Conversion of Nanomaterial Waste Soot to Recycled Sc₂O₃ Feedstock for the Synthesis of Metallic Nitride Fullerenes

Abstract

Herein, we address a need in the industrial and academic communities to reduce costs and environmental impact associated with the synthesis of select carbonaceous nanomaterials. In this effort, we have developed a method to recover Sc2O3 from carbonaceous “waste soot”, thereby alleviating the problem of waste disposal of fullerene depleted soot and tremendously reducing the costs and environmental impact of our synthetic process. The recovery process is based on the thermal oxidation and removal of carbon from waste soot as gaseous byproducts (e.g., CO2) to yield a recycled, reusable feedstock. The economic impact is measured in the cost savings of solid waste disposal fees and expensive reagents, such as scandium and some rare-earth metal oxides. Our recovery method is scalable and simple in design. Waste soot at different stages of thermal oxidation is characterized by thermogravimetric analysis (TGA) to determine optimal temperature and soak parameters. Corresponding X-ray photoelectron spectroscopy (XPS) analysis of these samples indicates a comparable chemical composition of Sc2O3 for recycled samples to virgin Sc2O3 controls. Recovered Sc2O3 material was used in our electric-arc reactor and resulted in statistically comparable fullerene product distributions.

Release of Metal Impurities from Carbon Nanomaterials Influences Aquatic Toxicity

“…Yields from this process are generally low; a recent study by Stevenson et al , reported that 1000 g of feedstock were required to generate 1 g of final metallofullerene product, with the remaining ∼999 g of feedstock discarded as solid waste (or “waste soot”). On a mass basis, this solid waste fraction may be comprised of ∼50% feedstock metals, some of which are commercially valuable (e.g., rare-earth metals) or toxic in environmental systems (e.g., Cu), and thus recent efforts have focused on recovering and recycling these materials , . This unexplored area of nanotechnology EHS poses significant challenges for public health officials, waste management authorities, and generators of nanomanufacturing wastes.…”

A Distorted Tetrahedral Metal Oxide Cluster inside an Icosahedral Carbon Cage. Synthesis, Isolation, and Structural Characterization of Sc4(μ3-O)2@Ih-C80

“…The low Sc 2 O 3 content minimizes its use, and recycling waste soot is advised. 10 At this point, we can rank the source of oxygen and its inclusion in Sc 4 (µ 3 -O) 2 @I h -C 80 as follows: NO x from copper nitrate > O 2 from air . O from Sc 2 O 3 .…”

“…Optimal conditions for formation of Sc 4 (μ 3 -O) 2 @ I h -C 80 were an air flow of 0.2 Torr/min with graphite rods packed with 80% Cu(NO 3 ) 2 and 20% Sc 2 O 3 , which leads to a 12% yield from the soluble extract. The low Sc 2 O 3 content minimizes its use, and recycling waste soot is advised . At this point, we can rank the source of oxygen and its inclusion in Sc 4 (μ 3 -O) 2 @ I h -C 80 as follows: NO x from copper nitrate > O 2 from air ≫ O from Sc 2 O 3 .…”

CuCl2 for the Isolation of a Broad Array of Endohedral Fullerenes Containing Metallic, Metallic Carbide, Metallic Nitride, and Metallic Oxide Clusters, and Separation of Their Structural Isomers

“…For the synthesis of scandium carbide endohedrals (e.g., Sc 4 C 2 @I h -C 80 ), an atmosphere deficient in air was used. For scandium carbide soot extracts, cored graphite rods were packed with Sc 2 O 3 or recycled , Sc 2 O 3 and Cu and vaporized under an inert atmosphere (e.g., He).…”