Functionalized graphene oxide-modified sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) based thermal-resistance anti-fouling bi-functional cation exchange membrane for electrodialytic desalination

Abstract

We report a sustainable strategy for fabricating thermal-resistance anti-fouling cation exchange membrane (CEM), using sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (SPPO), and phosphorylated graphene oxide (FGO). The GO was phosphorylated, and different CEMs (3.0–7.0 % weight ratio of FGO) were prepared to investigate their electrodialysis (ED) performance. Structural features of SPPO-FGO composite CEMs such as ̴ 21.51 % degree of sulphonation (SPPO), bi-functional (-SO3H, and -PO3H2) nature, and balanced hydrophobic-hydrophilic segments, etc., were attributed for thermal-resistance and anti-fouling membrane nature of the membrane. The presence of FGO in the SPPO polymer matrix significantly improved mechanical, thermal, oxidative stabilities, ionic conductivity (κm), and counter-ion transport number (tm+). Suitable optimized SPPO-FGO/7 % (7.0 % of FGO) showed excellent physicochemical properties (14.1 % water uptake, 3.2 % swelling ratio, and 1.76 m eq./g ion exchange capacity), along with 10.92 × 10−2 S cm−1 conductivity, and 0.95 counter-ion transport number at 30 °C. Improved i-V curves and ED performance at 60 °C, showed relatively low energy consumption (0.72 k W hr/kg of NaCl removed), and high current efficiency (99.0 %) for SPPO-FGO/7 % CEM revealed, its potential candidature for electrodialytic water desalination. Further, CEM also avoids any significant deterioration in ED performance due to the presence of cationic, anionic and zwitterionic foulants.