ELECTROSPUN NANOFIBERS FOR WATER TREATMENT

Electrospinning is a very promising fifiber-forming technology that can generate continuous ultrafifine fifibers with diameters ranging from the nano- to the microscale (Reneker and Chun, 1996; Li and Xia, 2010). In general, a typical electrospinning process involves the application of an electrostatic force between a polymer solution kept in a syringe and extruded by a pump and a metal collector as the counterelectrode, such as a flflat plate or a rotating drum, kept at a suitable distance. With the application of a suffificiently high electrical fifield, the electrostatic forces overcome the surface tension of the polymer solution, resulting in the ejection of a thin jet from the pendent drop of polymer solution formed at the tip of the spinneret. The charged jet will fifirst undergo a stable stretching, then bending and whipping, and then deposit randomly on the collector in the form of a textile. Electrospinning has been actively exploited as a facile, versatile, and low-cost technique offering unique capabilities for manufacturing nanofifibers from various solutions, melts, emulsions, or suspensions (Subramanian and Seeram, 2013; Wang and Hsiao, 2016). Electrospun nanofifibers can be deposited conveniently to form a nonwoven mat possessing an interconnected porous structure, high surface area, high porosity, and light weight. In addition, electrospun nanofifibrous membranes (ENMs) can be easily functionalized to meet some certain desirable functions, such as by mixing functional additives into the electrospinning solution (Kaur et al., 2014), or attaching an active species for affifinity adsorption (Ma et al., 2006), surface coating (Wang et al., 2006), or interfacial polymerization (IP) (Yoon et al., 2009a), or some other purposeful surface modifification (Kaur et al., 2007; Min et al., 2012). These advantages give electrospun nanofifibers huge potential for dealing with many arising health, environmental, energy, and other challenges. For example, a nonwoven scaffold of electrospun functional polymer nanofifibers can serve as an ideal affifinity scaffold for adsorption applications owing to its high porosity and large specifific surface area (Min et al., 2012). In general, a large surface-to-volume ratio and many adsorption sites in the matrix are essential for adsorption affifinity membranes to remove heavy metal ions or organic dyes from wastewater.

Although our planet possesses abundant water resources due to the vastness of the oceans, the lack of adequate and clean drinking water is one of the most severe problems we face today. Global safe water scarcity is being exacerbated gradually with the growing human population, rapid urbanizationand industrialization, and climate change. It has been reported that about 50% of the world countries will experience water scarcity by 2025, about 1.2 billion people live without clean drinking water, and 2.6 billion have little or no sanitation (Homaeigohar and Elbahri, 2014). Many emerging water problems caused by urban and industrial pollution are undoubtedly recognized to threaten the environment and human life. For example, toxic heavy metal contaminants from industrial efflfluents (such as Hg, Pb, Cu, and Cd in wastewater from plating, ceramics, glass, mining, and battery manufacturing) discharged into the surface waters cause the contamination of the groundwater and will threaten human health severely. Industries could be the main sources of heavy metal contamination of the local water supply. As for organic pollutants, the level of concentration that would cause health hazards can be even lower than that of heavy metals, thus becoming even more pressing water issues (Huang et al., 2014). In response to this progressive water scarcity and pollution, there is a demand for the development of new, better, and more effificacious separation technologies for the removal of harmful contaminants (e.g., particles, oily emulsion, dyes, metal ions) from wastewater to ensure clean drinking water.

Paper link：https://www.sciencedirect.com/book/9780323512701/electrospinning-nanofabrication-and-applications