New composite aerogel-like adsorbents for thiophene based on π-complexation

The Cu2O-SiO2-50, NiO-SiO2-23 and Ag2O-SiO2-50 composite aerogels-like materials were prepared by sol-gel synthesis followed by ambient pressure drying technology. Their adsorption performance and mechanism for thiophene from model gasoline were investigated by equilibrium and breakthrough adsorption experiments, respectively. The results show that the adsorption equilibrium data of thiophene over the three samples were more in line with the Langmuir and Freundlich isotherms compared to the Temkin isotherm. The adsorption equilibrium data of thiophene on Ag2O-SiO2-50 composite aerogel-like adsorbent were well-fitted to both Langmuir and Freundlich isotherms; the value of the Freundlich constant 1/n is very close to 1, indicating that its surface energy is relatively homogeneous. For three samples, both breakthrough adsorption capacity and maximum monolayer adsorption capacity decreased in the order of Ag2O-SiO2-50 > Cu2O-SiO2-50 > NiOSiO2-23, and were 17.10, 5.06, 1.37 mgS/g and 54.23, 17.39, 6.04 mgS/g, respectively. For three samples, the Ag2O-SiO2-50 composite aerogel-like adsorbent exhibited the best adsorption performance for thiophene, attributed to its bigger surface area, high porosity, highly homogeneously dispersed Ag+ species although the less active adsorption sites compared to the other two. The adsorption of thiophene on composite aerogels-like adsorbents was mainly controlled by the n-complexation between thiophene and adsorbents. Ag2O-SiO2-50 exhibited a better reusability through benzene-n-heptane solvent washing.