The effects of magnetic particles and polyaluminum chloride on silica aggregation in chemical mechanical polishing wastewater
| Autor: | Bo - Sheng, 王柏勝 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 As booming development of semiconductor industry, wastewater produced containing substantial quantities of fine abrasive particles is considerable. In recent years, magnetic particles aggregation in wastewater treatment is applied gradually, using the magnetic field to attract deposition after the absorption of magnetic particles. The results show that the best effect of polyaluminum chloride (PAC) coagulant is at pH = 6, and doses up to 0.08 g L-1 .Because of the smaller particle size of magnetic particles have a large adsorption surface area relatively at pH=4, and opposite electric charge of zeta potential between silica and magnetic particles. It has better effect owing to the attraction of opposite magnetic poles. The best effect of magnetic particles is at pH = 4, and doses up to 3.74 g L-1. When magnetic particles are not enough, whole electrical poles of particle group after adsorption are still negative owing to the silica. Magnetic particles and silica float around the mixed liquid because the repulsion. When magnetic particles are too much, whole electrical poles of particle group after adsorption become positive electrode owing to the magnetic particles. Only in the appropriate dosage, magnetic particles and silica have charge neutralization. At this moment, it has the best effect because of the electrical poles of particle group are so weak even zero that it can aggregate each other by slow stir or the Brownian movement. Using PAC coagulant with magnetic particles treat the wastewater has the better effect than each does things in its own way. In 1000 mL wastewater, the dosage of PAC coagulant can be reduced one half when added to magnetic particles 2.49 g L-1; It can be reduced 75% when magnetic particles doses up to 3.74 g L-1. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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