Background and purpose: Dexamethasone is one of the most commonly used Glucocorticoids (antibiotics) in medical centers. Conventional treatment methods for removal of Glucocorticoids from wastewaters are not highly efficient, therefore, more effective methods are needed to reduce the entry of these compounds into the environment. The aim of this study was to evaluate the performance of Clinoptilolite zeolite (Cp) in removal of dexamethasone from aqueous solutions, and introducing a suitable isotherm for modeling of the adsorption process.

Materials and methods: In this study, the effect of some parameters including pH of the solution (4, 7 and 9), adsorbent dose (0.2, 0.6 and 1 gr), and contact time (15, 30, 45, 60, 90 and 120 min) were studied on adsorption capacity of Cp. The initial concentration of 5 mgr/l was considered. The isotherm of adsorption process was studied using Langmuir and Freundlich isotherms. The concentration of dexamethasone was measured by UV-visible spectrophotometer. SEM photographs were taken from adsorbent before and after the adsorption process.

Results: The results showed that the maximum adsorption capacity was 1.13 mg/g which was obtained in pH=4, using 0.2 gr adsorbent during 90 min. By increasing the amount of adsorbent, the removal efficiency increased, but adsorption capacity decreased. The specific surface and pores volume of zeolite were 43.91cm²/gr and 0.1717cm³/gr, respectively. The Langmuir model fitted well to the experimental data (R²=0.99).

Conclusion: In this study, Clinoptilolite zeolite was found to be very suitable in removal of dexamethasone from aqueous solutions.