Department of Industrial Engineering, National Institute of Technology, Ibaraki College, 866 Nakane, Hitachinaka City, Ibaraki, 312-8508, Japan.
Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima, 960-1296, Japan.
Environ Sci Pollut Res Int. 2020 Jun;27(16):20149-20159. doi: 10.1007/s11356-020-08512-x. Epub 2020 Apr 1.
Waste foundry sand (WFS) from the brass and bronze casting and molding process include various potentially toxic elements (PTEs), such as copper, zinc, tin, and lead. Hence, the utilization of WFS in construction and geotechnical applications evokes environmental concerns due to the rain-induced leaching of PTEs into the groundwater system. The present study investigated the extractive decontamination of WFS using mineral acids, e.g., HCl, HSO, or HNO. Favorable extraction efficiency was achieved with HCl as compared to the other mineral acids, which was further enhanced at high temperatures and increased acid concentrations. The thermodynamic analysis indicated that ≥ 4 mol L of HCl and ≤ 100 °C temperature ensured maximum extraction of PTEs due to the endothermic interactions between the HCl and PTEs. The HCl-treated WFS needed to be rinsed with water to restrict the after treatment elution of PTEs. The hazardous environmental impact of acid-treated WFS was evaluated following the standard leaching test and comparison with legislative recommendations for PTEs, which showed the water-assisted leaching rate of all the PTEs are within the regulatory limits.
废铸造砂（WFS）来自黄铜和青铜的铸造和成型过程，其中包含各种潜在的有毒元素（PTEs），例如铜、锌、锡和铅。因此，由于 PTEs 在雨水的作用下淋滤到地下水系统中，WFS 在建筑和岩土工程中的应用引起了环境方面的关注。本研究使用矿物酸（例如 HCl、HSO 或 HNO）对 WFS 进行了萃取净化。与其他矿物酸相比，HCl 具有更好的萃取效率，并且在高温和高酸浓度下进一步增强。热力学分析表明，由于 HCl 和 PTEs 之间的吸热相互作用，HCl 的浓度至少为 4 mol/L 且温度不超过 100°C 时，能够确保 PTEs 的最大萃取。需要用清水冲洗经 HCl 处理的 WFS，以限制 PTEs 的后续处理浸出。对经酸处理的 WFS 的危害性环境影响进行了评估，方法是根据标准浸出试验和对 PTEs 的立法建议进行比较，结果表明所有 PTEs 的水辅助浸出率均在监管限制范围内。
