Synthesis and surface characterization of ordered mesoporous silica SBA-15

Ordered mesoporous silica SBA-15 materials were synthesized using Plutonic P123 (non-ionic triblock copolymer EO(20)PO(70)O(20)) as a template under acidic conditions and different heating temperatures and time of the reaction solution These materials were characterized by nitrogen adsorption-desorption measurements Fourier-transformed infrared spectroscopy (FT-IR) and determination of points of zero charge and izoelectric points as well as particle diameters Synthesis at lower temperature (80 C) and longer time of reaction (48 h) gives samples with higher specific surface area (S(BET) = 710 m(2) g(-1)) mesoporose surface (S(meso) = 481 m(2) g(-1)) and narrower pore size distribution Material synthesized at higher temperature (100 degrees C) and shorter time of reaction (24 h) has lower specific surface and mesoporosity (S(BET) = 641 m(2) g(-1) and S(meso) = 367 m(2) g(-1)) At both samples the presence of micropores was confirmed The point of zero charge pH(PZC) = 5 2 +/- 0 2 and the isoelectric point pH(IEB) = 2 3 +/- 0 1 were not affected by synthesis conditions Washing of silica samples in a dilute solution of nitric acid shifts the isoelectric point to a higher value (pH(IEP) = 3 0 +/- 0 2) while the point of zero charge remains constant (C) 2010 Elsevier B V All rights reserve