Passive treatment systems provide lower cost alternatives for remediation of mine drainage; however, acidic drainage increases treatment difficulty because of higher metal concentrations and proton competition for reactive substrates. A silica fiber functionalized with (3-aminopropyl) triethoxysilane (Si + APTES) and a naturally-occurring, microporous silicate mineral (clinoptilolite of the zeolite family) were evaluated in the laboratory as potential reactive substrates for passive treatment of mild (≥ pH of 3) acid rock drainage. Column permeability experiments with spun, 10-µm median diameter, silica fiber and loosely packed, 3.6-mm median diameter clinoptilolite indicate greater permeability and stability of clinoptilolite under flowing conditions. Batch sorption experiments with silica fiber (Si), Si + APTES, and clinoptilolite in a synthetic Fe(II)–SO4, pH 3.0 solution indicate an Fe specific sorption efficacy of Si + APTES > clinoptilolite > Si at equivalent surface areas. Specific sorption normalized to packing densities indicate greater sorption per volume for clinoptilolite. Sorption results for Si + APTES and clinoptilolite did not produce isotherms described by the Langmuir or Freundlich models, likely because of surface heterogeneity and precipitation reactions. Column sorption experiments under flowing conditions indicate an Fe removal efficacy of clinoptilolite > Si + APTES for permeable packing densities. Si + APTES demonstrated high specific sorption of Fe in batch sorption experiments and has potential use in low-flow, passive treatment of mildly acidic solutions. The balance of minimal surface preparation, greater permeability, structural stability, large surface area, micropore structure, and ion-exchange properties make clinoptilolite a better reactive substrate for passive treatment of mildly acidic solutions in high- or low-flow conditions.

中文翻译：

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APTES 功能化二氧化硅纤维和斜发沸石降低酸性硫酸铁 (II) 溶液中铁浓度的比较：潜在的被动处理基材

被动处理系统为矿山排水修复提供了成本更低的替代方案；然而，酸性排水会增加处理难度，因为更高的金属浓度和质子对反应性底物的竞争。用（3-氨基丙基）三乙氧基硅烷 (Si + APTES) 和一种天然存在的微孔硅酸盐矿物（沸石家族的斜发沸石）功能化的二氧化硅纤维在实验室中被评估为潜在的反应性底物，用于温和（≥ pH 值为3）酸性岩排水。使用纺丝、10 微米中值直径、二氧化硅纤维和松散填充、中值直径为 3.6 毫米斜发沸石的柱渗透率实验表明，斜发沸石在流动条件下具有更高的渗透性和稳定性。使用二氧化硅纤维 (Si)、Si + APTES 进行批量吸附实验，和斜发沸石在合成的 Fe(II)–SO4、pH 3.0 溶液中表明在等效表面积下 Si + APTES > 斜发沸石 > Si 的 Fe 比吸附效率。归一化为填充密度的比吸附表明斜发沸石单位体积的吸附量更大。Si + APTES 和斜发沸石的吸附结果没有产生 Langmuir 或 Freundlich 模型描述的等温线，这可能是因为表面不均匀和沉淀反应。流动条件下的柱吸附实验表明，对于可渗透填充密度，斜发沸石的除铁效果 > Si + APTES。Si + APTES 在批量吸附实验中表现出对 Fe 的高比吸附，并且在弱酸性溶液的低流量、被动处理中具有潜在用途。最小表面处理的平衡，更大的渗透性，