmuir model is better than other isotherms to represent equilibrium data in both linear and non-linear methods.