Fabrication and characterization of nanocomposite membrane of polyethersulfone (PES) embedded with hyperbranched polyethyleneimine (HPEI) and bismuth vanadate (BiVO4) nanoparticles for the photocatalytic degradation of triclosan in solution

Abstract : An increase in the production and usage of pharmaceutical and personal care products in various water bodies has attracted significant attention amongst the public and scientists. Classified as emerging pollutants, these pharmaceutical and personal care products ultimately accumulate and contaminate several water bodies through several pathways. Although reported to be found at very low concentrations, exposure to these emerging organic pollutants has adverse health effects to humans. Conventional methods are reported to partially degrade emerging pollutants. Therefore, it is of importance to explore effective and innovative methods for the complete degradation of these pollutants. In this study, a photocatalytic-membrane consisting of bismuth vanadate (BiVO4) nanoparticles, hyperbranched polyethyleneimine (HPEI) and polyethersulfone (PES) were used in the degradation of triclosan. BiVO4 is an n-type semiconductor with excellent properties such as lower band gap and visible light active. However, it has drawbacks such as agglomeration and having lower surface area. HPEI was used as a dispersing agent for the BiVO4 photocatalyst as this polymer has been found to be an excellent template/host for the production of monodispersed and uniform size particles. HPEI can also induce hydrophilic properties on the membrane thus alleviating fouling. BiVO4 was characterised using X-ray Diffraction (XRD) and Raman depicted that spectroscopy. These analyses revealed that there was successful synthesis of the monoclinic phase of BiVO4, as well as a phase transformation between the monoclinic phase and the tetragonal phase upon addition of HPEI within the nanoparticles. The modified membranes showed improved water flux and hydrophilicity (71°- 56°) as compared to the bare PES (75°) upon addition of HPEI and BiVO4. The modified membranes were effective in the photodegradation of triclosan (upto 86%) and this was accompanied by the generation of Cl- ions.M.Sc. (Nanoscience