Topic
Precipitated silica
About: Precipitated silica is a research topic. Over the lifetime, 1401 publications have been published within this topic receiving 20992 citations.
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TL;DR: In this paper, the effects of extraction time and temperature were closely examined to study the kinetics of the process and the activation energy for silica extraction was 58.20 kJ/mol for the shrinking core model (SCM) with intra-particle diffusion controlled mechanism and the Jander equation can satisfactorily represent the extraction process.
Abstract: The silica extraction from palm oil mill fly ash (POMFA) using sodium hydroxide as one of viable processes for obtaining silica from agricultural waste was investigated. The effects of extraction time and temperature were closely examined to study the kinetics of the process. The fixed variables used in the present work were mass of POMFA 468.2 gram; the POMFA mass to NaOH volume ratio 0.2341 g/cm3; the concentration of NaOH 1.4 N and the stirring speed of 1065 RPM. The levels of temperature employed were 348 K, 358 K, 368 K and 378 K for different time durations up to 60 min. The mechanical fragmentation process was applied to obtain precipitated silica from the extracted silica. The precipitation conditions were: stirring speed of 1160 RPM, pH of 8.75, temperature of 303 K and precipitation time of 100 min. The shrinking core model (SCM) with intra-particle diffusion controlled mechanism and the Jander equation can satisfactorily represent the extraction process. The activation energy for silica extraction was 58.20 kJ/mol for the SCM with intra-particle diffusion and 62.22 kJ/mol for the Jander equation respectively. The precipitated silica agglomerate obtained at the time of 100 min has the median-weighed volume particle size distribution of 114.07 μm. The chemical composition and physical characteristic of precipitated silica which were analyzed with LPSA, XRF, XRD, FTIR and SEM are similar to the precipitated silica from the references.
8 citations
TL;DR: In this paper, the wettability and surface structure of precipitated silica surface loaded trimethylsilyl groups were investigated and it was found that the non-treated sample had micropores.
7 citations
Patent•
01 Aug 2002
TL;DR: In this paper, a mixture consisting of an organopolysiloxane derivative and precipitated silica is produced, and the conditioning of the mixture is performed at 10 to 150 deg.C for 0.5 to 72 hr, and oxidation heating treatment is performed by using an oxidizing gas.
Abstract: PROBLEM TO BE SOLVED: To provide hydrophobic precipitated silica, to provide a production method therefor, and to provide its use. SOLUTION: In the production of the hydrophobic precipitated silica, a) a mixture consisting of an organopolysiloxane derivative and precipitated silica is produced, and b) the conditioning of the mixture is performed at 10 to 150 deg.C for 0.5 to 72 hr, and c) oxidation heating treatment is performed at >300 deg.C by using an oxidizing gas. Thus, the hydrophobic precipitated silica which has a remarkably high whiteness and a remarkably low water absorption percentage can be obtained.
7 citations
TL;DR: A number of new silica fillers have been obtained in the emulsion system and changes in their surface properties appearing as a result of modification with the following alkoxysilanes have been eva...
Abstract: A number of new silica fillers have been obtained in the emulsion system and changes in their surface properties appearing as a result of modification with the following alkoxysilanes have been eva...
7 citations
TL;DR: In this paper, atomic force microscopy was used to study polystyrene-modified silica surfaces produced by admicellar polymerization (polymerization of monomers solubilized in adsorbed surfactant aggregates).
Abstract: Atomic force microscopy was used to study polystyrene-modified silica surfaces produced by admicellar polymerization (polymerization of monomers solubilized in adsorbed surfactant aggregates). The goal was to examine changes in the location and nature of the formed polystyrene resulting from changes in the surfactant and monomer feed levels on precipitated silica. Normal tapping and phase-contrast modes in air were used to image the topography of the polystyrene-modified silica. Moderate-to-light force-tapping mode was used to differentiate between the silica surface and adsorbed water or polymer. The formed polystyrene exists primarily in the pores, with patches extending onto the exposed surface of the silica particles. At moderate tapping forces, darker phase regions were observed in the valleys and pores of the silica in both the modified and the unmodified samples. Upon higher magnification, the darker regions disappear on unmodified silicas, whereas polymer bands become evident on the modified silicas. At lower loadings of surfactant and monomer, the number and extent of polymer patches decreased, with polymer being found only in pores. The polystyrene patches observed inside the valleys of the amorphous silica varied from 1 to 10 nm in thickness. The structure of the polystyrene film formed on precipitated silica was found to be insensitive to the surfactant feed concentration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 290–299, 2003
7 citations