(635g) Naphthenic Acids Removal from High Tds Produced Water By Persulfate Mediated Iron Oxide Functionalized Catalytic Membrane, and By Nanofiltration

Increasing stress on the existing water resources necessitates advancement in water treatment technology. During oil extraction process, oil industries generate large amounts of produced water containing organic contaminants, such as naphthenic acids (NA) and very high concentrations of inorganic salts. Recovery of potable water from such water is highly energy intensive due to its high salt concentration. Here, we explored catalytic properties of iron oxide (Fe_xO_y) functionalized membranes in oxidizing NA from water containing high concentrations of total dissolved solids (TDS) using persulfate as an oxidizing agent. Catalytic decomposition of persulfate by Fe_xO_y functionalized membranes followed pseudo-first order kinetics with an apparent activation energy of 18 Kcal/mol. Fe_xO_y functionalized membranes were capable of lowering the NA concentrations to less than discharge limits of 10 ppm at 40 ^OC. Oxidation state of iron during reaction was quantified. Membrane performance was evaluated for extended operating period. Coupled nanofiltration–functionalized membrane was evaluated. Commercially available nanofiltration membranes were investigated to selectively retain NA from water containing high concentrations of dissolved salts. Commercial NF membranes, NF270 (Dow) and NF8 (Nanostone) had NA rejection of 79% and 82%, respectively. The developed Fe_xO_y functionalized membrane can then treat the lower volume concentrated NF stream (retentate) for efficient removal of NA.