Application of waste foundry dust as microwave susceptor in microwave treatment of mercury contaminated soil

Abstract

The present study investigates the use of waste foundry dust (WFD) as an effective microwave susceptor for the remediation of mercury (Hg)-contaminated soils. Two types of soils, carbonate-based and silicate-based were treated using conventional thermal desorption and microwave-assisted heating. The removal efficiency of Hg was evaluated in relation to soil composition, organic content, and heating method. Traditional thermal treatment achieved 99 % Hg removal in carbonate-rich soils at 500 °C, whereas only 86.7 % removal was observed in silicate-based soils under the same conditions. Microwave heating alone was insufficient to reach effective desorption temperatures, but the incorporation of WFD significantly enhanced heating efficiency by generating localized hotspots, resulting in > 90 % Hg removal within 4 min. WFD demonstrated high thermal durability (up to 900 °C), reusability across multiple cycles, and superior microwave absorption due to its iron oxide content. While some degradation occurred after repeated use, WFD still provided sustainable and cost-effective remediation performance. The study highlights the critical role of soil composition in Hg desorption behavior and demonstrates WFD’s potential as a low-cost, high-efficiency susceptor. These findings suggest that WFD-assisted microwave heating is a promising technique for rapid, energy-efficient, and environmentally responsible treatment of Hg-contaminated soils.