Tahmasi Sima, Samadi Mohammad Taghi, Mansoorian Hossein Jafari, Nasab Hassan Zolghadr, Chavoshi Sonia, Chavoshi Ebrahim, Roshani Maryam, Khazaei Mohammad
Department of Environmental Health Engineering, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran.
Research Center for Health Sciences, Hamadan University of Medical Sciences, Hamadan, Iran.
J Environ Health Sci Eng. 2025 Jun 18;23(2):20. doi: 10.1007/s40201-025-00945-1. eCollection 2025 Dec.
This study investigates the effectiveness of sodium-bentonite geosynthetic clay liners (Na-GCLs) in controlling low-pH leachate from metal industries, simulating conditions in tailings impoundments at zinc and copper mines.
An experimental setup comprising five chambers was used to test Na-GCL performance under 100 kPa pressure with synthetic leachate at four pH levels (1, 3, 5, and 7) and deionized water as a control. The Na-bentonite was characterized using FE-SEM, FTIR, EDX, XRD, swelling index (SI), and pHpzc tests. Hydraulic conductivity (k) was modeled using the Katsumi approach. Leachate samples were collected every 14 days over a 4-month period and analyzed for heavy metal concentrations using ICP-OES.
The swelling index of Na-GCL dramatically decreased from 16 to 2 mL/2 g when exposed to low-pH leachate, significantly impacting its performance. The point of zero charge (pHpzc) was determined to be 4.1. Adsorption capacity for heavy metals (Cu, Mn, Fe, Ni, Zn, and Pb) increased with higher pH values. The Katsumi model parameters for the relationship between hydraulic conductivity (k) and swelling index (SI) were a = -0.3, b = 8.69 mL/2 g-Solid, and R² = 0.875. FTIR analysis revealed subtle changes in OH vibrational peaks between pre- and post-leachate exposure bentonite.
Na-GCL performance is significantly affected by pH conditions, with decreased effectiveness in highly acidic environments typical of mining and metal industry waste. This highlights the need for careful consideration of leachate pH when selecting and implementing GCLs in landfill applications.
本研究调查钠基膨润土土工合成黏土衬垫（Na-GCLs）在控制金属工业低pH值渗滤液方面的有效性，模拟锌矿和铜矿尾矿库的条件。
使用一个由五个腔室组成的实验装置，在100 kPa压力下，用四种pH值水平（1、3、5和7）的合成渗滤液以及去离子水作为对照来测试Na-GCL的性能。使用场发射扫描电子显微镜（FE-SEM）、傅里叶变换红外光谱仪（FTIR）、能量散射X射线光谱仪（EDX）、X射线衍射仪（XRD）、膨胀指数（SI）和零电荷点pH值（pHpzc）测试对钠基膨润土进行表征。采用胜见方法对水力传导率（k）进行建模。在4个月的时间里，每14天采集一次渗滤液样本，并使用电感耦合等离子体发射光谱仪（ICP-OES）分析重金属浓度。
当暴露于低pH值渗滤液时，Na-GCL的膨胀指数从16急剧降至2 mL/2 g，对其性能产生了显著影响。确定零电荷点（pHpzc）为4.1。重金属（铜、锰、铁、镍、锌和铅）的吸附容量随着pH值升高而增加。水力传导率（k）与膨胀指数（SI）之间关系的胜见模型参数为a = -0.3，b = 8.69 mL/2 g-固体，R² = 0.875。傅里叶变换红外光谱分析显示，渗滤液暴露前后膨润土的OH振动峰有细微变化。
Na-GCL的性能受pH条件显著影响，在采矿和金属工业废弃物典型的高酸性环境中有效性降低。这突出了在填埋应用中选择和使用GCL时仔细考虑渗滤液pH值的必要性。
