Low content nano-polyrhodanine modified polysulfone membranes with superior properties and their performance for wastewater treatment

In this study, PSf ultrafiltration membranes were modified with a low content of polyrhodanine (PRh) nanoparticles to improve the membrane performance for wastewater treatment. Ternary phase diagram evaluation showed that the binodal boundary moved to the solvent-polymer axis by addition of 0.05 wt% PRh nanoparticles and hence the speed of phase separation increased and consequently the membrane porosity improved. Contact angle results confirmed the hydrophilicity enhancement of the membrane surface by addition of PRh nanoparticles to the polymer solution. Furthermore, by addition of the 0.05 wt% PRh nanoparticles to the PSf casting solution, the water and industrial wastewater flux increased from 83 and 70 LMH to 259 and 135 LMH, respectively. Additionally, COD and natural organic matter removal increased from 56.8% and 81.8% to 66.3% and 89.5% respectively. Although increasing the nanoparticle content up to 0.08 wt% had no considerable effect on membrane rejection, the water and industrial wastewater flux decreased to 80 LMH and 64 LMH. Moreover, the modified membranes showed lower irreversible fouling and higher water flux recovery indicating their better antifouling properties. In addition, the membrane containing low contents of PRh nanoparticles demonstrated considerable antibacterial activity.