Polymeric coatings and thin films are highly versatile platforms to introduce functionalities into a materials system. Immobilization of functional nanomaterials or nano-structured materials into a polymeric matrix provides a simple approach to multifunctional coatings on a variety of substrates. This presentation will discuss two examples of multifunctional nanocomposite coatings in desalination and water purification applications: electrosorption and solar membrane distillation. In the electrosorption process, an ion exchange membrane or coating is applied to the electrode surface to exclude co-ions from accessing the electrode surface and hence increase the charge efficiency. Our research shows that tailored nano-sorbents can be incorporated into the ion exchange coating to achieve selectivity among counter-ions. Utilizing nano-sorbents including nano-sized ion exchange resin particles, MoS4modified layered double hydroxide, and MOF-graphene hybrid materials, we demonstrate highly selective removal of Ca2+, SO42-, Pb2+and CrO42-in the presence of high concentrations of competing ions. This strategy not only provides target ions preferential access to the carbon electrode surface, but enhances electrochemical reactions via direct charge transfer between the electrode and the adsorbed target contaminants. In another study, we develop highly porous, nanocomposite coatings containing low-cost carbon black nanoparticles for direct solar membrane distillation (MD). The photothermal coating enables solarthermal evaporation of water on the surface of the membrane, and overcomes multiple inherent limitations of the conventional MD process responsible for its low thermal efficiency. It provides a promising method to desalinate and treat water and wastewater at off-grid locations. Our research reveals the importance of coating pore size, polymer hydrophobicity, and spatial distribution of the carbon black nanoparticles to the solar MD performance. Macroporous coatings consisting of hydrophilic, electrospun nanofibers with oxidized carbon black nanoparticles on the fiber surface result in the highest membrane flux due to their superior thermal conductivity and minimal resistance to vapor transport. Two critical challenges in developing multifunctional nanocomposite coatings: dispersion of the nanomaterials in the polymer matrix, and binding of the nanomaterials to the surrounding polymer structure, will be discussed.

Multifunctional nanocomposite coatings for desalination and water purification

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.