Sorption of 17α-Ethinylestradiol by Surfactant-Modified Zeolite-Rich Tuff from Aqueous Solutions

The sorption behavior of 17α-ethinylestradiol by a surface-modified zeolitic tuff with hexadecyltrimethylammonium (HDTMA) was investigated. The zeolitic material (clinoptilolite) was treated with 0.1 M of sodium chloride solution and then with 25 and 50 mM of HDTMA solutions. The sorption kinetics shows that the maximum removal percentage of 96.87 % was reached at 36 h for the zeolite with 25 mM HDTMA, while with 50 mM of HDTMA, the maximum removal of 98.34 % was achieved at 44 h. Furthermore, pseudo-first-order, pseudo-second-order, and Elovich models were analyzed and the kinetic data exhibited a good fit with the pseudo-second-order model, indicating that the sorption mechanism is chemisorption. The isotherms for the sorption of 17α-ethinylestradiol showed that sorption capacity was 0.7073 and 0.6943 mg/g for 25 and 50 mM, respectively, at 25 °C and showed a partition mechanism. Moreover, the pH influence on the sorption process was studied and the sorption capacity was increased as the pH decreases.