Low-carbon and low-toxicity cement-based solidification/stabilization of MSW incineration fly ash by carbon nanodots

Cement-based solidification/stabilization (S/S) is the most common method for treating heavy metals in municipal solid waste incineration fly ash (IFA). However, the high cement demand in conventional S/S processes results in considerable carbon emissions, compromising the environmental sustainability of this approach. To address this issue, this study first employs low-cost carbon nanodots (CNDs) with dual synergistic functionalities to significantly enhance the cement-based S/S of heavy metals in IFA. The addition of 0.4 wt% CNDs reduces the leaching of Pb, Cd, and Zn by 43.97%, 89.20%, and 37.99%, respectively. Adsorption experiment and phase composition analyses indicate that the enhanced immobilization arises from the synergistic effects of promoted hydration and the interaction between the O/N-containing surface functional groups and heavy metal ions. Furthermore, incorporating 0.4 wt% CNDs reduces both carbon emissions and the overall pollution toxicity index by 46.79% and 38.54%, respectively, highlighting the environmental benefits of this strategy. This study not only offers a cost-effective nanomaterial to enhance the S/S of heavy metals in IFA, but also explores the engineering potential of CNDs.