Specific anion effects on the stability of zeolitic imidazolate framework-8 in aqueous solution

Wang, Huan; Jian, Meipeng; Qi, Zenglu; Li, Yongfeng; Liu, Ruiping; Qu, Jiuhui; Zhang, Xiwang

doi:10.1016/j.micromeso.2017.10.011

Cited by 54 publications

(33 citation statements)

References 30 publications

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“…Phosphate and carbonate in these buffers will likely form insoluble salts when they come in contact with zinc in the composites and cause structural collapse of the composites. Indeed, flake‐like substances, which may be zinc phosphate and zinc carbonate, have been observed after treating pure ZIF‐8 with Na 2 HPO 4 and NaHCO 3, accompanied by severe reduction in the crystallinity of the MOF as observed by XRD analysis [47] …”

Section: Resultsmentioning

confidence: 99%

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A Systematic Study of the Stability of Enzyme/Zeolitic Imidazolate Framework‐8 Composites in Various Biologically Relevant Solutions

2020

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Metal organic frameworks (MOFs) have been used to encapsulate numerous enzymes. This study has encapsulated two enzymes in zeolitic imidazolate framework-8 (ZIF-8) and examined the structural stability of the enzyme@ZIF-8 composites in solutions of various biologically relevant agents (i. e. amino acids, proteins, organic acids, organic/inorganic buffers, surfactants, polymers, carbohydrates and salts). Many of the agents were found to completely dissolve the composites or severely damage their structural integrity, causing the release of the enzymes from the composites. These agents plausibly exerted their destabilizing effects on the composites by interactions with zinc or by complexation with the enzymes in the enzyme@ZIF-8 composites. Notably, Tris and HEPES buffers were found to be supportive of the composites in the short term. The results show the need to improve the stability of the enzyme@ZIF-8 systems for certain applications and suggest triggered release of the encapsulated biomolecules from the porous matrix.

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Section: Resultsmentioning

confidence: 99%

“…Indeed, flake-like substances, which may be zinc phosphate and zinc carbonate, have been observed after treating pure ZIF-8 with Na 2 HPO 4 and NaHCO 3, accompanied by severe reduction in the crystallinity of the MOF as observed by XRD analysis. [47]…”

Section: Inorganic Buffersmentioning

confidence: 99%

A Systematic Study of the Stability of Enzyme/Zeolitic Imidazolate Framework‐8 Composites in Various Biologically Relevant Solutions

2020

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“…However, numerous recent studies have clearly shown that both ZIF-8 crystallites or membranes degrade in aqueous solutions, 40 as a result of a dissolution of ZIF-8 even at RT. 41,42,43,44 In addition, a lack of colloidal stability of ZIF-8 NPs in solvents or polymers has been observed and may lie in the formation of Zn-imidazolate-Zn bonds between particles during the drying, thus resulting in strong adhesive interparticle forces. 31 The strong agglomeration of ZIF-8 particles and their insufficient affinity toward polymer chains can lead to a poor dispersion of MOFs fillers in the polymer matrix, thereby creating interphase defects (macro or nanovoids).…”

Section:  Introductionmentioning

confidence: 99%

Covalent and Selective Grafting of Polyethylene Glycol Brushes at the Surface of ZIF-8 for the Processing of Membranes for Pervaporation

Benzaqui

Semino

Carn

et al. 2019

ACS Sustainable Chem. Eng.

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The so-called Graftfast reaction in water and at room temperature (RT) was applied to graft polyethylene glycol (PEG) at the surface of the microporous zeolitic imidazolate framework ZIF-8 nanoparticles (NPs) using acrylPEG of different chain lengths (480 Da and 5 kDa). In comparison to non-modified ZIF-8 NPs, both chemical and colloidal stabilities of PEGylated ZIF-8 NPs are significantly enhanced in water. A series of colloidal complex fluids by mixing PEG grafted ZIF-8 (i. e. PEG-g-ZIF-8) NPs with different amounts of polyvinylalcohol (PVA) was prepared and characterized by advanced characterization tools such as dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) thereby showing their long-term colloidal stability. Finally, dense and supported mixed matrix membranes were cast from PEG-g-ZIF-8/PVA solutions and have shown high performance in isopropanol (IPA) dehydration by pervaporation. The permeation flux of the supported MMM (i. e. 0.091 kg/(m 2 h) is eleven times higher than that of the pure PVA membrane and these MMMs present a high separation factor (i. e. 7326). These transport properties are presumably due to the molecular sieving effects induced by ZIF-8 and the good interfacial properties of the membrane. The computational exploration of the ZIF-8/PVA and PEG/PVA interfaces provides a microscopic scale explanation for the enhanced compatibility of PVA with the PEGylated MOF when compared to that for the composite based on the bare ZIF-8 as a filler.

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“…That partial collapse of ZIF‐8 could be because of the anion adsorption on ZIF‐8 surface. Researchers have reported that anions in aqueous solution could result in a remarkable impact on solution stability (Sheng et al, 2017; Wang et al, 2018a). Overall, XRD results in different solution pH range matched with patterns of XRD.…”

Section: Resultsmentioning

confidence: 99%

Application of zeolitic imidazolate framework for hexavalent chromium removal: A feasibility and mechanism study

Sheu

Verpoort

et al. 2021

Water Environment Research

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The mechanisms and effectiveness of using zeolitic imidazolate framework (ZIF‐8) [a sub‐family of metal‐organic framework (MOF)] particles on hexavalent chromium [Cr(VI)] removal were evaluated. The ultrasonic mixing method was applied for the preparation of ZIF‐8, and chemicals used for ZIF‐8 synthesis included ammonium hydroxide, zinc nitrate hexahydrate, and 2‐methylimidazole. ZIF‐8 particle had a clear rhombic dodecahedron morphology shape and a strong peak intensity with high crystallinity. The adsorption capacity (AC) of ZIF‐8 was 30.3 mg of Cr(VI)/g of ZIF‐8 [Cr(VI) = 50 mg/L]. The AC of Cr(VI) raised to 34.3 mg/g under acidic conditions (pH = 5), and the AC dropped to below 13.7 mg/g with a pH range from 7 to 11. It could be because of the competitive effects between CrO42− and hydroxide ions for adsorption locations of ZIF‐8. Cr(VI) removal relied on the amount of Cr(VI) adsorbed on the particles of ZIF‐8, and the mechanisms of Cr(VI) adsorption by ZIF‐8 included chemical/physical processes and the rate‐limiting step was the chemical adsorption. A fraction of sorbed Cr(VI) was reduced to Cr(III), and thus, ZIF‐8 could serve as a reducing agent during Cr(VI) reduction. Cr(VI) was removed effectively from the water phase by ZIF‐8 via adsorption and reduction mechanisms. Practitioner Points ZIF‐8 particles had an adsorption capacity of 30.33 mg of Cr(VI)/g of ZIF‐8. Cr(VI) sorption by ZIF‐8 has chemical (rate‐limiting step) and physical processes. ZIF‐8 can serve as a reducing agent for Cr(VI) reduction. Cr(VI) can be removed by ZIF‐8 via the adsorption and reduction mechanisms.

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Specific anion effects on the stability of zeolitic imidazolate framework-8 in aqueous solution

Cited by 54 publications

References 30 publications

A Systematic Study of the Stability of Enzyme/Zeolitic Imidazolate Framework‐8 Composites in Various Biologically Relevant Solutions

A Systematic Study of the Stability of Enzyme/Zeolitic Imidazolate Framework‐8 Composites in Various Biologically Relevant Solutions

Covalent and Selective Grafting of Polyethylene Glycol Brushes at the Surface of ZIF-8 for the Processing of Membranes for Pervaporation

Application of zeolitic imidazolate framework for hexavalent chromium removal: A feasibility and mechanism study

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