In this study, adsorption of cetylpyridinium chloride (CPC), a cationic surfactant, on pyrite surface was investigated. Maximum adsorption capacity of pyrite for CPC was 357 mmol kg-1 in pyrite suspension (4 g L-1) at pH 7. Zeta potential (?) of pyrite surface showed increasing positive values (i.e., 5 to 18.5 mV at pH 5 and 8.12 to 26 mV at pH 6) as CPC adsorption proceeded in the suspension at pH < 7. However, at pH = 7, it changed from negative to positive value (i.e., -5 to 36 mV at pH 7, -10 to 30 mV at pH 8, and -15 to 20 mV at pH 9), indicating three different iso-electric points at each pH. The decrease of CPC adsorption capacity was observed by addition of NaCl (0.01 and 0.1 M) at suspension pH 5 and 7 due to the excessive Cl- ions near pyrite surface. ? of pyrite surface changed from positive to negative value by the addition of NaCl (21 to -16 mV at pH 5 and 5 to -22 mV at pH 7) by counter-ions (Cl- from both CPC and NaCl). This study provides basic understanding of the adsorption mechanism of cationic surfactant on pyrite surface at different pH conditions when surfactant-washed wastewater and contaminated groundwater need to be treated by the reactive iron sulfide.

Adsorption of cationic cetylpyridinium chloride by pyrite

243rd National Meeting (2012)

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