Effect of blending polypyrrole coated multiwalled carbon nanotube on desalination performance and antifouling property of thin film nanocomposite nanofiltration membranes

Two nanocomposites were chemically synthesized by depositing hydrophilic polypyrrole on raw or oxidized multiwalled carbon nanotubes (PPy-raw or PPy-oxidized MWCNTs) and applied on fabrication of thin film nanocomposite (TFN) nanofiltration membrane with different concentrations of the nanocomposites. In situ oxidative polymerization of pyrrole was applied, which surfactant dopant and initiator of this reaction were p-toluene sulfonic acid and ammonium peroxydisulfate, respectively. Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) image were used to characterize the synthesized nanocomposites. Contact angle measurement was carried out to study the hydrophilicity of the membranes. The rejection properties of the membranes were measured by Na₂SO₄ solution, which was mixed with bovine serum albumin (BSA) to provide a real environment to study the antifouling properties. The PPy-oxidized MWCNTs membranes revealed surprisingly high fluxes where the PPy-raw MWCNTs membranes improved the permeation as well. The SEM images indicated that PPy-raw MWCNTs membranes had a smooth surface and consequently, PPy-raw MWCNTs membranes showed improvement in antifouling properties, which is evidence that the membrane's surface roughness affects the fouling resistance. Although these membranes showed slightly lower rejection than non-PPy used membranes, their ability to reject the salt was satisfying.