Thermodynamic Study of the Acid-Induced Decontamination of Waste Green Sand Generated in a Brass Foundry
Thermodynamic Study of the Acid-Induced Decontamination of Waste Green Sand Generated in a Brass Foundry
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黄铜铸造厂产生的废绿砂的酸诱导净化热力学研究
DOI：
10.1007/s11356-020-08512-x
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发表时间：
2020
影响因子：
5.8
通讯作者：
Hiroshi Hasegawa
中科院分区：
文献类型：
--
作者：
Hikaru Sawai ; Ismail M.M. Rahman ; Naoyuki Jii ; Yuji Egawa ; Satoshi Mizutani ; Hiroshi Hasegawa
黄铜和青铜铸造成型过程中产生的铸造废砂(WFS)中含有多种潜在的有毒元素，如铜、锌、锡和铅。因此，WFS在建筑和岩土工程中的应用引起了人们对环境问题的关注，因为雨水会导致PTE渗入地下水系统。本研究调查了使用无机酸，例如，HCl、H2SO4或HNO3对WFS进行萃取式去污。与其他无机酸相比，盐酸具有较好的萃取效率，在高温和增加酸浓度的情况下，萃取效率进一步提高。热力学分析表明，由于盐酸与PTE之间的吸热作用，≥ 4、L−1和≤ 100℃的温度保证了PTE的最大萃取率。经盐酸处理的WFS需要用水冲洗，以限制PTE的后处理洗脱。通过标准浸出试验，并与PTEs的立法建议进行比较，对酸处理后的WFS的有害环境影响进行了评价，结果表明，所有PTEs的水助浸出率都在规定的范围内。
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, H2SO4, or HNO3. 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−1of 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.