ANC is a key property of FA solid system and is related to the resistance to acid corrosion, which can affect the matrix’s durability that in turn, affects the leaching of heavy metals (Giampaolo et al., 2002). Based on the ANC curve of S2 sample (Fig. S1), the amount of HNO3 needed for other FA samples can be calculated. Furthermore, the end-point pH values of the lea-chate for each sample were controlled within the range of 1–14. The end-point pH leaching experiments were carried out and ana- lyzed in triplicates