Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China.
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China.
Water Res. 2024 Jan 1;248:120860. doi: 10.1016/j.watres.2023.120860. Epub 2023 Nov 13.
Specifically designing the heterogeneous interface in sulfidated zero-valent iron (S-ZVI) has been an effective, yet usually overlooked method to improve the decontamination ability. However, the mechanism behind FeS assembly remains elusive and the lack of modulating strategies that can essentially tune the applicability of S-ZVI further imposes difficulties in creating better-performing S-ZVI with heterogeneous interface. In this study, by introducing powdered activated carbon (PAC) during S-ZVI preparation, S-ZVI/PAC microparticles were prepared to modulate the assembly pattern of FeS for the applicability and reactivity of the material. S-ZVI/PAC showed robust performance in Cr(VI) sequestration, with 11.16 and 1.78 fold increase in Cr(VI) reactivity compared to ZVI and S-ZVI, respectively. This was attributed to the fact that the introduced PAC could acquire FeS to enhance the electron transfer capacity matching its adsorption threshold, thus helping to accommodate the transfer of the reduction center to PAC in S-ZVI/PAC. In optimizing the FeS allocation between ZVI and PAC, the chemical assembly of FeS on S-ZVI was superior to physical adsorption. Critically, we found that isolated FeS in the prepared solution was physically adsorbed by the PAC, allowing chemically assembled FeS on the S-ZVI. This was achieved by controlling the addition sequence of NaS and PAC, as it effectively controlled the release rate and content of Fe(II) in the preparation solution. S-ZVI/PAC was demonstrated to be extremely effective in simulated wastewater and electrokinetics-permeable reactive barrier (EK-PRB) treatments. Introducing PAC enriches the diversity of sulfidation mechanisms and may realize the universality of the S-ZVI/PAC application scenarios. This study provides a new interface optimization strategy for S-ZVI targeted design towards environmental applications.
具体设计硫化零价铁（S-ZVI）的非均相界面是提高其去污能力的一种有效方法，但通常被忽视。然而，FeS 组装背后的机制仍然难以捉摸，缺乏能够从本质上调节 S-ZVI 适用性的调制策略，这进一步给创造具有非均相界面的性能更好的 S-ZVI 带来了困难。在本研究中，通过在 S-ZVI 制备过程中引入粉末状活性炭（PAC），制备了 S-ZVI/PAC 微球，以调节 FeS 的组装模式，从而提高材料的适用性和反应性。S-ZVI/PAC 在 Cr(VI)固定方面表现出了强大的性能，与 ZVI 和 S-ZVI 相比，Cr(VI)的反应性分别提高了 11.16 和 1.78 倍。这归因于引入的 PAC 可以获取 FeS 来增强电子转移能力，使其达到吸附阈值，从而有助于将还原中心转移到 S-ZVI/PAC 中。在优化 ZVI 和 PAC 之间的 FeS 分配时，FeS 在 S-ZVI 上的化学组装优于物理吸附。至关重要的是，我们发现，在制备溶液中，孤立的 FeS 被 PAC 物理吸附，允许在 S-ZVI 上化学组装 FeS。这是通过控制 NaS 和 PAC 的添加顺序来实现的，因为它可以有效地控制制备溶液中 Fe(II)的释放速率和含量。S-ZVI/PAC 在模拟废水和电动力学可渗透反应屏障（EK-PRB）处理中都非常有效。引入 PAC 丰富了硫化机制的多样性，并可能实现 S-ZVI/PAC 应用场景的通用性。本研究为 S-ZVI 的环境应用提供了一种新的界面优化策略。
