Journal Article

PUBDB-2025-04026

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Size Matters: Limitations of ZIF-8 Monolith and Its Ni-, Co- and Cu-Doped Variants for Adsorption of Rhodamine B

Velazquez Garcia, J. (Corresponding author)Extern*XFEL.EU*DESY* ; Frenzke, S.DESY* ; de los Santos Valladares, L. ; Barnes, C. H. W. ; Copeman, C. ; Singh, J. ; Kulkarni, S.DESY* ; Keller, T. F.XFEL.EU*DESY* ; Sanchez Cornejo, H. ; Huanaco, D. ; Anwary, M.Extern* ; Elorche, R.Extern* ; Asprilla Herrera, L. M.Extern*DESY* ; Lukaszczyk, W.Extern*DESY* ; Eroglu, N. ; Eifler, D. ; Techert, S.XFEL.EU*DESY*

2025
Royal Society of Chemistry Cambridge

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Please use a persistent id in citations: doi:10.1039/D5MA00797F  doi:10.3204/PUBDB-2025-04026

Abstract: Despite numerous publications reporting the instability of ZIF-8 in water, it is still used for water purification, including the adsorption of molecules significantly larger than the pore window. This work involves the synthesis, characterisation and application of ZIF-8 monoliths, including those doped with Ni, Co and Cu at levels of 4%, 8% and 12%, for rhodamine B adsorption in water. Characterisation techniques include optical microscopy, PXRD, FTIR, SEM-EDX, TGA-FTIR and N2 adsorption. The results reveal mm-cm sized monoliths with identical crystalline structure and morphology, but different properties depending on the doping metal and level. Except for 4% of Co-doped ZIF-8, doping generally narrows the pore size distribution to micropores (maximum between 10.9–11.6 Å), whereas the undoped monolith shows a combination of micropores and mesopores (10.2–38 Å). Doping with more than 4% Co2+ or Cu2+ results in higher BET surface areas (up to 1180 and 1100 m2·g-1, respectively) compared to the undoped monolith (960 m2·g-1). However, when immersed in a 10 mg·L-1 rhodamine B solution, all monoliths exhibit both slower adsorption kinetecs and reduced capacities (0.61 and 1.82 mg·g-1) than reported nano-/microsize particles. Desorption of rhodamine B occurred between 9 and 24 hrs, attributed to up to 20% degradation of the monolith. Immersion in Milli-Q water for five days led to a white residue on the surface, with FTIR indicating a new phase. These results suggest ZIF-8 and its variants are unsuitable for adsorbing large molecules in water but are suitable for small molecules like gases.

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Contributing Institute(s):

1. Strukturdynamik Chemischer Systeme (FS-SCS)
2. Nanolab (FS-NL)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. SFB 1633 C06 - Sub-molekulare Kontrolle über photoinduzierten PCET und PCEnT (C06#) (564189651) (564189651)

Experiment(s):

1. No specific instrument
2. DESY NanoLab: Microscopy

Appears in the scientific report 2025

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Database coverage:
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