Knowledge about heavy metal release from industrial solid wastes (ISWs) is crucial for better management of their environmental risks. This study was conducted to investigate the effect of organic and inorganic acids, clay minerals, and nanoparticles (NPs) on the release of heavy metals from sugar factory waste, ceramic factory waste, leather factory waste, and stone cutting waste. The influence of the extractants on heavy metal release from these ISWs was in the following descending order: citric acid > oxalic acid > nitric acid ≥ sulfuric acid > CaCl2. Addition of clay minerals and NPs as adsorbents decreased heavy metal release, which was significantly lower in NP-treated wastes than in the clay mineral-treated wastes. On the other hand, the presence of organic and inorganic acids increased heavy metal adsorption by NPs and clay minerals. These results suggest that NPs can be applied successfully in waste remediation, and organic and inorganic acids play an important role in the removal of heavy metals from the studied adsorbents.
