MCM-41

About: MCM-41 is a research topic. Over the lifetime, 2355 publications have been published within this topic receiving 91416 citations.

Photocatalytic degradation of orange II by TiO2 catalysts supported on adsorbents

Abstract: TiO 2 mediated semiconductor photocatalysis is an established advanced oxidation process for the treatment of contaminated aqueous and gaseous streams. However, TiO 2 exhibits low adsorption ability, especially for non-polar substances due to its polar structure. Low adsorption ability of non-porous TiO 2 particles can be improved by surface augmentation using inert supports. In this work, TiO 2 was impregnated on three different kinds of adsorbents, mesoporous (MCM-41), microporous (β-zeolite) and pillared structure (montmorillonite) where different loadings (10-80%) of TiO 2 were obtained using sol-gel method. The catalysts were characterized by several analytical techniques including XRD, SEM-EDX, XPS, and BET analyzer. Subsequent to the dark adsorption studies, photocatalytic efficiency of the supported catalysts was evaluated using an azo-dye, orange II in water as model compound under different operating conditions. All supported catalysts exhibit good photodegradation efficiency of orange II, and their overall removal efficiency was always better than that of bare TiO 2 produced by the sol-gel method and commercial catalyst, Degussa-P25.

Analysis of Heavy Metal Toxic Ions by Adsorption onto Amino-functionalized Ordered Mesoporous Silica

Abstract: Ordered mesoporous silica (MCM-41) materials with different textural properties were prepared using alkyl (dodecyl, cetyl, eicosane) trimethyl ammonium bromide (DTAB, CTAB, ETAB, respectively) as structure directing surfactants, functionalized with amine groups and used as adsorbent for the toxic metal ions, Cr (VI), As (V), Pb (II) and Hg (II). Amino functionalization of mesoporous MCM-41 was achieved by co-condensation of N-[3-(trimethoxysilyl)-propyl] aniline with tetraethyl orthosilicate. Adsorption isotherm and adsorption capacity of the amine functionalized materials for Cr (VI), As (V), Pb (II) and Hg (II) ions were followed by inductively coupled plasma mass spectrometry (ICP-MS). Results demonstrate that amine functionalized MCM-41 prepared with ETAB showed higher adsorption capacity for Cr (VI), As (V), Pb (II) and Hg (II) ions in comparison to MCM-41 prepared with CTAB and DTAB. The higher adsorption capacity for MCM-41(ETAB) was correlated with amine content in the material (determined by CHN analysis) and relative decrease in pore volume and pore diameter. X-ray diffraction (XRD) analysis, nitrogen adsorption-desorption measurements and Fourier Transform infrared spectrometry (FTIR) were used to follow the changes in the textural parameters and surface properties of the mesoporous materials as a result of amine functionalization to correlate with the adsorption characteristics. The adsorption process was found to depend on the pH of the medium.