Kinetics of silica particle formation in nonionic W/O microemulsions from TEOS
dc.contributor.author | Chang, Chia-Lu | en_US |
dc.contributor.author | Fogler, H. Scott | en_US |
dc.date.accessioned | 2006-04-28T15:47:49Z | |
dc.date.available | 2006-04-28T15:47:49Z | |
dc.date.issued | 1996-11 | en_US |
dc.identifier.citation | Chang, Chia-Lu; Fogler, H. Scott (1996)."Kinetics of silica particle formation in nonionic W/O microemulsions from TEOS." AIChE Journal 42(11): 3153-3163. <http://hdl.handle.net/2027.42/37436> | en_US |
dc.identifier.issn | 0001-1541 | en_US |
dc.identifier.issn | 1547-5905 | en_US |
dc.identifier.uri | https://hdl.handle.net/2027.42/37436 | |
dc.description.abstract | The kinetics of silica particle formation by the ammonia-catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) in water-in-oil (W/O) microemulsions containing a nonionic surfactant was investigated using Fourier-transform infrared spectroscopy, transmission electron microscopy, and light-scattering techniques. The results show that TEOS hydrolysis and silica-particle growth occur at the same rate, indicating the growth of silica particles is rate-controlled by the hydrolysis of TEOS. The rate of TEOS hydrolysis in microemulsions is first order with respect to the concentration of aqueous ammonia (29 wt. % NH 3 ), but depends weakly on the concentration of water. Based on the fact that TEOS hydrolysis follows a nucleophilic (S N 2) substitution of the TEOS's ethoxy group with hydroxyl ion, the kinetic data suggest that both water and ammonia remain predominately in W/O microemulsion droplets. The rate of TEOS hydrolysis also depends on the surfactant concentration that controls the molecular contact between hydroxyl ions and TEOS in the solution. Due to the reaction-controlled growth mechanism, the silica-particle size distribution retains virtually the same shape over the growth period. The final average size of silica particles can be varied from 26 to 43 nm by adjusting concentrations of water and surfactant. Increasing the water concentration decreases the average size and uniformity of silica particles. For a given water concentration, the smallest and most uniform silica particles are produced at intermediate water-to-surfactant molar ratios (about 1.9). The results are discussed in terms of the effect of water concentration on the stability of the hydrolyzed silica reacting species during the nucleation of particles and of the water-to-surfactant molar ratio on the compartmentalization of silica species in microemulsions. | en_US |
dc.format.extent | 1556518 bytes | |
dc.format.extent | 3118 bytes | |
dc.format.mimetype | application/pdf | |
dc.format.mimetype | text/plain | |
dc.language.iso | en_US | |
dc.publisher | American Institute of Chemical Engineers | en_US |
dc.publisher | Wiley Periodiocals, Inc. | en_US |
dc.subject.other | Chemistry | en_US |
dc.subject.other | Chemical Engineering | en_US |
dc.title | Kinetics of silica particle formation in nonionic W/O microemulsions from TEOS | en_US |
dc.type | Article | en_US |
dc.rights.robots | IndexNoFollow | en_US |
dc.subject.hlbsecondlevel | Chemical Engineering | en_US |
dc.subject.hlbtoplevel | Engineering | en_US |
dc.subject.hlbtoplevel | Science | en_US |
dc.description.peerreviewed | Peer Reviewed | en_US |
dc.contributor.affiliationum | Dept. of Chemical Engineering, The University of Michigan, Ann Arbor, MI 48109 | en_US |
dc.contributor.affiliationum | Dept. of Chemical Engineering, The University of Michigan, Ann Arbor, MI 48109 ; Dept. of Chemical Engineering, The University of Michigan, Ann Arbor, MI 48109 | en_US |
dc.description.bitstreamurl | http://deepblue.lib.umich.edu/bitstream/2027.42/37436/1/690421115_ftp.pdf | en_US |
dc.identifier.doi | http://dx.doi.org/10.1002/aic.690421115 | en_US |
dc.identifier.source | AIChE Journal | en_US |
dc.owningcollname | Interdisciplinary and Peer-Reviewed |
Files in this item
Remediation of Harmful Language
The University of Michigan Library aims to describe library materials in a way that respects the people and communities who create, use, and are represented in our collections. Report harmful or offensive language in catalog records, finding aids, or elsewhere in our collections anonymously through our metadata feedback form. More information at Remediation of Harmful Language.
Accessibility
If you are unable to use this file in its current format, please select the Contact Us link and we can modify it to make it more accessible to you.