Adsorption behaviour of estrogenic contaminant, estriol, using Saponin and Brij 35 modified clinoptilolite: equilibrium, kinetic, and thermodynamic studies plus fixed bed modelling

In this study, adsorption affinity of a raw clinoptilolite (RC) modified with Saponin (RC-Saponin) and Brij 35 (RC-Brij) surfactants was investigated to adsorb estriol (E3) from wastewater. The effect of pH, amount of sorbent, contact time, and temperature was evaluated. The results for RC and RC-Saponin confirmed that the Langmuir isotherm had an excellent agreement with the experimental data. However, for RC-Brij, the Freundlich model had excellent correlation with the experimental data. The results indicated that RC-Saponin was a more effective adsorbent compared to the two other samples. Moreover, the lumped technique was used to solve the bed equations, to predict the trend of the breakthrough curve, to obtain model parameters. The agreement between experimental data and kinetic models indicated that the intra-particle diffusion model had a better behaviour compared to other models. The thermodynamic parameters of Gibbs free energy, enthalpy, and entropy changes were obtained.