title: Silica particles settling characteristics and removal performances of oxide chemical mechanical polishing wastewater treated by electrocoagulation technology.
abstract: The purpose of this study was to explore the feasibility of removing silica particles and reducing turbidity from oxide chemical mechanical polishing (oxide-CMP) wastewater. Based on the dynamic characteristics of batch electrocoagulation, three operating stages (lag, reactive, and stabilizing) are proposed to identify the relationships among the zeta potential of the silica particles, solution turbidity, and the corresponding mean particle size of the silica. Experimental results show that the silica particles were destabilized and settled at the critical mean particle size, which was estimated to be above 520nm after 10min, and the corresponding turbidity removal mostly occurred during the reactive stage. Furthermore, the corresponding mean particle size varied from 520 to 1900nm as the treatment time progressed from 10 to 20min, which also occurred during the reactive stage. Several parameters, including different electrode pairs, electrolyte concentration, applied voltage, and the optimum condition of power input were investigated. Experimental results indicate that a Fe/Al electrode pair is the most efficient choice of the four electrode pair combinations in terms of energy consumption. The optimum electrolyte concentration and applied voltage were found to be 200ppm NaCl and 30V, respectively.
authors.affiliation: Department of Safety Health and Environmental Engineering, Chung Haw University of Medical Technology, Tainan Hsien 717, Taiwan.
authors.forename: Chih-Ta
authors.initials: CT
authors.lastname: Wang
authors.forename: Wei-Lung
authors.initials: WL
authors.lastname: Chou
authors.forename: Li-Shien
authors.initials: LS
authors.lastname: Chen
authors.forename: Shih-Yu
authors.initials: SY
authors.lastname: Chang
mesh_terms: D004564:Electrocoagulation / Q000295:instrumentation* / Q000379:methods*; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D010087:Oxides / Q000737:chemistry* / Q000302:isolation & purification*; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000295:instrumentation* / Q000379:methods*
chemical_list: D010087:Oxides; D012822:Silicon Dioxide