00000ctm a22000004i 4500 UP-99796217610586555 Buklod 20130125103107.0 m |o d | ta 130125s2012 xx d r |||| u| (iLib)UPD-00194803453 DARCHIVES rda eng DMLUC LG 995 2012 M37 C67 Corpuz, Ryan D. author. Electrophoretic classification of ultrafine silica particles in dilute aqueous suspension by Ryan D. Corpuz. 2012. xi, 160 leaves illustrations (some color) text rdacontent unmediated rdamedia volume rdacarrier Thesis (M.S. Materials Science and Engineering)--University of the Philippines, Diliman. This study aims to classify ultrafine silica particles in a dilute aqueous suspension using their electrokinetic properties. Initially, the electrophoretic mobility of three (3) silica particle grades with mean diameters 2.39 µm, 3.74 µm and 5.31 µm are determined from pH 3 to 10 using two (2) electrolyte concentrations (0.01 M and 0.001 M KNO3). To evaluate classification of silica particles, both electrophoresis and electrophoretic deposition experiments are performed using a modified electrophoretic deposition (EPD) cell. Both experiments are conducted at pH 10 with an electrolyte concentration of 0.001 KNO3 in four (4) time intervals (15, 20, 25 and 30 min). Results show that the electrophoretic mobility (µm.cm/Vs) of ultrafine silica particles in aqueous suspension decreased with increasing particle size. Electrophoretic mobilities also increased with increasing pH, and decreased with a corresponding increase in electrolyte concentration. Moreover, using the modified EPD cell, the onsets of deposition/migration time as well as the direction of deposition and migration are readily determined. Furthermore, classification experiments through electrophoresis and electrophoretic deposition (EPD) show a comparable gradient in both mean particle diameter and particle size distribution with increasing migration and deposition time. The result are as follows: a) at 15 minutes, the mean particle diameter is 2.24 µm for EPD and 2.35 µm for electrophoresis; b) at 20 minutes, the mean particle diameter is 3.01 µm for EPD and 3.3 µm for electrophoresis; c) at 25 minutes, the mean particle diameter is 3.9 µm for EPD and 4.06 µm for electrophoresis; and, d) at 30 minutes, the mean particle diameter is 4.88 µm for EPD and 5.17 µm for electrophoresis. Based on the observed gradient in particle size and particle size distribution, it shows that the presence of smaller particles in the early stage of migration is probably due to their higher electrophoretic mobility as compared to the larger particles, thus resulting to their classification. Electrophoretic deposition. Silicate minerals Classification. Laser diffraction. Scanning electron microscopy (SEM). FI UP UPD DARCHIVES LG 995 2012 M37 C67 UPD DENG-II LG 995 2012 M37 C67 Thesis