(458c) Phosphorene- Based Antifouling Membranes: Synthesis, Fabrication and Applications

Nanofiltration membranes (NF) have been largely developed and commercialized over the past decade because they show promise for the separation of neutral and charged solutes in aqueous solutions, offer low operation pressure and high flux. However, during nanofiltration, rejected materials can often accumulate on the membrane surface and/or within membrane pores to form a fouling layer. Phosphorene is a single-layer, two-dimensional (2D), exfoliated form of black phosphorus (BP). Phosphorene exhibits interesting and useful features, including its anisotropic electric conductance and optical responses which distinguishes it from other isotropic 2D materials such as graphene, molybdenum, tungsten chalcogenides. Phosphorene exhibits high absorbance, being a direct and narrow band gap semiconductor, and could effectively harvest low energy photons during photocatalysis. The band gap of phosphorene can be tuned sufficiently for photon absorption in the ultraviolet, visible light and the near-infrared region of the solar spectrum. Specifically, relevant to the field of membrane science, the band gap of phosphorene provides it with potential photocatalytic properties, which could be explored in making reactive membranes that can self-clean. Furthermore, phosphorene’s ambi-polar transport characteristics (where both positively and negatively charged carriers conduct current under certain voltage bias conditions provides it with anti-microbial capabilities since applying electrical potential on conductive surfaces can hinder the development of biofilm. The overarching goals of this project are to first prove that phosphorene’s electrical conductivity is anti-microbial, and it also possesses photocatalytic properties to destroy organic compounds; then, to develop novel nanocomposite membranes holistically from the initial investigation of phosphorene to testing. To this end, for the first time, membranes have been embedded with phosphorene. Membrane modification was verified by the presence of phosphorus on membranes, along with changes in surface charge, average pore size, and hydrophobicity. After modification, phosphorene-modified membranes were used to filter methylene blue (MB) under intermittent ultraviolet light irradiation. Phosphorene-modified and unmodified membranes displayed similar rejection of MB; however, after reverse-flow filtration was performed to mimic pure water cleaning, the average recovered flux of phosphorene-modified membranes was four times higher than that of unmodified membranes. Furthermore, coverage of MB on phosphorene membranes after reverse-flow filtration was four times lower than that of unmodified membranes, which supports the hypothesis that phosphorene membranes operated under intermittent ultraviolet irradiation can become self-cleaning. The antimicrobial potential of phosphorene will be tested using Serratia marcescens. The conductivity of phosphorene will be characterized to determine its antibacterial properties. This study will investigate the specific role of electric current in bacterial detachment and inactivation when a constant current is applied through phosphorene. The use of phosphorene to prevent biofilm formation has not been shown and will be examined in this study.