Chinese Journal of Chemistry, 2009, 27, 2171—2174 Full Paper * E-mail: hsepehrian@yahoo.com; Fax: 0098-21-88820993 Received March 2, 2009; revised and accepted July 3, 2009. © 2009 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Modified Mesoporous Silicate MCM-41 for Zinc Ion Adsorption: Synthesis, Characterization and Its Adsorption Behavior SEPEHRIAN, Hamid* ,a WAQIF-HUSAIN, Syed b RAKHSHANDERU, Farrokh c KAMEL, Leila c a Nuclear Fuel Cycle Research School, Nuclear Science and Technology Research Institute, AEOI, P.O. Box 11365/8486, Tehran, Iran b Department of Chemistry, Faculty of Science, Science and Research Branch, Islamic Azad University, P.O. Box 14515-775, Poonak-Hesarak, Tehran, Iran c Chemistry Faculty, University of Tarbiat Moallem, 49-Mofateh Avenue, Tehran-15614, Iran Modified MCM-41 has been prepared by bi-functionalization of thiol and amino functional groups onto mesoporous silicate MCM-41. Elemental analysis (EA), thermogravimetry analysis (TGA) and FTIR techniques were used to quantify the attachment of the thiol and amino functional groups to the mesoporous silicate pore wall. Powder X-ray diffraction (PXRD) and nitrogen adsorption techniques were used to establish the pore diameter, packing of the pores and specific surface area of the modified mesoporous silicate MCM-41. Adsorption behavior for 18 metal ions on this sorbent has been studied and discussed. This sorbent has high affinity for zinc ions against amino- or thiol-functionalized MCM-41 sorbents. Keywords mesoporous, MCM-41, bi-functionalization, amino, thiol, metal ion adsorption Introduction Among the wide variety of functionalized mesopor- ous materials, organically functionalized moieties have generated much interest in terms of their application to catalysis, sensing, and separation, because of their high surface area and large ordered pores ranging from 20 to 300 Å with narrow pore-size distribution. In particular, the design of mesostructure-based adsorbents for the removal of toxic heavy metal ions from aqueous solu- tion is a subject that has been intensively investigated. 1-5 The effective sorption of Cu 2＋ ions has been reported, using a variety of mesoporous materials immobilized with organosilanes containing nitrogen atom moieties such as aminopropyl, ethylenediamine, and diethyl- enetriamine groups. 2,4,6 The thiol-derivated HMS, MCM-41, and SBA-15 materials are capable of quanti- tatively adsorbing Hg 2＋ from different types of waste streams. 1,7 The polymeric adsorbents derivatized from imidazole and thiol functional groups have been used in noble metal separation. 8-10 Following our work on the synthesis of new modified mesoporous sorbents, 11 in this paper, we report the synthesis of amino-thiol-func- tionalized mesoporous silica MCM-41, its properties and sorption behavior for 18 metal ions. Experimental Reagents All the chemicals used were of analytical grade from Merck, except cetyltrimethylammonium bromide (CT- AB) and (3-mercaptopropyl)trimethoxysilane (MPTS), (3-aminopropyl)triethoxysilane (APTES) which were supplied by Aldrich (UK). Apparatus A Philips X'pert powder diffractometer system with Cu-Kα (λ＝1.541 Å) radiation was used for X-ray stud- ies. XRD analysis was performed from 1.5° to 10.0° (2θ) at a scan rate of 0.02 (°)/s. Nitrogen adsorption studies were made with a Quantachrome NO-VA 2200e in- strument. Nitrogen adsorption isotherm was determined at 77 K and specific surface area by applying the BET equation to the isotherm. 12 The pore size distribution was calculated using the adsorption branch of the iso- therm and the Barrett-Joyner-Halenda (BJH) formula. 13 FT-IR spectrum was recorded using a Bruker FT-IR spectrophotometer of model Vector-22 by a standard KBr disc technique. Thermogravimetric analysis was performed on a Rheometric Scientific model STA-1500 instrument. The thermogravimetric analysis of various samples was performed from ambient temperature to 900 ℃ at a heating rate of 10 ℃ /min. Elemental analysis of sorbent was done using an Elementar CHNOS analyzer of model Vario EL III. pH measure- ments were made with a Schott CG841 pH-meter (Ger- many). Quantitative determinations of inorganic ions were carried out using an inductively coupled plasma-optical emission spectroscope (ICP-OES) of