Solid Brønsted acidity boosts adsorption reactivity of nano-adsorbent for water decontamination

IF 6.1 2区环境科学与生态学 Q2 ENGINEERING, ENVIRONMENTAL

Frontiers of Environmental Science & Engineering Pub Date : 2024-04-02 DOI:10.1007/s11783-024-1841-2

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Abstract

Despite the development of various Lewis acidic nano-adsorbents for fluoride removal through inner-sphere coordination, strong competition for hydroxyl ions still hinders efficient water defluoridation. In addition, the critical issue of polysilicate scaling that results from the ubiquitous silicates must be addressed. To tackle these issues, an alternative approach to enhancing adsorption reactivity by modifying nano-adsorbents with dual Lewis and Brønsted acidity is proposed. The feasibility of this approach is demonstrated by growing zirconium phosphate (ZrP) inside a gel-type anion exchanger, N201, to produce nanocomposite ZrP@N201, in which the confined ZrP contained an otherwise metastable amorphous phase with Lewis acidic Zr⁴⁺ sites and Brønsted acidic monohydrogen phosphate groups (–O₃POH). Compared with the Lewis acidic nano-zirconium oxide analog (HZO@N201), ZrP@N201 exhibited a greatly improved adsorption capacity (117.9 vs. 52.3 mg/g-Zr) and mass transfer rate (3.56 × 10⁻⁶vs. 4.55 × 10⁻⁷ cm/s), while bulk ZrP produced a thermodynamically stable α-phase with Brønsted acidity that exhibited negligible adsorption capability toward fluoride. The enhanced defluoridation activity of ZrP@N201 is attributed to Brønsted acidity and the increased outer electron density of Zr⁴⁺ sites, as corroborated using XPS and solid-state NMR analysis. Moreover, Brønsted acidity strengthens the resistance of ZrP@N201 to silicate, allowing its full regeneration during cyclic defluoridation. Column tests demonstrated 3–10 times the amount of clean water from (waste) for ZrP@N201 as compared to both HZO@N201 and the widely used activated aluminum oxide. This study highlights the potential of developing nano-adsorbents with dual acidities for various environmental remediation applications. Abstract Image

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固体布氏酸性提高了纳米吸附剂的吸附反应活性，从而实现水质净化

摘要尽管开发出了各种通过内球配位去除氟化物的路易斯酸性纳米吸附剂，但对羟基离子的强烈竞争仍然阻碍着水的高效除氟。此外，还必须解决无处不在的硅酸盐导致的多硅酸盐结垢这一关键问题。为了解决这些问题，我们提出了一种替代方法，即通过改性具有路易斯和布氏双重酸性的纳米吸附剂来提高吸附反应性。通过在凝胶型阴离子交换剂 N201 中生长磷酸锆（ZrP），制备出纳米复合 ZrP@N201，证明了这种方法的可行性；在这种纳米复合 ZrP@N201 中，密闭的 ZrP 含有一个原本不稳定的无定形相，该无定形相具有路易斯酸性 Zr4+ 位点和布氏酸性磷酸单氢基（-O3POH）。与路易斯酸性纳米氧化锆类似物（HZO@N201）相比，ZrP@N201 的吸附容量（117.9 对 52.3 mg/g-Zr）和传质速率（3.56 × 10-6 对 4.55 × 10-7 cm/s）大大提高，而块状 ZrP 产生了热力学稳定的α相，具有布氏酸性，对氟的吸附能力微乎其微。利用 XPS 和固态 NMR 分析证实，ZrP@N201 脱氟活性的增强归因于布氏酸性和 Zr4+ 位点外层电子密度的增加。此外，布氏酸性还增强了 ZrP@N201 对硅酸盐的抵抗力，使其在循环脱氟时能够完全再生。柱测试表明，与 HZO@N201 和广泛使用的活性氧化铝相比，ZrP@N201 从（废水）中获得的净水量是后者的 3-10 倍。这项研究强调了开发具有双重酸性的纳米吸附剂在各种环境修复应用中的潜力。

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来源期刊

Frontiers of Environmental Science & Engineering ENGINEERING, ENVIRONMENTAL-ENVIRONMENTAL SCIENCES

CiteScore

10.90

自引率

12.50%

发文量

988

审稿时长

6.1 months

期刊介绍： Frontiers of Environmental Science & Engineering (FESE) is an international journal for researchers interested in a wide range of environmental disciplines. The journal''s aim is to advance and disseminate knowledge in all main branches of environmental science & engineering. The journal emphasizes papers in developing fields, as well as papers showing the interaction between environmental disciplines and other disciplines. FESE is a bi-monthly journal. Its peer-reviewed contents consist of a broad blend of reviews, research papers, policy analyses, short communications, and opinions. Nonscheduled “special issue” and "hot topic", including a review article followed by a couple of related research articles, are organized to publish novel contributions and breaking results on all aspects of environmental field.