Eggshell as a New Biosorbent for the Removal of Pharmaceuticals From Aqueous Solutions

Abstract

The suitability of chicken eggshell as a novel sorbent for removal of pharmaceuticals (dexamethasone (DEX), febantel (FEB), praziquantel (PRAZ), procaine (PROC), and tylosin (TYL)) from water is investigated. Batch sorption experiments are performed to detect the effect of the initial concentration of pharmaceuticals, contact time, and temperature on the eggshell sorption capacity. The eggshell sample is characterized using Fourier transform IR spectroscopy, scanning electron microscopy combined with energy dispersive spectroscopy, and with particle and pore size distribution analyses. Equilibrium data are analyzed using Freundlich and Dubinin–Radushkevich isotherms. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) are calculated in order to predict the sorption nature. The results indicate that the sorption process is spontaneous and exothermic for PROC; spontaneous and endothermic for DEX, FEB, TYL; and non‐spontaneous and exothermic for PRAZ. According to the experimental results, chicken eggshell as mesoporous sorbent can be successfully used as an alternative and low‐cost biosorbent. The kinetic experimental data are fitted by Lagergren's and Ho's pseudo‐second‐order model. Kinetic parameters, rate constants, equilibrium sorption capacities, and correlation coefficients are estimated and discussed for both kinetic models. The pseudo‐second‐order model is suitable for prediction of sorption capacities. The mechanism of the sorption process is determined by the Weber–Morris intraparticle diffusion model and Boyd model. The sorption rate of investigated pharmaceuticals to chicken eggshells is influenced by both diffusion types: intraparticle and film diffusion.