Physical and chemical characterisation of some silicas and silica derivatives

Abstract

An extensive study of lbur types of porous silica supports has been performed, with particular emphasis on their physical and morphological characteristics. These silicas were modified by reacting the surface silanol groups present with either 3-(trimethoxysilyl)propylmethacrylate or 3-glycidoxypropyltrimethoxysilane or 3-aminopropyltriethoxysilane, to produce derivatives with suitable functional groups for further utilisation in the immobilisation of biological compounds. The silicas and their derivatives used were fully characterised with regard t,~ particle size distribution (laser light scattering), specific surface area (BET method), pore size distribution (gas adsorption and mercury porosimetry), density (helium pycnometry), yield of grafting (TGA) and chemical composition (FTIR/DRIFT).

Structural and Chemical Characterization of Silica Spheres before and after Modification by Silanization for Trypsin Immobilization

“…Bands between 1100 and 960 cm −1 relate to silica and can be found in both spectra (Si-O-Si and Si-O-H stretching, resp.). Transmittance bands at about 3455, 3010, 2969, and 2940 cm −1 appear only in silanized silica sample, resulting from APTS chemical modification process, similar to those assignments from Ramos et al [26]. Water adsorption presence was evidenced by 3455 cm −1 band, especially in silanized silica, together with amino group bands (N-H bound, 1560 cm −1 ).…”

Nanosized TiO2—A promising catalyst for the aldol condensation of furfural with acetone in biomass upgrading

“…The number of surface OH groups can be determined by various methods such as infrared spectroscopy [39][40][41][42], ion-exchange reaction [41], titration procedures [42][43][44][45] and nuclear magnetic resonance [46,47]. In addition, thermal gravimetric analysis is often used to estimate the number of OH groups on the surface as it is a simple and fast method compared to the other techniques [40,43,47,48].…”

Enzyme-linked immunofiltration assay used in the screening of solid supports and immunoreagents for the development of an azinphos-methyl flow immunosensor

“…A very important parameter is the pore size diameter, which influences the access of the biological compound to the inner part of the porous material. From this characterization a bimodal distribution of pore sizes was detected by mercury porosimetry (Ramos et al, 1998). These authors found that the mean pore diameter of 100 nm indicated by the manufacturer lacks any physical meaning since, in fact, the sample presented two peaks at 13 and 120 nm, respectively.…”

“…Pore size determination was performed by mercury intrusion/extrusion by using a Micromeritics Poresizer 9320 Mercury porosimeter. All this methodology is very well described by Ramos et al (1998).…”