柠檬酸协同黄铁矿对煤矸石硅缓释及土壤砷稳定性的影响研究

Cooperative effect of citric acid and pyrite on the slow-release of silicon from coal gangue and the stabilization of arsenic:Implications for soil remediation

煤矸石是煤炭开采和加工过程中产生的固体废弃物,通常由硅酸盐组成。其在提升硅的生物可利用性方面具有显著潜力,因此可作为农业用硅肥的潜在来源。然而,煤矸石硅的缓释性不足与植物的慢吸收速率存在天然矛盾,限制了煤矸石作为硅肥的应用。本研究探讨了柠檬酸和黄铁矿对煤矸石中硅的缓释效果,以及由此制备的复合物(C@PC-10)对土壤中砷的固化与稳定化作用。研究结果显示,C@PC-10能有效减缓煤矸石中硅的释放速率,在30 d的实验周期内,土壤中水溶态砷和有效态砷的去除效率分别达到71.3%和55.9%。此外,酸溶态砷的比例降低,而残渣态砷的比例增加。模拟酸雨实验进一步表明C@PC-10能够抑制土壤中砷的溶出。通过X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FT-IR)分析,本研究证实了球磨过程中黄铁矿的氧化及其向黄钾铁矾和FeOOH的转化。这些发现揭示了氧化黄铁矿对砷的吸附能力显著增强,表明C@PC-10复合物是一种高效的修复材料,能够调控硅酸盐的释放并有效阻碍土壤中砷的迁移。

The application of coal gangue as a soil amendment shows promise in increasing silicon availability,potentially serving as a silicon fertilizer in agriculture.However,the rapid release of silicon from coal gangue compared to the slow absorption by plants hinders its effective use.This study explored the formation of iron-containing secondary minerals on coal gangue surfaces using pyrite and citric acid to stabilize arsenic in contaminated soils and slow down silicon leaching.After co-ball milling,the silicon leaching rates for coal gangue and the composite C@PC-10 were 0.44%and 0.22%at 60 min,and 1.11%and 1.38%at 120 min,respectively.Stabilization tests showed that C@PC-10 achieved removal efficiencies of 71.3%for water-extractable arsenic and 55.9%for NaHCO_(3)-extractable arsenic over 30 d.Acid-soluble arsenic decreased from 32.8%to 24.1%,while residual arsenic increased from 26.5%to 36.9%.Acid rain simulations demonstrated that C@PC-10 limited leachate arsenic concentration to 28.9 mg/L over 120 d,compared to untreated soil with 59.8 mg/L.Analytical techniques like XRD,XPS,and FT-IR confirmed that pyrite oxidation during ball milling led to the formation of jarosite and FeOOH,enhancing arsenic adsorption capacity.Overall,the C@PC-10 composite shows promise as a remediation material for controlled silicate release and arsenic mitigation in soil environments.