Uliana Adam A, Pezoulas Ethan R, Zakaria N Isaac, Johnson Arun S, Smith Alex, Lu Yubing, Shaidu Yusuf, Velasquez Ever O, Jackson Megan N, Blum Monika, Neaton Jeffrey B, Yano Junko, Long Jeffrey R
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States.
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
J Am Chem Soc. 2024 Aug 28;146(34):23831-23841. doi: 10.1021/jacs.4c05728. Epub 2024 Aug 16.
Chromium and arsenic are two of the most problematic water pollutants due to their high toxicity and prevalence in various water streams. While adsorption and ion-exchange processes have been applied for the efficient removal of numerous toxic contaminants, including heavy metals, from water, these technologies display relatively low overall performances and stabilities for the remediation of chromium and arsenic oxyanions. This work presents the use of polyol-functionalized porous aromatic framework (PAF) adsorbent materials that use chelation, ion-exchange, redox activity, and hydrogen-bonding interactions for the highly selective capture of chromium and arsenic from water. The chromium and arsenic binding mechanisms within these materials are probed using an array of characterization techniques, including X-ray absorption and X-ray photoelectron spectroscopies. Adsorption studies reveal that the functionalized porous aromatic frameworks (PAFs) achieve selective, near-instantaneous (reaching equilibrium capacity within 10 s), and high-capacity (2.5 mmol/g) binding performances owing to their targeted chemistries, high porosities, and high functional group loadings. Cycling tests further demonstrate that the top-performing PAF material can be recycled using mild acid and base washes without any measurable performance loss over at least ten adsorption-desorption cycles. Finally, we establish chemical design principles enabling the selective removal of chromium, arsenic, and boron from water. To achieve this, we show that PAFs appended with analogous binding groups exhibit differences in adsorption behavior, revealing the importance of binding group length and chemical identity.
铬和砷是两种最具问题的水污染物，因为它们毒性高且在各种水流中普遍存在。虽然吸附和离子交换过程已被用于从水中有效去除包括重金属在内的众多有毒污染物，但这些技术在修复铬和砷含氧阴离子方面的整体性能和稳定性相对较低。这项工作展示了使用多元醇功能化的多孔芳香框架（PAF）吸附材料，该材料利用螯合、离子交换、氧化还原活性和氢键相互作用从水中高度选择性地捕获铬和砷。使用一系列表征技术，包括X射线吸收和X射线光电子能谱，探究了这些材料中铬和砷的结合机制。吸附研究表明，功能化的多孔芳香框架（PAF）由于其靶向化学性质、高孔隙率和高官能团负载量，实现了选择性、近乎瞬时（在10秒内达到平衡容量）和高容量（2.5 mmol/g）的结合性能。循环测试进一步表明，性能最佳的PAF材料可以使用温和的酸和碱洗涤进行回收，在至少十个吸附 - 解吸循环中没有任何可测量的性能损失。最后，我们确立了能够从水中选择性去除铬、砷和硼的化学设计原则。为了实现这一点，我们表明附加类似结合基团的PAF在吸附行为上表现出差异，揭示了结合基团长度和化学特性的重要性。
