Production of silica particles by membrane emulsificatio

Goran Vladisavljevic (1253448)

M.A.S. Valdes (7130417)

Marijana M. Dragosavac (7127981)

Michael T. Stillwell (7128413)

R.G. Holdich (7126133)

English

Loughborough University Institutional Repository

   This item was submitted to Loughborough’s Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions.      For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/  Production of silica particles by membrane emulsification  Marijana M. Dragosavac1, Richard G Holdich1, Goran T. Vladisavljević1, Miguel Angel Suarez Valdes2 and Michael T. Stillwell3  1Chemical Engineering, Loughborough University, Loughborough, UK 2Chemical Engineering and Environmental Technology, University of Oviedo, Oviedo, Spain 3Micropore Technologies, Hatton, Derby, DE65 5DU Keywords: membrane emulsification, silica particles, Dispersion cell, emulsion In the last few years there has been increasing interest in the production of porous inorganic materials with high surface area. Such materials have potential application in various fields of catalysis, separation, sorption, bioreactor, sensors and so on. Silica is an inorganic material that does not swell and with its good mechanical and thermal stability it can be used in various solvents and have wide applications. In the literature silicon alkoxide or tetraetoxisilane are mainly used as silica sources. The main drawback of using such materials is that they are expensive and therefore production of large quantities of silica would not be cost effective. In this work silica particles were successfully produced from precursor sodium silicate droplets using membrane emulsification. In membrane emulsification monosized emulsion is produced by injecting one liquid phase (e.g. water) through microporous membrane into a second immiscible liquid phase (e.g. kerosene).  The droplet size is mainly controlled by the shear stress applied on the membrane surface and the pore size (Vladisavljević and Williams 2005). The Dispersion Cell (Kosvintsev et. al 2005) with a hydrophobic nickel membrane attached on the bottom of the cell (Fig. 1 a,b) was used to generate emulsion. A mixture of sodium silicate (silica source) and sulphuric acid (gel-forming reagent) was used as dispersed phase and kerosene containing 2% Span 80 was used as a continuous phase.    Figure 1. (a) Hydrophobic nickel membrane with 15 µm pores and (b) Dispersion Cell both kindly provided by Micropore Ltd. UK. (c) SEM of calcined silica particles with a mean size of  In most of the experiments flux of the dispersed phase was kept constant at 350 L m-2 h-1. It is widely accepted that the shear stress on the membrane surface has to be applied in order to get uniform droplets. In the Dispersion cell the shear stress is induced with the paddle stirrer place on top of the membrane. By changing the shear stress on the membrane surface liquid silica droplets in the range between 50 and 160 µm were produced. After solidification of silica the particles were washed and dried at room temperature followed by calcination at 550°C. After final drying the size of the produced silica particles was in the range between 30 and 70 µm (Fig. 1c). BET specific surface area of the produced silica after calcination was found to be 750 m2/g while the average pore diameter was 1.3 nm. (a) (b) (c)600 µmAcknowledgment The authors wish to acknowledge the financial support of the UK Engineering and Physical Sciences Research Council. The work was undertaken as part of the DIAMOND project into Decommissioning, Immobilisation And Management Of Nuclear wastes for Disposal.  References   Kosvintsev S.R, Gasparini G., Holdich R.G., Cumming I.W, Stillwell M.T., Liquid−Liquid membrane Dispersion in a Stirred Cell with and without Controlled Shear, Industrial and Engineering Chemistry Research , 44, 2005, 9323.  Vladisavljević, G.T. and Williams, R.A., Recent developments in manufacturing emulsions and particulate products using membranes, Advances in Colloid and Interface Science, 113, 2005, 1.   

Production of silica particles by membrane emulsification

https://repository.lboro.ac.uk/articles/Production_of_silica_particles_by_membrane_emulsification/9246089/files/16829948.pdf

Production of silica particles by membrane emulsification

Abstract

Similar works

Full text

Available Versions

Loughborough University Institutional Repository