Characterisation of nano-sized particles in chemical mechanical polishing wastewater
by Noor Aina Binti Mohamad Zuki; Norli Ismail; Fatehah Mohd Omar
International Journal of Environmental Engineering (IJEE), Vol. 10, No. 1, 2019

Abstract: Treatment of chemical mechanical polishing (CMP) wastewater and fluoride-containing wastewater in semiconductor manufacturing are conventionally separated. The combined treatment of these two streams of wastewater was studied in terms of zeta potential and z-average hydrodynamic diameter profiles as a function of pH 2 to 12. Optimum pH for CMP wastewater was at pH 6 with zeta potential value of −10 mV and mean particle size of 180 d.nm. Meanwhile, for fluoride-containing wastewater the optimum pH obtained was at pH 9 with zeta potential of 10 mV and mean particle size of 5,214 d.nm. These two streams were combined together at their respective optimum pH and resulted a zeta potential value of 0.55 mV and mean particle size of 12,590 d.nm. Results indicated that the combined treatment for both polishing and fluoride-containing wastewater were beneficial as a larger flocs of fluorosilicate 26(SiF₆²⁻) was generated without the presence of coagulation chemicals. It is proposed that positively charged particles present in fluoride-containing wastewater become adsorbed on the surface of silica nanoparticles in CMP wastewater in which act as nuclei and enhances flocculation since repulsive force of both wastewater is decreased.

Online publication date: Mon, 03-Jun-2019

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