Combined extraction and functionalization of low-cost nanoparticles from municipal solid waste fly ash through PICVD

• Process to extract and functionalize nanoparticles from solid waste fly ash.
• Low-cost, value-added nanoparticles are extracted and ready for use.
• Treated particles characterized through SEM, TEM and DRIFTS.

While nanoparticles have been the focus of intensive research for several years as a result of their remarkable surface-driven properties, they remain, for the most part, stuck in the lab. This unfortunate fact can be explained by three main reasons: (1) most studies have not dealt with the scalability and cost issues related to the use of nanomaterials on an industrial scale; (2) a great deal of focus has been applied to “outlier” results that promise far more than can be delivered; and (3) very little attention has been given to surface engineering. We propose to curtail the significant cost issue by extracting low-cost, low-grade nanoparticles that are appropriate for several applications from a ubiquitous and abundant feed stock: fly ash from municipal solid waste (MSW) incineration. The novel technique we apply is capable of both extraction and functionalization of the nanoparticles present in this undervalued waste stream using photo-initiated chemical vapor deposition (PICVD). By setting functionalization conditions to favor hydrophilic surface properties, the treated ash can readily be dispersed in a polar solvent such as water: larger particulates then settle out of suspension, while the lighter nanoparticles remain in the supernatant and are ready for use. While it is true that this method yields low-grade nanoparticles (polydisperse and multi-composite), these can be used in a variety of applications where composition is less crucial, such as increasing the thermal conductivity of composites and nanofluids.