Ti₃C₂Tₓ MXene-Tuned polyamide crosslinking and surface hydrophilicity for enhanced antifouling in forward osmosis treatment of hypersaline produced water

Forward osmosis (FO) is considered to be a promising choice for hypersaline oily produced water treatment, but membrane fouling and concentration polarization compromise its performance. In this study, Ti 3 C 2 Tx MXene nanosheets with different concentrations (0.05-0.15 wt.%) were incorporated into the polyamide layer during interfacial polymerization to prepare thin-film nanocomposite (TFN)FO membranes. The 0.1 wt.% loading (MX3) was identified as optimal; it showed the smoothest surface compared to the pristine TFC (Sa=17.19 vs. 74.82 nm), the highest estimated crosslinking degree derived from the O/N ratio in the EDS result (57.46 vs. 35.72%), and a lower water contact angle than the pristine TFC membrane (43.9° vs. 52°). MX3 demonstrated a two-fold higher flux and lower reverse salt flux than TFC. When synthetic produced water (76 g/L NaCl, 500 mg/L emulsified kerosene) was used as feed and 5 M NaCl was used as draw solution, MX3 showed a flux of (6.09 ± 0.3 LMH) with a reverse salt flux between (1.4-1.6 g·m -2 ·h -1 ), whereas TFC showed a flux of (2.98 ± 0.2 LMH) and RSF between (2.45-2.76 g·m -2 ·h -1 ). MX3 showed (99.54 ± 0.2 %) oil rejection during FO, compared to (⁓98.7 %) for TFC. Concentration polarization showed that dilutive internal concentration polarization remained the major resistance for both membranes, and the resistance value for MX3 was larger than TFC because of its higher flux. A30-h test of six fouling cycles and hydraulic cleaning revealed that both membranes experienced fouling as progressive irreversible flux loss. However, in the testing, MX3 showed a lower rate of accumulated flux deterioration, resulting in 33.04 vs 74.06 % flux decline, with a corresponding normalized flux (J/J 0 ) of 0.67 vs 0.26 for the TFC membrane, respectively.