VALORIZATION OF INDUSTRIAL/AGRICULTURAL WASTES AND LOW-VALUE CARBONACEOUS FEEDSTOCKS INTO HIGH-PERFORMANCE SUBMICRON/NANO-CARBON MATERIALS

Carbon-based nanomaterials, such as graphene, and carbon nanotubes, offer remarkable potential in diverse engineering applications but face limitations due to high costs and complex synthesis. This study explores the valorization of industrial and agricultural wastes, as well as low-value carbonaceous feedstocks, for the cost-effective production of high-performance submicron/nano-carbon (S/N-C) materials. Three distinct precursors were explored: heavy fuel oil ash (HFOA), an industrial by-product from power and desalination plants; jute sticks, an abundant agricultural residue from jute fiber extraction and raw coal, a widely available, low-cost carbon resource. Each material was subjected to pyrolysis (800^oC) followed by high-energy ball milling (15 hours), resulting in substantial particle size reduction. HFOA exhibited the greatest reduction, from 25 μm to an average of 165 nm. Jute-derived carbon, initially fibrous, reached particle size of ⁓280 nm, while coal-derived carbon averaged around 210 nm. These differences reflect variations in structure and carbon content of the precursor and milling efficiency. The resulting S/N-C materials displayed promising structural and surface characteristics suitable for advanced applications. Notably, HFOA-derived S/NC incorporated into coatings provided 92–98% corrosion protection on steel substrates and decreased the chloride diffusion in concrete by 13-66%. Similarly, coatings incorporating jute-derived S/N-C provided 92–95% enhanced corrosion resistance compared to unmodified coatings. Further, the coal-derived S/N-C exhibited potential as an electrochemical sensing material. Overall, waste-derived S/N-C materials offer a sustainable, low-cost route to high-value nanomaterials, supporting circular economy and expanding the accessibility of carbon nanotechnology in construction sector.