Cationic MCM-41: synthesis, characterization and sorption behavior towards aromatic compounds

MCM-41 was cationic-modified as an adsorbent for a potentially novel flocculation/sorption system towards the simultaneous removal of dissolved and colloid substances. With the presence of cationic silane as part of silica sources, the cationic-modified MCM-41 (C-MCM-41) was prepared via a direct-synthesis approach using cationic surfactant as a template. The synthesized samples were characterized with X-ray diffraction (XRD), nitrogen adsorption, TEM, FTIR and colloidal titration. The sorption experiments were carried out using benzoic acid and toluene as mimic contaminants. Compared with unmodified MCM-41, the C-MCM-41 with pore size in mesoporous range exhibited increased sorption capacity towards aromatic organic compounds. It was found that the sorption of C-MCM-41 towards organic containments is mainly governed by the population of cationic binding sites and its porosity, although the former is a more portent factor than the latter. During the preparation, the porosity and cationicity of the modified MCM-41 can be manipulated by controlling the removal of the cationic template from the pores, as well as the amount of cationic sources.