Adsorption of Aqueous Mercury(II) on Propylthiol-Functionalized Mesoporous Silica Obtained by Cocondensation

Adsorption of inorganic mercury(II) from an aqueous solution on mercaptopropyl-functionalized SBA-15 mesoporous silicas has been investigated. Adsorbents were prepared by the cocondensation method using tetraethoxysilane and different quantities of (mercaptopropyl)trimethoxysilane. Pluronic P123 was employed as a structure-directing agent. Mercury adsorption isotherms at 20 (degree)C are reported for every synthesized material. The maximum mercury loading has been obtained from Langmuir fitting. Stoichiometric ratios of 1:1 S-Hg have been observed in all cases. Adsorbents were extremely efficient in removing inorganic mercury from an aqueous solution with a maximum in mercury loading of ca. 2.9 mmol of Hg g-1 for the material with the higher organic content. The effect of the pH on mercury adsorption has been studied. The efficiency of the adsorbents has been found to remain almost constant from neutral pH up to 3 M nitric acid concentration.