Abstract:
Porphyrin doped mesoporous silica were prepared by the sol-gel route using tetraethoxysilane (TEOS) as a silica precursor, cetyltrimethylammonium bromide (CTAB) as a template and sodium hydroxide as a catalyst. Two types of porphyrin, namely meso- tetraphenylporphyrin (TPP) and meso-tetrakis (p-nitrophenyl) porphynn (TNPP) were used as doping molecules. The amount of incorporated TPP and TNPP were 7.1 and 7.2 µmole per 1 mole of TEOS, respectively. The morphology studied from SEM technique indicated the spherical particle of mesoporous silica with an average diameter of 0.4 µm. The physical properties of porphyrin doped mesoporous silica such as crystallinity, mesoporosity and surface area were characterized using X-ray diffraction and nitrogen sorption techniques. The results suggested the high surface area, large pore volume and narrow pore size distribution of all materials. In addition, these silica were mesostructure and had good ordered arrangement. The ability of porphyrin doped mesoporous silica to extract Cd(II), Cu(II), Fe(II), Fe(III), Ni(II), Pb(II) and Zn(II) were evaluated. The extent of metal extraction were found to be dependent on the presence of salts including NaNO₃ and NaCl, in metal solution. The effect of silica mass and initial pH of metal solution on the extraction of Cd(II), Ni(II) and Pb(II) were also investigated. The desorption of these metals was possible with 0.1 M HNO₃.