Facile synthesis of PTU-Copper composite membrane through a novel two simultaneous phase separation processes with anti-biofouling property

The preparation of an anti-biofouling membrane is the main focus of this study. This is achieved by incorporating copper (Cu) known for its’ antibacterial property in a polythiourea (PTU) membrane through a novel and facile simultaneous non-solvent induced phase separation (NIPS) and complexation induced phase separation (CIPS) process. This is possible due to the characteristics of PTU to instantaneously form a macromolecular-metal complex with Cu resulting in crosslinking of PTU with subsequent precipitation. The process strategically incorporates Cu in the membrane specifically at the PTU-non-solvent interface which ultimately forms the surface and pore walls of the membrane. The polymerization process of 4,4-oxydianiline and p-phenylene diisothiocyanate for the synthesis of PTU was optimized in terms of molecular weight and processibility for membrane fabrication by phase separation. Characterization of the PTU using Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and static light scattering for molecular weight (MW) determination confirm the polymerization reaction and the suitability of the polymer for the phase separation process and membrane application with MW of PTU around 451±17.59 kilodalton. Similarly, FTIR spectra of PTU-Cu membrane confirm the complexation reaction with the observed decline in the intensity of various functional groups responsible for complexation with an increase in Cu concentration. The PTU-Cu membrane is relatively smoother and more hydrophilic compared to the pristine PTU membrane which indicates its antifouling potential. After filtering 5 grams/liter of a model foulant sodium alginate at 5 bars for 300 minutes, the flux ranges from 76% to 90% of the original flux for the PTU-Cu membrane while about 55% of the original flux for the PTU membrane. Both the surface of the PTU and PTU-Cu membrane showed antibacterial activity against E. coli