Impact of Peroxydisulfate in the Presence of Zero Valent Iron on the Oxidation of Cyclohexanoic Acid and Naphthenic Acids from Oil Sands Process-Affected Water

Large volumes of oil sands process-affected water (OSPW) are produced during the extraction of bitumen from oil sands in Alberta, Canada. The degradation of a model naphthenic acid, cyclohexanoic acid (CHA), and real naphthenic acids (NAs) from OSPW were investigated in the presence of peroxydisulfate (S2O82-) and zerovalent iron (ZVI). For the model compound CHA (SO mg/L), in the presence of ZVI and 500 mg/L S2O82-, the concentration decreased by 45% after 6 days of treatment at 20 degrees C, whereas at 40, 60, and 80 degrees C the concentration decreased by 20, 45 and 90%, respectively, after 2 h of treatment. The formation of chloro-CHA was observed during ZVI/S2O82- treatment of CHA in the presence of chloride. For OSPW NAs, in the presence of ZVI alone, a 50% removal of NAs was observed after 6 days of exposure at 20 degrees C. The addition of 100 mg/L S2O82- to the solution increased the removal of OSPW NAs from SO to 90%. In absence of ZVI, a complete NM removal from OSPW was observed in presence of 2000 mg/L S2O82- at 80 degrees C. The addition of ZVI increased the efficiency of NAs oxidation by S2O82- near room temperature. Thus, ZVI/S2O82- process was found to be a viable option for accelerating the degradation of NAs present in OSPW.